WO2001027475A1

WO2001027475A1 - Multi-stage diaphragm-type compressor

Info

Publication number: WO2001027475A1
Application number: PCT/DE2000/003631
Authority: WO
Inventors: Christie St Clair Cunningham
Original assignee: Winter, Hermann-Josef
Priority date: 1999-10-11
Filing date: 2000-10-10
Publication date: 2001-04-19
Also published as: DE50012614D1; DE10083104D2; EP1220991B1; ATE323832T1; EP1220991A1; AU1993801A

Abstract

The invention relates to a multi-stage diaphragm-type compressor (100) and to a method for the multi-stage compression of gases. At least two piston-cylinder units arranged at equal angular intervals from each other around the axis of rotation of a camshaft or eccentric shaft (18). The cylinders (7) are connected to a sump (14) containing a liquid, so that they can be filled with a liquid via supply lines (24, 25, 26, 27) in which return valves (28) are provided. The cylinders (7) are also separated from chambers (8) by a membrane (5) to which a gas inlet and a gas outlet (10) with a return valve, respectively are joined. The individual compressor stages are each formed by a piston-cylinder unit with a membrane (5) and a chamber.

Description

Multi-stage membrane compressor

The invention relates to a multi-stage membrane compressor and a method for multi-stage compression of gases with such a membrane compressor.

As is known, membrane compressors for compressing fluids have advantages over conventional piston compressors, in particular with regard to sealing, occurring leakage losses and resulting contamination problems which are typical for piston compressors.

The main disadvantage of the known diaphragm compressors is the wear of the diaphragms, as a result of the constant bending of the elastic diaphragm material (previously steel sheets) due to the acting forces, which act either directly mechanically or hydraulically on the diaphragm. If the membrane for sucking and compressing a fluid is moved indirectly with a hydraulic fluid, problems with reduced delivery capacity, lower compression pressure or damage to the membrane occur in particular as a result of incomplete filling with hydraulic fluid or overfilling.

For many applications and here in particular for the operation of internal combustion engines with gaseous fuels, such as natural gas, it is necessary to compress such a gas relatively high, both for storage and for refueling, final pressures in the range of 250 bar being desired ,

It is therefore an object of the invention to provide a multi-stage membrane compressor for gases. len with which high compression pressures can be achieved with high effectiveness and reliable operation.

According to the invention this object is achieved with a multi-stage membrane compressor according to claim 1. Advantageous embodiments and developments of the invention can be achieved with the features mentioned in the subordinate claims.

The multi-stage diaphragm compressor according to the invention uses a certain number of compressor stages, which are pneumatically connected to one another in series, depending on the compression end pressure required. At least two such compressor stages, each consisting of a piston-cylinder unit, a membrane and a chamber, are used. The piston-cylinder units are arranged at the same angular distances from one another, radially around the axis of rotation of a cam or eccentric shaft with which the respective pistons are moved back and forth in a translatory manner. In addition, supply lines for filling the cylinders with a liquid are connected to the cylinders. The liquid is fed into the cylinders via the feed lines from a sump containing the liquid.

The cylinders in which the liquid is taken up and the chambers into which the gas to be compressed or to be compressed to a higher degree leaves the chamber via a gas inlet and after execution of the compression stroke via a gas outlet are separated in a fluid-tight manner by means of a membrane. Check valves are provided in the supply lines for the liquid and also in the gas inlets and gas outlets. arranges so that fluid leakage losses can only occur between the piston and the cylinder wall and are accordingly low.

In a two-stage diaphragm compressor according to the invention, the two piston-cylinder units with the associated chambers are to be arranged diametrically opposite one another, as is also the case with boxer engines.

However, there is also the possibility of arranging at least three piston-cylinder units with associated chambers at an angular distance of 120 ° or less from one another.

If more than two compressor stages are required in order to achieve a correspondingly high compression end pressure, several piston-cylinder units with the associated chambers, each of which forms a compressor stage, can be in one plane (eg with cylinder longitudinal axes arranged parallel to the horizontal or vertical) Row can be arranged. For example, in the case of a four-stage diaphragm compressor, the individual compressor stages with their piston-cylinder units can also be arranged at angular intervals of 90 °, so that, for example, two piston-cylinder units are diametrically opposed in the horizontal direction and the other two piston-cylinder units are also diametrically opposed in the vertical direction Direction aligned, are arranged.

