Pumping device

Abstract

A conveying device for fluids with an inlet (12) and an outlet (14) and a conveying part (10) which is connected in between and is actuable by a drive part, characterized in that the conveying part (10) has a fluid-tight media-separating device (16) with a variable chamber volume, which becomes fluidically connected via its receiving space (21) to the inlet (12) or the outlet (14), and which, by means of the drive part, receives fluid via the inlet (12) as part of an intake stroke, increasing the chamber volume, and discharges the received fluid via the outlet (14) as part of a discharging stroke, reducing the size of said chamber volume.

Description

[0001] The invention relates to a conveying device for fluids having the features in the preamble of claim 1.

[0002] WO 2013 / 079222 A2 discloses a delivery device for improving energy efficiency in hydraulic systems, comprising an actuator that operates as a consumer of hydraulic energy in one operating state and as a generator of hydraulic energy in another operating state, and comprising a hydraulic accumulator that can be charged by the actuator to store energy in one operating state and discharged to deliver energy to the actuator in the other operating state. The hydraulic accumulator is a discontinuously adjustable hydropneumatic piston accumulator in which several pressure chambers are formed, which border on different sized active surfaces on the fluid side of the accumulator piston. Furthermore, an actuating arrangement is provided that connects a selected pressure chamber or several selected pressure chambers of the piston accumulator to the actuator, depending on the respective pressure levels prevailing on the gas side of the piston accumulator and at the actuator.

[0003] This makes it possible to recycle energy regardless of the pre-charge pressure on the gas side of the accumulator and regardless of the respective load pressure, because by selecting an appropriately sized effective area, the respective desired pressure level at the accumulator can be used for charging or discharging. This enables optimal energy conversion under all operating conditions. The familiar multi-piston arrangement for the piston accumulator requires seals, such as metallic piston rings or rubber-elastic plastic seals, to seal the individual piston chambers from one another. Due to the high forces and pressures that occur during operation, the additional use of lubricants is usually necessary to keep the frictional forces as low as possible, thus reducing wear and creating a seal that is as leak-free as possible.Nevertheless, leaks cannot be avoided, and friction causes wear on both the individual pistons and the associated sealing material. These wear particles, although usually small, nevertheless lead to contamination of the gases or liquids being pumped, some of which may be extremely pure, which can then only be removed through very complex filtering measures in the fluid flow.

[0004] US 2019 / 0282926 A1 describes a conveying device for fluids with the features in the preamble of claim 1 with an inlet and an outlet and a conveying part arranged therebetween, which can be actuated by a drive part, wherein the conveying part has a fluid-tight media separation device with a variable chamber volume, which with its receiving space establishes a fluid-conducting connection with the inlet or outlet and which, by means of the drive part, takes in fluid via the inlet during a suction stroke while increasing the chamber volume and discharges the absorbed fluid via the outlet during a discharge stroke while reducing this chamber volume.

[0005] Further funding institutions can be found in US 2009 / 0324431 A1, WO 2019 / 007768 A1 and DE 10 2014 217 897 A1.

[0006] Based on this prior art, the invention is based on the object of improving the known solution in such a way that a leak-free conveying device is created with which the introduction of contaminants into the fluid to be conveyed or compressed is avoided.

[0007] This object is achieved by a conveyor device having the features of patent claim 1 in its entirety.

[0008] According to the characterizing part of claim 1, it is provided that the fluid flow, in particular the gas flow, is monitored on the discharge side of the conveying part by means of a contamination sensor.

[0009] The fact that the conveying part has a fluid-tight media separation device with a variable chamber volume, which, with its receiving space, establishes a fluid-carrying connection with the inlet and outlet. This device, by means of the drive part, takes in fluid via the inlet during an intake stroke, increasing the chamber volume, and releases the absorbed fluid via the outlet during a discharge stroke, reducing this chamber volume. This ensures that no leaks occur in the conveying part and that no contamination is introduced into the fluid to be conveyed or compressed. The fluid-tight media separation device ensures that no medium can reach the conveying side for the fluid from the drive side, thus preventing any contamination from entering the transport fluid side.The conveying device according to the invention can be used to transport incompressible fluids, such as any type of liquid, as well as compressible media, for example, in the form of high-purity gases such as hydrogen, which are compressed in the process. The conveying or compression of fluids composed of compressible and incompressible components is also possible. This also prevents the unwanted introduction of a working gas into the liquid side.

