Piston compressor

Abstract

The invention relates to a piston compressor (1) for compressing gases, comprising at least one cylinder (6), at least one piston (5) which is mounted in a respective cylinder (6) such that a respective piston (5) and a respective cylinder (6) delimit a compression chamber (29) for compressing the gas, an inlet valve (19) for a respective compression chamber (29), an outlet valve (20) for a respective compression chamber (29), at least one annular groove (15) formed in the piston (5) at least one piston ring (16), a respective piston ring (16) being provided in each annular groove (15), and a respective radial annular chamber (112) formed on the radial inner face (110) of each piston ring (16). The piston compressor is designed to apply a compressive pressure which is directed radially outwards by means of the gas in the compression chamber (29) using a gas-conducting connection between the compression chamber (29) and the respective radial annular chamber (112) in order to seal the compression chamber (29) between the radial outer face (109) of the respective piston ring (16) and the respective cylinder (6) by means of the radially outwardly directed compressive pressure applied to the radial inner face (110) of the respective piston ring (16). At least one piston ring channel (106) is formed in the respective piston (5) as a gas-conducting connection from the compression chamber (29) into the at least one radial annular chamber (112) so that the pressure of the gas to be compressed in the compression chamber (29) acts on the radial outer face (109) of the respective piston ring (16) through the at least one piston ring channel (106).

Description

[0001] Description

[0002] title

[0003] piston compressor

[0004] The present invention relates to a piston compressor according to the preamble of claim 1 and a piston compressor system according to the preamble of claim 14.

[0005] State of the art

[0006] Piston compressors are used in a wide variety of technical applications to compress gases. In a piston compressor, a piston performs an oscillating motion. The piston is mounted on a cylinder. An inlet valve introduces gas into the compression chamber, and an outlet valve expels the gas from the compression chamber. The compression chamber is bounded at one end, opposite the piston, by a cylinder head. The inlet and outlet valves are generally integrated into the cylinder head. The piston's oscillating motion is achieved by a mechanism. This mechanism can be, for example, a crankshaft assembly with a crankshaft and connecting rod, or a roller bearing with a roller and a drive shaft with at least one cam. The mechanism is located within a lubrication chamber.The lubrication chamber is supplied with a lubricant, such as lubricating oil, to lubricate the moving components of the mechanism. The mechanism is driven, for example, by an electric motor. The piston performs the oscillating motion between top dead center and bottom dead center, and the difference in volume of the compression chamber between the piston's top and bottom dead centers defines the stroke volume. The dead volume of the compression chamber is the volume of the compression chamber at the piston's top dead center. A ring groove is formed in the piston, and a piston ring is positioned in this groove. A radial annular space exists between the radial inner surface of the piston ring and the radial outer surface of the piston.Additionally, a suitably dimensioned axial clearance exists between the piston ring and the piston, creating an axial annular space between the piston and the piston ring. The pressure of the gas in the compression chamber acts through this axial annular space onto the radial annular space between the radial inner surface of the piston ring and the radial outer surface of the piston. The piston ring is essentially unpreloaded, so the necessary radial pressure force between the radial outer surface of the piston ring and the piston guide and cylinder is primarily generated by the gas in the radial annular space.The axial annular space thus forms a gas-conducting connection between the compression chamber and the radial annular space, so that, due to the pressure of the gas in the compression chamber, the radial outer surface of the piston ring rests against the cylinder with a corresponding radial pressure force. However, due to the translational movement between the piston ring and the cylinder, a partial plastic deformation of the piston ring occurs at a radial outer end region, resulting in plastic deformation in the radial direction between the radial outer surface of the piston and the cylinder. This plastic deformation essentially blocks or closes the gas-conducting connection, namely the axial annular space, so that the pressure of the gas in the compression chamber no longer acts on the radial annular space between the piston ring and the piston in the radial direction.This significantly reduces the sealing of the compression chamber with the piston ring and greatly reduces the efficiency of the piston compressor.

[0007] EP 0 541 482 B1 discloses a piston compressor for oil-free compression of gases, comprising at least one cylinder and a piston guided therein, which is provided with at least one slotted, so-called trapped piston ring housed in an annular groove on the piston, the circumferential surface of which, facing away from the inner surface of the cylinder, delimits a space of the annular groove acted upon by the pressure of the gas in the compression chamber of the cylinder, and which, starting from this circumferential surface, has two radial, mutually parallel limiting surfaces, the surface facing the compression chamber of which extends over a part of the radial ring width, wherein the piston ring is guided slidably with its two parallel limiting surfaces on corresponding surfaces of the annular groove, wherein the remaining surface of the piston ring facing the compression chamber, starting from the circumferential surface facing the inner surface of the cylinder, is designed as a wedge surface.which extends at an angle of 5 to 15° to a parallel to the boundary surface facing the compression space, up to that boundary surface.