The liquid that is to be present in the cylinder for the corresponding movement of the respective membrane can be from an existing at the bottom of a housing Sump or an additional tank is sucked in through the supply lines to the individual cylinders when the respective piston moves in the direction of bottom dead center (bottom reversal point) and any leakage losses that occur can be compensated accordingly. When the piston moves in the opposite direction, i.e. in the direction of top dead center (top reversal point), a check valve arranged in the respective feed line prevents the liquid from flowing back. Suitable hydraulic oils, which additionally ensure the lubrication of pistons, cylinders and the drive elements and which do not attack the elastomeric membrane material, are preferably used.

The cylinder bore and the distance covered by the piston between the two dead centers should be designed so that the corresponding stroke volume of two subsequent compressor stages should be assigned in almost the same ratio as the achievable pressure conditions at the end of the compression cycles of the two compressor stages.

To reduce wear, friction and friction losses, it is expedient to attach roller bearings to an eccentric shaft, each of these roller bearings engaging a piston of a compression stage and controlling its translational back and forth movement.

In particular for the movement of the pistons in the direction of bottom dead center (BDC), it is advantageous to apply a compressive force to the respective piston, acting in this direction, which in the simplest case involves a compression spring arranged and fixed in the cylinder can be achieved.

It is also advantageous to use membranes which have a central stiffened area in their center, for example a metal plate connected to the elastomeric part of the membrane. The area of the membrane around the central stiffened area remains elastic and the peripheral outer edge of the membrane should be shaped so that it can be held in the housing of the membrane compressor in a positive and / or non-positive manner.

In particular, if the filling or refilling of the cylinders with liquid solely by suction due to the piston movement in the direction of the lower one

Dead center occurs, it is advantageous to ensure a sufficient liquid volume in the cylinder to form a shoulder on the upper edge of the respective cylinder, which is oriented orthogonally to the direction of movement of the piston and on which the central stiffened area of the membrane rests before reaching the bottom dead center position. Then liquid can be sucked into the cylinder until the bottom dead center is reached through the feed line, the opening of which is arranged in the cylinder below the upper edge of the cylinder. Such a shoulder can, however, also be designed in the form of a cone, in which case the central stiffened region of the membrane should also be designed to be complementary and conical.

For certain arrangements for piston-cylinder units and here those arranged above the axis of rotation of the cam or eccentric shaft, it may be advantageous to fill the cylinder with Use an additional feed pump to carry out the liquid alone or additionally and if possible in a metered form.

In this case, a corresponding feed pump can be arranged in the liquid sump, and a diaphragm or piston pump that is used for this purpose can also be driven via the cam or eccentric shaft, the filling with a certain, respectively identical, liquid volume each time the piston moves towards bottom dead center.

In order to protect the peripheral, elastic region of the membrane and to displace liquid, it is advantageous to chamfer the part of the cylinder which adjoins the shoulder or an edge without a shoulder, which correspondingly applies to the corresponding edge region of the chamber for the gas to be compressed. meets. The flexible edge area of the membrane can rest on these beveled edges in the bottom dead center position and in the top dead center position (TDC). When the corresponding piston moves towards bottom dead center, the flexible edge area of the diaphragm first lies against the bevel and can gradually displace the liquid that is still there back into the cylinder.

For safety reasons, a safety valve can be connected to the cylinder, the opening pressure of which is greater than the maximum working pressure of the liquid to be expected or occurring in the cylinder. It can also be advantageous to also preload the membranes, for example with compression springs arranged and fixed in the cylinders. These springs should preferably engage the central stiffened area of the membranes.

It may also be advantageous to design such pistons, which are moved back and forth translationally in deviation from the horizontal plane, as reciprocating pistons open in the direction of the respective membrane, so that they are cup-shaped and the liquid is contained in the cavity formed. The mass of the pistons can be reduced in this way.

In the case of pistons which are arranged essentially below the axis of rotation of the eccentric or camshaft, a vent hole with a small diameter should be formed in the upward-facing end face, i.e. the end face which presses against the cam, eccentric shaft or a roller bearing attached thereon , through which liquid leakage leaks only slightly, but air in the cylinder can escape.