[0010] In a preferred embodiment of the conveying device according to the invention, the media separation device is formed from a bellows which is fluidically controlled from the outside by means of the drive part in such a way that the internal chamber volume of the bellows increases during a suction stroke and decreases during a discharge stroke. The bellows used as a media separation device, usually in the form of a conventional folding bellows, is considered in practice to be absolutely media-tight, i.e. no medium can pass through the bellows wall either from the inside to the outside or vice versa. If designed accordingly in stainless steel, the media separation device can also be considered to be resistant to embrittlement in hydrogen applications.Due to the fold design of the bellows, it has a relatively small storage and discharge volume compared to other hydraulic accumulators, such as bladder accumulators; only compared to the elastomeric accumulator bladder can a conveying operation be achieved with high cycle times, whereby in the contracted state of the bellows, the individual bellows folds come into contact with one another, which stabilizes the bellows arrangement as a whole and helps to prevent malfunctions.

[0011] In a further preferred embodiment of the conveying device according to the invention, the drive part comprises a hydraulic working cylinder that can be controlled by means of a hydraulic drive and a main valve. In this way, the control of the conveying part, which can also function as a compressor part, can be controlled using conventional hydraulic components for the drive part. The aforementioned components of the drive part can be standardized and thus easily adapted to the desired conveying and compression performance for the conveying part or compressor part.

[0012] In a further preferred embodiment of the conveying device according to the invention, the hydraulic working cylinder, with its piston-rod unit and a dosing chamber with a predeterminable dosing volume, specifies the intake and discharge stroke for the conveying part, preferably on the piston side, and the actuation of the working cylinder preferably takes place on the rod side via the main valve. The aforementioned dosing volume is virtually incompressible, so that a movement of the hydraulic working cylinder, acting as a so-called pump cylinder, can be transmitted to the media separation device without loss or delay. Particularly for smaller volume flows and lower pressures, the function can also be swapped from the piston side to the rod side. This allows pressure transmission in both directions.

[0013] In a particularly preferred embodiment of the conveying device according to the invention, it is provided that, to maintain a uniform conveying volume flow, an additional conveying part is provided, which performs a discharge stroke while the other conveying part performs an intake stroke, and vice versa. In this way, the conveying device can be operated quasi-continuously, in that one conveying part always ensures the discharge of fluid under pressure, while the other conveying part is loaded with fluid during the intake stroke for the subsequent discharge stroke.

[0014] It is advantageous that the additional delivery section is also connected to the working cylinder, which, forming an additional dosing chamber with a predeterminable dosing volume, has a second piston connected to the piston rod of the first piston for one dosing chamber. In this way, the delivery system with two delivery sections can be operated in a synchronous sequence using only one working cylinder or pump cylinder.

[0015] In a further preferred embodiment of the conveying device according to the invention, it is provided that for the conveyance of gases, the respective conveying section functions as a compressor section, that two compressor sections form a single-stage compressor, and that the interconnection of several single-stage compressors results in a multi-stage compressor. In this way, a low pressure existing on the gas inlet side can be reduced by the first compressor stage to a comparatively higher medium pressure, which in turn is converted to high pressure on the gas outlet side by the second compressor stage.

[0016] In a further preferred embodiment of the conveying device according to the invention, it is provided that at least one dosing unit is present, particularly to compensate for leaks in the working cylinder, which introduces small amounts of dosing volume into or removes it from the respective dosing chamber. By means of the dosing unit, preferably small volumes can be added to the dosing volume of the working or pump cylinder or withdrawn from this dosing volume as required. For this purpose, the respective dosing unit is preferably connected to a supply and discharge unit by means of dosing valves, and the respective dosing unit can be protected by a secondary pressure relief device. By means of the dosing valves, dosing processes can be carried out very precisely using the dosing unit, and the aforementioned secondary pressure relief device, which can preferably consist of a pressure relief valve, serves to protect against overloads.

[0017] Furthermore, it can preferably be provided that the positions of the working cylinder can be detected via an end-position monitor. This allows for functional monitoring of the working or pump cylinder, whereby another form of cylinder monitoring can also be used instead of end-position monitoring.

[0018] In a further preferred embodiment of the conveying device according to the invention, the flow rate is evened out by means of hydraulic accumulators, particularly in the form of medium- and high-pressure gas accumulators. Thus, a uniform volumetric flow rate can be achieved even in gas conveying with only one conveying section with an intermittent conveying stroke.

[0019] In a further preferred embodiment of the conveying device according to the invention, at least one cooling device is provided between individual compression stages. It has been shown that, particularly when using multi-stage compression during the conveying and compression of gases such as hydrogen, the temperature can rise significantly, leading to an unwanted expansion of the gas, which in turn would lead to an increase in the drive power required by the individual conveying or compression components. This can be avoided by the aforementioned intermediate cooling between the compression stages.

[0020] Contamination sensors monitor the fluid flow, especially the gas flow, on the discharge side of each compressor section. If contamination is detected, even if unlikely, the affected section of the conveying system must be shut down immediately so that any contaminated or unusable parts can be replaced during maintenance. Particularly when conveying or transporting high-purity gases, such as hydrogen, no particulate contamination whatsoever must be present in the gas stream for the intended use, for example, in fuel cell operation.

[0021] The compressor solution according to the invention, thanks to its modular design, not only facilitates adaptation to required compressor mass flows by scaling the media separation devices accordingly in terms of size and number, but also allows for easy adjustment of the compression ratios themselves. Furthermore, in the control area, the associated hydraulic control circuit with its components for a multitude of conveying and compressor parts is implemented only once and not multiple times. Accordingly, a preferred use of the conveying device provides for the stepwise compression of hydrogen gas using individual, identically constructed compressor parts. This has no equivalent in the prior art.

[0022] In the following, the conveyor device according to the invention is explained in more detail using exemplary embodiments according to the drawing. In a schematic representation and not to scale, the Fig. 1 Components of a conveyor part of the conveyor device; Fig. 2 a conveyor device with two conveyor parts that are controlled by a common drive part; Fig. 3 the solution according to the Fig. 2 in realization with fluid components; Fig. 4 a sequence of two conveyor devices according to the Fig. 2 forming a complete conveyor system; Fig. 5 the conveyor system realized with individual components according to the basic representation according to the Fig. 4 ; and Fig. 6 and 7 two different types of pollution sensors.

[0023] The Fig. 1 The conveying part, designated as a whole by 10, is fluid-conductingly connected to an inlet 12 and an outlet 14. Furthermore, the conveying part 10 has a media separation device 16 in the form of a bellows, in particular in the form of a folding bellows. The media separation device 16, in the form of a bellows preferably made of metal, hermetically separates the liquid of a metering volume on the outside of the bellows from the fluid to be conveyed or compressed inside the bellows. If the conveying part 10 is used to convey gases, such as hydrogen gas, the conveying part 10 equally functions as the compressor part 10. The folding bellows itself consists of a very thin metal sheet and is designed to be so highly elastic that the pressure applied from the outside and the pressure prevailing inside the bellows differ by less than 0.1 bar in one embodiment.This means that a fluid pressure applied from the outside, and this can easily be a pressure in the order of magnitude of almost 1000 bar, is transferred to the fluid inside the bellows with almost no loss.

[0024] The displacement volume of the media separation device 16 or the bellows is designed such that it is greater than the displacement achieved by a maximum pump cylinder movement of a drive part 18 ( Fig. 2 ) generateable displacement of the dosing volume along with a defined margin of play at the end positions to prevent forced over-expansion of the bellows as a result of a pressure difference occurring across the bellows. To monitor this condition, a monitoring device is provided on the drive part 18, which will be discussed in more detail below, as well as two oppositely arranged end position monitors 20 for the media separation device 16, which can detect any deviations. Such deviations can arise from leaks occurring on the drive part 18, which would generate an increase or decrease in the dosing volume on the delivery part 10. This would inevitably result in a displacement of the bellows position, which in turn could lead to consequential damage to the bellows if its permissible expansion is exceeded.

[0025] The Fig. 1 The media separation device 16 shown essentially performs two functions: Firstly, the separation of the two fluids of the system from each other, namely the pressure fluid used in the dosing volume from the high-purity gas to be conveyed and possibly compressed, and secondly, the actual conveying and compression function.

[0026] For separating the fluid systems, the media separation device 16, in the form of a bellows, allows for hermetic separation. For the conveying and compression functions, the bellows offers highly flexible deformability with a large displacement. Furthermore, during a compression process, very high gas temperatures arise in the gas chamber, i.e., in the interior or receiving chamber 21 of the bellows, depending on the desired compression ratio, which the bellows must withstand without damage. These requirements can be met with an appropriately designed metal bellows.