For example, gas can be compressed in several compression stages with a membrane compressor according to the invention, in which, for example, an eccentric or camshaft is driven with an electric motor, possibly via a gear. As a result of the rotation of this shaft, the pistons of the correspondingly used compressor stages are moved back and forth between the top and bottom dead centers. Corresponding pressure differences can be found in the respective cylinder in which liquid is contained and that which is separated from the cylinder by means of a membrane Chamber be sucked in or compressed according to the direction of movement of the piston gas. Thus, when the piston moves towards bottom dead center, i.e. in the direction of the axis of rotation of the camshaft or eccentric shaft and at the same time the diaphragm bends in this direction, the volume of the chamber is increased and the gas through the gas inlet and a therein or thereon existing check valve is sucked into the chamber. After reversing the direction of movement of the piston, the liquid acts against the membrane by reducing the volume in the cylinder and this is bent in the same direction in which the piston moves, so that the chamber volume is reduced and consequently the gas contained therein is compressed and via the gas outlet , in which a check valve is also arranged, is displaced. From there, it can be pressed through a correspondingly further gas inlet into a chamber of a subsequent compression stage, in which further compression of the gas is achieved, or from the last compressor stage into a gas store.

When the pistons of the individual compressor stages move towards the bottom dead center, liquid can be sucked into the cylinder via a respective feed line, check valves should also be arranged in the feed lines here, which prevent the sucked-in liquid from flowing back.

By appropriate design and arrangement of the outlet opening from the supply lines, the membrane and cylinder, it can be ensured that in the cylinder, in particular during the compression cycle, there is always a sufficient volume of liquid, if possible in excess. hold so that all leakage losses from the previous compression cycle can be compensated. A small excess present in practice can escape via a safety valve when top dead center is reached.

Of course, this effect can also be achieved in other ways with elements such as can be achieved with the feed pump already mentioned.

Pressure sensors should advantageously be present on the gas connection lines, via which the individual compressor stages and a gas storage device can be connected, with which pressure sensors can be used to indicate an error or to switch off the drive for the diaphragm compressor after the maximum or minimum pressure values which can be specified have been exceeded or fallen below are.

Usually, an excess promoted with such an element is only required for the first compression stage. In the other compression stages, leakage losses can be compensated for by sucking in liquid from a sump by means of a negative pressure generated when the piston moves to the bottom dead center.

It would be ideal to match the chamber exactly to the volume of funding. If the chamber is only slightly smaller, a higher hydraulic pressure can occur. To prevent such a risk and to enable acceptable manufacturing tolerances, it can also be advantageous to choose the volume of the chamber of the compressor stages to be at least 2.5%, preferably about 10% larger than the stroke volume of the respective because piston-cylinder unit, which also ensures that the compression stroke can be carried out easily.

To prevent the membrane from closing the gas outlet before the compressed gas has been completely displaced from the chamber during the compression stroke, an elastic element, for example a rubber buffer, can be attached to the inside wall of the chamber on which the gas outlet is arranged protrudes into the chamber, against which the membrane is pressed at the end of the compression stroke.

Compressed gas can advantageously be cooled, with cooling subsequently being able to take place at at least one compressor stage. In this case, a gas guide line between or following at least one compressor stage, through which the correspondingly compressed gas is led, can be air-cooled or water-cooled with the aid of additional heat exchangers.

For the detection of membrane defects, a sensor or detector can be provided in a line for compressed gas, with which it can be recognized whether oil is carried in the compressed gas. Such a sensor can, for example, be a light source with a correspondingly arranged optical detector, with which the light intensity of the light emitted by the light source can be measured. If there is liquid, eg oil, in the compressed gas, the measured value for the light intensity drops and a membrane defect can be diagnosed. Such a sensor is advantageously arranged downstream of the gas outlet of the last compressor stage. net.

The membrane compressor according to the invention is distinguished from conventional compressors by the safe separation of gas and liquid or other contaminating constituents. In particular, because of the favorable lubrication conditions on all moving parts, it requires lower manufacturing tolerances.

It can be easily assembled so that low manufacturing costs can be achieved. Due to the simple construction and assembly, any necessary repairs can also be carried out simply and quickly, the accessibility of the individual elements being achieved by rotating the housing around the shaft after opening the housing or housing parts.

Although the compressed gas is oil-free, the structure and the functional principle used ensure safe and adequate lubrication, in particular also for the pistons moving back and forth, with the increased liquid pressure. For the pistons, the commonly used piston rings can be dispensed with.

The desired volume flows can be achieved simply by varying the drive speed. In addition to the control of an electric motor, a transmission can also be interposed to influence the drive speed, which in the simplest and cheapest case can be a belt transmission. With high required volume flows, it may be necessary to pre-compress the gas to be compressed. before the first compressor stage, for example with a simple radial compressor.

The invention will be explained in more detail below by way of example.

Show:

Figure 1 is a sectional view of an example of a membrane compressor according to the invention;

Figure la one compared to that shown in Figure 1

Example modified membrane compressor in a sectional view;

Figure 2 is a view rotated by 90 °, in a

Sectional view of the example shown in Figure 1;

Figure 2a shows the example shown in Figure la in a view rotated by 90 ° in a sectional view;

Figure 3 shows a feed pump for liquid in three different operating positions;

FIG. 4 shows schematic representations of membranes separating cylinders and chambers in different operating states;

Figure 5 shows an example of a gas inlet valve;

FIG. 6 shows an example of a gas outlet valve;

Figure 7 Examples of edge designs of the membrane for the non-positive and positive fixing of the membrane in a housing;

FIG. 8 shows an example of a pressure-controlled safety valve.

1, 1a, 2 and 2a schematically show examples of a diaphragm compressor 100 according to the invention, each with four compression stages 1 to 4, in different views. With a compression ratio in the individual compression stages of 1: 4 in each case, a final pressure of approximately 256 bar can be achieved, with an outlet pressure which is present at a gas inlet 9 at compression stage 1 of only a few kPa above atmospheric pressure.

In the examples shown in FIGS. 1, 1 a, 2 and 2 a, the piston-cylinder units with membrane 5 and the chambers 8 forming the compression stages are arranged at an angular distance of 90 ° in each case about the axis of rotation of the eccentric shaft 18 used here.

In all figures, the connection lines for the gas, via which the compressed gas is led from compression stage to compression stage, have been omitted. In the views shown in FIGS. 1 and 1 a, only the compression stages 1 and 2 can be seen, which are arranged diametrically opposite one another. Accordingly, it can be ensured that at times at which the piston 13 of the compression stage 1 arranged vertically above is at the bottom dead center, that is to say the intake stroke has been carried out, the piston 13 of the compression stage 2 is at its top Dead center is located, so the compression stroke has been carried out. Analogously, this also applies to the compression stages 3 and 4 which can be seen in FIGS. 2 and 2a.

The eccentric shaft 18 is mounted with roller bearings in the housing 6 of the diaphragm compressor 100, and roller bearings 17 are applied to the eccentrically formed part of the eccentric shaft 18, with each of the roller bearings 17 having a piston 13 of a compression stage 1 to 4 in contact with an end face and at Rotation of the eccentric shaft 18 can be moved back and forth in translation.

To ensure intimate contact of the end face of the respective piston 13 with the surface of its associated roller bearing 17 and here in particular for the return movement to the respective bottom dead center, 7 springs 35 are fixed in the cylinders, which the piston 13 with a corresponding pressure force in the desired direction apply.

Compensation masses 32 are formed on or attached to the eccentric shaft 18 on both sides of the eccentrically designed part in order to avoid unbalance when the eccentric shaft 18 rotates.

At each chamber 8 of a compression stage 1 to 4 there is a gas inlet 9 and a gas outlet 10, in which check valves 33 and 34 are arranged in accordance with the desired flow direction of the gas.

In the lower part of the housing 6 there is a sump 14 which is suitable for the operation of the diaphragm compressor required liquid, for example a hydraulic oil, with a certain oil level 15, from which the liquid can reach the cylinders 7, the individual compression stages 1 to 4 via the feeds 24, 25, 26 and 27. In each of the feeds 24, 25, 26 and 27, a check valve 28 is arranged, with which the backflow of the liquid from the cylinder 7 into the sump 14 can be prevented.

In the examples of diaphragm compressors 100 shown here, the liquid is conveyed from the sump 14 into the cylinders 7 into the compression stages 2, 3 and 4, exclusively by suction during the intake cycles, i.e. when the respective piston 13 moves in the direction of the respective bottom dead center.

In the compression stage 1 arranged vertically at the top of the housing 6 here, the liquid or hydraulic oil is conveyed with the aid of the piston pump 16 arranged at the bottom of the housing 6, in the region of the sump 14, which is also driven by the eccentric shaft 18 via a roller bearing 17 , The piston pump 16 is arranged such that the liquid is conveyed into the cylinder 7 of the compression stage 1 when the piston 21 moves, as shown in the right illustration of FIG. 3, when the piston 13 moves towards its bottom dead center emotional. With a piston pump 16 of this type, a defined volume of liquid can be pumped into the cylinder 7 of the compression stage 1 in each cycle, in particular to compensate for the leakage losses occurring between the piston and cylinder walls and to ensure that the cylinder 7 is always is sufficiently filled with liquid.