[0027] For the conveying and compression function, the media separation device 16 is equipped with valves in the form of two counter-acting check valves 22 as so-called compressor valves. To ensure that the media separation device 16 in the form of a bellows can be easily removed for servicing without major gas losses, it has a switchable directional control valve 24 on the inlet 12 side in the associated fluid channel, which, in the closed state, as shown in the illustration according to the Fig. 1 blocks fluid access via the inlet 12 into the interior of the bellows. Since servicing should be carried out as simply and quickly as possible, a defined separating joint 26 is provided for this purpose, which, as a standardizable interface, allows a quick change for the respective media separation device 16. In a preferred embodiment, such a separation point 27 can also run directly above the bellows. A drain device 28 is also installed so that fluids, such as residual gases in the conveying part 10, can be safely drained before any disassembly of the media separation device 16. Each of the two check valves 22 is assigned an independent fluid line as inlet 12 and outlet 14, which leads to the media separation device 16.However, it is also possible (not shown) to provide only a single line leading to the media separation device 16 and branching into a T-shape at the opposite end, with one branch of the branch forming the inlet 12 and the other branch forming the outlet 14. Similar to the check valves 22, a check valve in each associated branch serves to ensure the uninterrupted supply and discharge of fluid and prevents unwanted backflow toward the fluid source during the delivery stroke with the media separation device 16.

[0028] The proper functioning of the media separation device 16 is constantly monitored, in particular by the two signal transmitters 20 of the end position monitoring, which signal the reaching of the corresponding end positions during the stroke of the metal bellows. If the metal bellows assumes its fully extended position at maximum chamber volume, it actuates, in the direction of the Fig. 1 seen, the lower end position monitoring 20 and at a maximum conveying stroke and accordingly minimum chamber volume, the upper end position monitoring 20 is controlled.

[0029] Furthermore, a contamination sensor 30 is accommodated on the outlet side of the conveying part 10, as shown for example in the Fig. 6 und 7 which monitors the tightness of the metal bellows.

[0030] The upper end of the bellows is connected to a partition plate 32, which divides a housing 34 of the conveying part 10 into two separate chambers. The contamination sensor 30 is located in the upper chamber, as well as a tapping point for the discharge device 28 on the inlet side of the conveying part. The second, lower chamber accommodates the bellows, which is hermetically sealed on its underside with a bellows plate 36. An intermediate or fluid chamber 38 is formed between the outer side of the bellows and the inner side of the respective housing part. This intermediate or fluid chamber 38 is connected to the drive part 18 via a fluid-carrying connection 40 and forms the connection for the driving metering volume of the drive part 18 for actuating the conveying or compressor part 10.

[0031] The possible fluid flow directions are shown in the Fig. 1 shown with arrows. If the bellows is extended by means of the drive part 18 and the directional control valve 24 is switched to its fluid-permeable position, the fluid flows through the inlet 12 and the Fig. 1 seen from the right compressor valve 22, the fluid to be conveyed into the receiving space 21 of the bellows. In this respect, an intake stroke is achieved via the media separation device 16. Again by appropriate control of the drive part 18, the bellows plate 36 moves upwards and the bellows volume decreases, so that the fluid stored in the bellows during the intake stroke reaches the outlet 14 of the delivery or compressor part 10 via the contamination sensor 30 and, upon forced opening of the left compressor valve 22. During the corresponding discharge stroke via the outlet 14, the right check or compressor valve 22 is closed, so that fluid cannot inadvertently flow back to the inlet 12 during the discharge stroke. The execution of these intake and discharge strokes can be achieved in rapid succession by means of the drive part 18, which will be explained in more detail below.

[0032] It goes without saying that when the conveyor or compressor part 10 is operated after the Fig. 1 a delivery pause occurs, which is inevitably formed by the intake stroke by means of the bellows via the inlet 12. In this respect, the delivery part 10, or rather the compressor part, only allows intermittent delivery operation. In the embodiment according to the Fig. 2 and 3 In contrast, two conveyor parts 10 are connected in parallel, which are alternately controlled by a common drive part 18. As in Fig. 2 As shown, fluid is supplied to both the one and the other inlet 12 of a conveying part 10 via a common supply line 42. The outlet 14 of each conveying part 10 is in turn connected to a common discharge line 44. In this way, a quasi-continuous conveying operation for the medium to be conveyed or transported can be achieved in that one conveying part 10 always conveys fluid into the discharge line 44, whereas the other conveying part 10 removes fluid from the supply line 42 by means of an intake stroke. If, for example, gas is supplied at low pressure via the supply line 42, a gas outlet under high pressure is achieved by means of the two conveying or compressor parts 10 in the discharge line 44. In this way, high compression ratios of, for example, approximately 1:10 can be achieved.

[0033] The drive part 18 has a hydraulic working or pump cylinder 46, which can be controlled by means of a hydraulic drive 48 and a main valve 50. Furthermore, Fig. 4 a dosing unit 52, which can save a small correction volume in the connecting lines between the pump cylinder 46 and the dosing volumes 54 and 56, respectively, or can take it from these connecting lines. Fig. 3 The drive part 18 is shown in more detail with its individual components. In particular, the drive part 18 has the hydraulically driven working or pump cylinder 46, which is driven by the volume flow of a drivable hydraulic pump 58 as the main pump, wherein the piston-rod unit 60 of the cylinder 46 moves back and forth according to the double arrow depending on the switching position of the main valve 50. The main pump 58 is driven at a variable speed by a motor M and can thus be adapted to the desired delivery and compression performance. The cylinder 46 generates the required power for compressing and further conveying the fluid or gas by pushing the constant metering volume 54, 56, which is located between the cylinder 46 and the respective media separation device 16 of a delivery part 10, back and forth.In addition to the main pump 58, there is also a control pump 62 which can supply various auxiliary functions with hydraulic energy, in accordance with . Fig. 3 the dosing unit 52 as a whole and the pilot control of the main valve 50 in the form of an electromagnetically actuated 4 / 3-way valve.

[0034] For smaller conveying and compressor parts 10, the main valve 50 can also be designed as a single-stage valve, because then only smaller volume flows, for example < 100 l / min, are required. For multi-stage compressors according to the Fig. 4 and 5 , which then have a main pump 58 per compressor stage, but only one stage is always equipped with an additional control pump 62 ( Fig. 5 ), which then also supplies the other stages. Alternatively, the drive part 18 could also comprise a piston engine, for example in the form of an in-line piston pump driven by rotation via a crankshaft (not shown).

[0035] Between the working or pump cylinder 46 and the respective media separation device 16, which are connected to each other via the respective connection 40, there is a fluid volume, referred to as the metering volume 54, 56, which is shifted back and forth between the cylinder 46 and the respective media separation device 16. This metering volume 54, 56 is virtually incompressible, so that a movement of the cylinder 46 is transmitted to the respective media separation device 16 without loss or delay. The respective metering volume 54, 56 is delimited by a piston surface of the piston-rod unit 60, with the rod side connected to the outlet of the main valve 50 via fluid lines. In this respect, the rod of the piston-rod unit 60 divides the cylinder 46 into two rod-side fluid chambers 64 and 66.

[0036] To compensate for leaks in the working or pump cylinder 46, the dosing unit 52 is used, which can add small volumes to the respective dosing volume 54, 56 or withdraw them from this dosing volume. The dosing unit 52 consists of two small, self-contained reciprocating pistons, which can absorb a small, defined displacement volume (preferably < 10 cm 3< ) for movement from one end position to the other and release it on the other side, which is triggered by switching the associated directional valves 68, 70 for metering or metering. The metering unit with reciprocating piston and associated directional valve is in Fig. 3 designated 72 and the corresponding dosing unit 74. The dosing volume 54 or 56, which is to be increased or reduced accordingly, is thus controlled by the associated dosing valve 68 or 70. After completion of a required dosing process, the respective dosing valve 68, 70 can be switched off again. To protect against overload, the dosing volumes 54, 56 are additionally protected by a secondary pressure relief device 76, which consists of a pressure relief valve connected to both dosing volumes 54, 56 via check valves 78. An end position monitor 80 or a stroke measuring device (not shown) of the piston-rod unit 60 is used to monitor the cylinder 46, which interacts with the end position monitor 20 of the media separation device 16 as part of an overall control system.

[0037] As the Fig. 3 Furthermore, the feed pump 62, like the main pump 58, is provided with a primary pressure relief device 82, with a tank accumulator 84 in the form of a conventional hydraulic accumulator being connected to the fluid inlet side for the main pump 58 and the control pump 62. Furthermore, a filter 86 and a cooler 88 are provided on the inlet side for the individual pumps 58, 62. To even out the flow rate, a hydraulic accumulator 90 is connected to the discharge line 44.