After execution of the intake stroke, the compression stroke is carried out for the respective compression stage 1 to 4 by moving the piston 13 in the direction toward its top dead center, the liquid present in the cylinder 7 against the membrane 5 separating the cylinder 7 and the chamber 8 acts and the membrane 5 moves towards the other chamber wall, so that the chamber volume is reduced, the gas contained therein is compressed and displaced via the gas outlet 10 either into the subsequent compression stage or into a gas storage unit connected to the compression stage 4.

In the examples shown here, membranes 5 made of elastomer were used, which have a central stiffened area 101, for example a metal plate. The adjoining outer edge region 5a is as shown in particular in FIG

Figure 4 becomes recognizable, flexible and elastic.

A shoulder 11 is formed on the upper edge of the cylinders 7, against which the central stiffened area 101 of the diaphragm 5 bears when the intake stroke is executed, that is to say the movement of the respective piston 13 toward its bottom dead center, preferably before it is reached. As a result, a negative pressure can be generated in the cylinder 7 closed in this way when the piston 13 moves further to the bottom dead center, and liquid can be sucked into the cylinder 7.

The region of the cylinder edge adjoining the shoulder 11 is bevelled, so that the flexible edge region 5a of the membrane 5 can gently rest against it when the intake stroke is carried out and the liquid still located there is reliably displaced. In order to protect the flexible edge area 5a, the edge of the chamber 8 is also bevelled accordingly.

At the compression stage 1 in particular, an elastic element, here a rubber buffer 31, is arranged on the upper chamber wall, which protrudes at least to the extent into the interior of the chamber 8 that when the compression cycle is carried out, the gas outlet 10 does not precede the complete displacement of the compressed gas from the Chamber is closed by the membrane 5.

An adjustable safety valve 30, which is connected to the cylinder 7, is also shown at the compression stage 1. With such a safety valve 30, excess pressures in the cylinder 7 can be avoided and excess liquid volume can be discharged if the opening pressure of the respective safety valve 30 is slightly (eg 0.5 bar) above the maximum permissible pressure in the cylinder 7 and accordingly also the maximum pressure in the chamber 8 when the compression stroke is carried out. Such safety valves 30 can of course also be present on all four compression stages 1 to 4.

In the examples shown here, the pistons 13 of compression stages 1 and 2 are cup-shaped and hollow. In the case of the piston 13 arranged below the axis of rotation of the eccentric shaft 18, the compression stage 2 is in its upper end face here, which points in the direction of the eccentric shaft 18, a vent hole 13.1 with a diameter of approximately 0.3 mm is formed, with which the escape of air which has entered can be achieved after the membrane compressor 100 has been out of service, but which is due to the small vent hole 13.1 allows only a small loss of fluid leakage.

In the diaphragm 5, which was used for the compression stage 1, a spring 12, with which the diaphragm 5 is prestressed, was dispensed with, since a force effect in the direction of bottom dead center can be achieved solely due to gravity. In the other compression stages, corresponding springs 12 are present on the membranes 5 in order to support this movement.

The example of a diaphragm compressor 100 shown in FIGS. 1 a and 2 a differs from the example shown in FIGS. 1 and 2 essentially by the arrangement of the feed 25 for liquid in the cylinder 7 of the compression stage 2 and the additional representation of the gas inlet and outlet 9 and 10 with check valves 33 and 34 at compression stage 1.

In Figures 2 and 2a, the feed pump 16 is shown in a staggered arrangement in order to emphasize the functional principle. In fact, the piston pump 16 is aligned with the piston 13 of the compression stage 2 below the axis of rotation of the eccentric shaft 18.

The structure of such a piston pump 16 is shown schematically in FIG. 1 at the bottom right and FIG. provides. The piston 21 is guided in the cylinder 20 and is biased with the compression spring 22 against a roller bearing 17, so that the piston can move up and down when the eccentric shaft rotates, as can be seen in the various representations of FIG. 3. In the position shown on the left in FIG. 3, the piston 21 is in its uppermost position and the feed opening 19 is exposed. By turning the eccentric shaft further, the piston 21 is moved downward, the feed opening 19 is closed and the liquid contained in the cylinder 20 through the check valve 23 arranged at the lower part of the cylinder 20 into the feed 24 and from there via the further check valve 28 into the cylinder 7 promoted compression level 1. The feed opening 19 is arranged below the oil level 15.