[0038] With the inventive solution according to the Fig. 3 The conveying device essentially consists of the drive part 18 and the conveying or compressor part 10, wherein the fluid on the compressor side, usually in the form of a gas to be compressed, is separated from the fluid on the drive side, the metering volume, usually in the form of a hydraulic medium, by the respective media separation device 16 in the form of the bellows. The modular design of the compressor allows for easy scaling to larger, single-stage compressor units as shown in the Fig. 2 , 3 and to multi-level units according to the representations according to the Fig. 4 and 5 .

[0039] In the multi-stage, especially two-stage compressor design according to the Fig. 4 , the funding facility will be Fig. 2 connected in series in fluid terms twice, with a cooling device 92, particularly in the form of a heat exchanger, being introduced between the two compressor stages. The gas supplied via the supply line 42 is in the low-pressure range and is raised to a medium pressure by means of the first compressor upstream of the intercooler 92 as the cooling device. The working cylinder 46 of the first compressor stage acts as a pump cylinder or generator for the relevant medium pressure. After passing through the intercooler 92, the gas reaches the input or inlet side of the second compressor stage with the two delivery or compressor parts 10 via a medium-pressure line 94. Thus, on the output side of the second compressor stage, the gas discharge pressure in a high-pressure line 96 is raised to high pressure. In this way, by means of the two-stage compressor after the Fig. 4 For example, a low gas pressure of 50 bar can be increased to a medium pressure of about 160 bar and a high pressure discharge pressure of 500 bar. Thus, with two-stage compression, compression ratios of 1:3.16 can be expected in both compressor stages. If the two-stage compressor solution is to be used according to the Fig. 4 in the sense of a 3-stage compaction by adding a further single-stage compaction according to Fig. 3 With a compression ratio of less than 1:3 per stage, pressures in the range of 1000 bar can be achieved, especially for hydrogen. Even starting with very low pressures of 15 bar, output pressures of 500 to 600 bar can be achieved with three-stage compression.

[0040] The basic design of a two-stage compressor according to the Fig. 4 is in component construction in the Fig. 5 reproduced, whereby the statements made so far regarding the individual components also apply to the multi-stage compressor according to the Fig. 5 This solution differs from the previous solution according to the Fig. 3 in that the hydraulic accumulator 90 connected to the medium-pressure line 94 forms a medium-pressure gas accumulator, and the accumulator 90, which is connected to the high-pressure line 96, forms the high-pressure gas accumulator for the entire device. Both medium-pressure and high-pressure gas accumulators serve to equalize the flow rate. If Fig. 5 For the individual conveying and compressor parts 10 electrical cables are shown, these relate to the sensor tap for the end position monitoring 20 and an electronic evaluation of the contamination sensor 30.

[0041] Embodiments of such a contamination sensor 30 are described in the Fig. 6 und 7 shown in more detail. As already explained, leaks at the separation points between the metering volume 54, 56 and the respective gas volume to be pumped can cause high consequential costs. Accordingly, a contamination sensor 30 is arranged directly after the metal bellows in the line for the outflowing gas streams on the outlet 14 side. This sensor monitors the purity of the gas.

[0042] Such contamination sensors 30 can be constructed according to various principles, whereby in the present case at least two functions should be fulfilled: 1. Detecting contamination at the very beginning of contamination development; and 2. Capturing initial contamination with a filter.

[0043] If contamination is detected, the corresponding part of the system should be able to be shut down immediately in order to eliminate the cause of contamination and replace the contaminated parts, for which the system operation only needs to be interrupted for a short time. The technical solution of a contamination sensor 30 according to the Fig. 6 Contamination of the clean surface of a filter fleece 98 causes a significant color change, which is detected by a light sensor. For this purpose, a light source designated by reference numeral 100 sends light rays onto the upper side of the filter fleece 98, which thus forms a surface sensitive to contamination, and reflected light rays are detected by a light sensor 102. The light beam guide is in the Fig. 6 as well as the direction of flow through the contamination sensor 30, which is indicated by arrows. In order to prevent the filter fleece 98 from being pulled out of the sensor housing 103 on the outlet side during the flow, it is supported on a reinforced base layer 104.