However, the examples shown in FIGS. 1, 1 a, 2 and 2 a can also be modified such that a four-stage diaphragm compressor 100 is not formed, as shown here, but only a two-stage diaphragm compressor 100. For this purpose, compression stages 1 and 2 or compression stages 3 and 4 can be omitted.

The membranes 5 are made of a suitable flexible material, such as one that is available under the trade name "Viton", and the otherwise flexible membrane 5 is stiffened in its central region 101 with the metal disc already mentioned or in some other form, so that the Membrane 5 is sufficiently stable in this critical area and can withstand the correspondingly acting high forces, in particular at high pressures. In addition, the central stiffened loading secures rich 101 that no further deflection of the membrane can occur when applied to the shoulder 11.

A force is exerted on the membranes 5 by the springs 12, so that when the suction stroke is carried out, the flexible edge area 5a rolls in the direction of the shoulder 11 and that the liquid located between the flexible edge area 5a and the beveled cylinder wall is completely distorted. is pressed before the central stiffened area 101 sits on the shoulder 11 and thus oil losses can be avoided.

FIG. 4 shows various positions of the membrane 5, which correspond to different operating states of a compressor stage. 4a to 4d show a membrane 5 alone, as can be used, for example, in the compressor stage 1, and FIGS. 4e to 4h show a membrane 5 with an additional spring 12.

In FIGS. 4a and 4e, the membrane 5 is located shortly before or at the end of the compression stroke, in which the respective piston 13 is shortly before or at its top dead center.

After reversing the direction of movement of the piston 13 in the direction of its bottom dead center, the pressure in the cylinder 7 decreases and the diaphragm moves in the same direction as in FIGS. 4b to 4d and 4f to 4h. It becomes clear that this movement can be supported and accelerated by means of the spring 12. During this movement of the membrane 5, the flexible edge region 5a rests against the slope of the cylinder wall, possibly displacing it there any liquid still present through the gap between the stiffened area 101 of the membrane 5 and the shoulder 11 until the stiffened central area 101 seals against the shoulder 11. At this point in time, the chamber 8 is completely filled by sucking in gas, and when the piston 13 moves further towards the bottom dead center, the pressure in the cylinder 7 decreases, so that liquid in through the respective feed 24, 25, 26 and 27 the cylinder 7 can be sucked in.

FIG. 5 shows an example of an inlet valve 33 for gas in an exploded and a sectional view.

Figure 6 accordingly shows an outlet valve for gas in an exploded and sectional view.

Examples of the formation of the radially outer edge of the membrane 5, which can be held in the housing 6 in a non-positive and / or positive manner, are shown in FIG. The example shown on the right is particularly preferable.

FIG. 8 shows an example of a pressure-controlled safety valve 30, in which both the pressure in the chamber 8 and in the cylinder 7 of the respective compression stage can be used for control purposes.

Claims

claims

1. Multi-stage diaphragm compressor for gases, so that at least two piston-cylinder units (7, 13) are arranged at the same angular distance from each other around the axis of rotation of a cam or eccentric shaft (18); that the cylinders (7) for filling with a liquid are connected to a sump (14) containing a liquid via feed lines (24, 25, 26, 27) in which check valves (28) are present, that the cylinders ( 7) separated from chambers (8) by means of a membrane (5), to each of the chambers (8) a gas inlet and a gas outlet (9, 10), each with a check valve (33, 34), and a piston-cylinder unit (7, 13) with membrane (5) and chamber (8) form a compressor stage (1, 2, 3, 4).

2. Diaphragm compressor according to claim 1, characterized in that at least two

Piston-cylinder units (7, 13) with associated chambers (8) are arranged diametrically opposite one another.

3. Diaphragm compressor according to claim 1, characterized in that at least three piston-cylinder units (7, 13) with associated chambers (8) are arranged at an angular distance of 120 ° to one another.

4. Diaphragm compressor according to one of claims 1 to 3, characterized in that a plurality of piston-cylinder units (7, 13) with associated chambers (8) are arranged in a plane in a row.

5. Diaphragm compressor according to claim 1, characterized in that four piston-cylinder units (7, 13) with associated chambers (8) are arranged at an angular distance of 90 ° to one another.

6. Diaphragm compressor according to claim 1 or 5, characterized in that a feed pump (16) arranged in the sump (14) is connected to the feed line (24) for the vertical cylinder (7) arranged at the top.

7. Diaphragm compressor according to claim 6, characterized in that the feed pump

(16) is a piston or diaphragm pump driven by the cam or eccentric shaft (18).

8. Diaphragm compressor according to one of claims 1 to 7, characterized in that a roller bearing (17) for driving a piston (13) and / or the feed pump (16) is / are attached to the eccentric shaft (18).

9. Membrane compressor according to one of claims 1 to

8, characterized in that the pistons (13) are pressurized against the cam or eccentric shaft (18).

10. Membrane compressor according to one of claims 1 to

9, characterized in that the membranes (5) have a central stiffened central part (101) and an outer flexible edge region (5a).

11. Membrane compressor according to one of claims 1 to

10, characterized in that the membranes (5) are prestressed with compression springs (12).

12. Diaphragm compressor according to one of claims 1 to 11, characterized in that the upper edge of the cylinder (7) in the form of a shoulder (11) for abutting a part of the central stiffened area (101) before reaching the bottom dead center position of the respective Piston (13) is formed.

13. Diaphragm compressor according to one of claims 1 to 12, characterized in that the to

Shoulder (11) adjoining peripheral edge region of the upper edge of the cylinder (7) and the corresponding edge region of the chamber (8), on which the flexible edge region (5a) of the membrane (5a) is located in the upper and lower dead center position of the piston (13). 5) created, beveled.

14. Diaphragm compressor according to one of claims 1 to 13, characterized in that a safety valve (30), the opening pressure of which is greater than the maximum working pressure occurring in the cylinder (7), is connected to at least one cylinder (7).

15. Diaphragm compressor according to one of claims 1 to

14, characterized in that pistons (13) which move translationally back and forth are formed as reciprocating pistons open in the direction of the respective membrane (5).

16. Diaphragm compressor according to one of claims 1 to

15, characterized in that with the eccentric, camshaft (18) or a roller bearing

(17) in contact with the end face of a piston (13), a ventilation bore (13.1) is formed below the axis of rotation of the eccentric or camshaft (18) piston-cylinder unit (7, 13).

17. Diaphragm compressor according to one of claims 1 to

16, characterized in that the membranes (5) are held on their outer edge in the housing (6) in a positive and / or non-positive manner.

18. Diaphragm compressor according to one of claims 1 to

17, characterized in that the volume of the chambers (8) is in each case at least 2.5% larger than the stroke volume of the corresponding piston

Cylinder unit (7, 13).

19. Diaphragm compressor according to one of claims 1 to

18, characterized in that on the wall of the chamber (8) on which the gas outlet (10) is arranged there is an elastic element (31) projecting into the interior of the chamber (8).

20. Method for multi-stage compression of a gas with a membrane compressor according to one of the Claims 1 to 19, characterized in that by rotating an eccentric or camshaft (18) pistons (13) in cylinders (7) are moved back and forth between bottom and top dead centers,

a pressure difference to a chamber (8), which is separated from the respective cylinder (7) by means of a membrane (5), is generated with a liquid contained in the cylinders (7);

as a result of the pressure difference when the piston (13) moves and the membrane (5) moves towards the bottom dead center gas through a

Gas inlet (9) into the chamber (8) and liquid via a feed line (24, 25, 26, 27) sucked into the cylinder (7) and

due to the pressure difference when the piston (13) moves, with the liquid sucked into the cylinder (7) and the movement of the membrane (5) towards the top dead center, the gas in the chamber (8) is compressed, displaced from it and compressed a subsequent compressor stage (2, 3, 4) or into a gas storage,

backflow of gas and liquid is prevented by means of check valves (28, 33) and compressed gas is supplied through the valve (34) to the subsequent compressor stage or to a gas storage.

21. The method according to claim 20, characterized in that the cylinders (7) of the compressor stages for the compression stroke liquid is supplied in excess.

22. The method according to claim 21, characterized in that at least one cylinder (7) of a compressor stage upon movement of the piston (13) to bottom dead center with a feed pump (16) is fed a metered amount of liquid.

23. The method according to any one of claims 1 to 22, characterized in that compressed gas is cooled between individual compression stages and / or after the last compression stage.