[0044] The contamination sensor 30 after the Fig. 7 works with a similar structure; but now a pressure difference is measured when flowing through the filter fleece 98 by means of two pressure measuring devices 106 in front of and behind the filter fleece 98. If a corresponding increase in the flow resistance is detected due to contamination, a signal is emitted. The pressure difference measurement by means of the pressure measuring device 106 takes place with a circuit output, and the filter fleece 98 can be a soakable filter mat, which, when soaked with oil, creates a higher flow resistance than the pure filter fleece 98 after the Fig. 6 .

[0045] With both sensor principles, the filter fleece 98 which triggered the signal due to contamination can be replaced so that the respective sensor 30 can continue to be used if necessary.

[0046] For higher compression ratios, for example ≥ 4, multi-stage compressors are generally used according to the examples shown in the Fig. 4 and 5 This is because the thermodynamics of compression require excessive drive power at higher compression ratios. Gas temperatures also rise so high that special materials are required. A multi-stage compressor with intercooling between the compressor stages requires less drive power, which is extremely energy-efficient.

[0047] The conveying system is particularly suitable for hydrogen applications; however, it can also be used to transport and convey other fluids, including those that are completely incompressible and therefore not compressed during conveyance.

Claims

1. Conveying device for fluids with an inlet (12) and an outlet (14) and a conveying part (10) which is connected therebetween and can be actuated by a drive part (18), wherein the conveying part (10) has a fluid-tight media-separating device (16) with a variable chamber volume, which becomes connected in a fluid-conducting manner via its receiving chamber (21) to the inlet (12) or the outlet (14), and which, by means of the drive part (18), receives fluid via the inlet (12) as part of an intake stroke, increasing the chamber volume, and discharges the received fluid via the outlet (14) as part of a discharge stroke, reducing the size of said chamber volume, characterised in that the fluid flow, in particular gas flow, is monitored by means of a contamination sensor (30) on the discharge side of the conveying part (10).

2. Conveying device according to claim 1, characterised in that the media-separating device (16) is formed of a bellows which is fluidically controlled from the outside by means of the drive part (18) in such a manner that the inner chamber volume of the bellows increases during an intake stroke and decreases during a discharge stroke.

3. Conveying device according to either claim 1 or claim 2, characterised in that the drive part (18) has a hydraulic working cylinder (46) which can be controlled by means of a hydraulic drive (48) and a main valve (50).

4. Conveying device according to claim 3, characterised in that the hydraulic working cylinder (46) with its piston-rod unit (60) uses a metering chamber of predefinable metering volume (54) to predefine the intake and discharge stroke for the conveying part (10), preferably on the piston or rod side, and in that the working cylinder (46) is actuated via the main valve (50), preferably on the rod or piston side.

5. Conveying device according to one of the preceding claims, characterised in that, in order to obtain a homogenised conveying volume flow, a further conveying part (10) is provided which performs a discharge stroke, while the other conveying part (10) performs an intake stroke and vice versa.

6. Conveying device according to claim 5, characterised in that the further conveying part (10) is likewise connected to the working cylinder (46), which has a second piston that is connected to the piston rod by way of the first piston for the one metering chamber, thus forming a further metering chamber of predefinable metering volume (56).

7. Conveying device according to one of the preceding claims, characterised in that, for conveying gases, the respective conveying part (10) acts as a compressor part, in that two compressor parts (10) form a single-stage compressor and in that the interconnection of a plurality of single-stage compressors (10) results in a multi-stage compressor.

8. Conveying device according to either claim 3 or claim 4, characterised in that, in particular to compensate for leaks at the working cylinder (46), at least one metering unit (52) is present, which introduces small quantities of metering volume into the respective metering chamber of the working cylinder (46) or discharges them therefrom.

9. Conveying device according to claim 8, characterised in that - the respective metering unit (52) is connected to a metered inflow (72) and metered outflow unit (74) by means of metering valves (68, 70); - the respective metering unit (52) is protected by a secondary pressure protection device (76); - positions of the working cylinder (46) can be detected via a monitoring device (80); - homogenisation of the conveying flow takes place by means of hydraulic accumulators (90), in particular in the form of medium and high-pressure gas accumulators; and / or - at least one cooling device (92) is inserted between individual compressor stages (10).

10. Use of a conveying device according to one of the preceding claims, characterised in that individual compressor parts (10) of identical construction are used for compression of gases, such as hydrogen, in stages.

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