[0008] DE 2020699 A1 discloses a reciprocating piston compressor with a single- or multi-stage design of the pistons and / or cylinders, wherein at least one bellows, generalized as at least one diaphragm, is arranged between each piston and the crankcase. The attachment of the bellows to the rest of the reciprocating piston compressor with an intermediate piece disadvantageously fails to ensure a complete hermetic separation of the crankcase from the compression chamber and does not allow for easy assembly and disassembly of the bellows.

[0009] Disclosure of the invention

[0010] Advantages of the invention

[0011] A piston compressor according to the invention for compressing gases, comprising at least one cylinder, at least one piston mounted in each cylinder, such that each piston and each cylinder define a compression chamber for compressing the gas, an inlet valve for each compression chamber, an outlet valve for each compression chamber, at least one annular groove formed in the piston, at least one piston ring and in each annular groove a piston ring is arranged and a radial annular space is formed on a radial inner surface of each piston ring for applying a radially outwardly directed pressure force by means of the gas in the compression chamber with a gas-conducting connection between the compression chamber and each radial annular space.To achieve a seal of the compression chamber between a radial outer surface of each piston ring and the cylinder by means of the radially outward-directed pressure force applied to the radial inner surface of each piston ring, preferably at least one piston ring channel is formed in each piston as a gas-conducting connection from the compression chamber to the at least one radial annular space, so that the pressure of the gas to be compressed in the compression chamber acts through the at least one piston ring channel on the radial outer surface of each piston ring. Advantageously, the pressure of the gas in the compression chamber thus always and reliably acts on the annular space, so that even in the event of plastic deformation at a radial outer end region of the piston ring, the corresponding supply of gas from the compression chamber to the radial annular space is always ensured.

[0012] In another variant, at least one piston ring channel is essentially aligned in a direction parallel to a longitudinal axis of the cylinder, particularly with a deviation of less than 30°, 20°, or 10°. The piston ring channel thus has a small minimum length for the smallest possible dead space volume in the compression chamber.

[0013] In a further embodiment, at least one piston ring channel, in particular exclusively, is straight. This makes it particularly easy to machine the piston ring channel by drilling.

[0014] In a supplementary embodiment, the flow cross-sectional area of ​​the at least one piston ring channel is essentially identical, in particular with a deviation of less than 30%, 20%, or 10%. The essentially identical flow cross-sectional area of ​​the piston ring channel ensures that essentially no turbulence, and thus no unnecessary pressure losses, develop in the piston ring channel during the gas flow through it.

[0015] Preferably, the axial clearance, in particular the extension of an axial annular space between the piston ring and the piston in the axial direction, between each piston ring and the piston at a temperature of 20°C, is less than 500 pm, 300 pm, 200 pm, 100 pm, 50 pm, 10 pm, or 5 pm. The small, negligible axial clearance between each piston ring and the piston means that the volume of the axial annular space is negligible, and thus, advantageously, the additional dead space volume for supplying the piston ring with gas from the compression chamber is determined essentially only by the volume of the radial annular space and the piston ring channel.Additionally, the radial annular space is essentially sealed in the radial direction by means of a gap seal in the axial direction between the piston and the piston ring, so that the gas pressure acting in the radial annular space through the piston ring channel in the compression chamber cannot escape, for example, into a diaphragm space. This reliably ensures a sufficiently high gas pressure in the radial annular space to seal the gap seal in the radial direction between the radial outer surface of the piston ring and the cylinder.

[0016] In a further embodiment, each piston is designed in two parts: a first piston part and a second piston part. This allows the piston to be advantageously optimized with respect to its geometry and / or material for compressing gases. For example, the first piston part, which exclusively defines the compression chamber, is made of a material optimized for gas compression, and the second piston part, to which the diaphragm is directly or indirectly attached, is optimized with respect to its material for a welded connection, either directly or indirectly, between the second piston part and the diaphragm. When replacing the diaphragm, it is not necessary to replace the entire piston, but only the second piston part to which the diaphragm is directly or indirectly attached by a weld; the first piston part can continue to be used.

[0017] In another variant, a ring groove is formed between the first and second piston parts due to the geometry of the first and second piston parts, and a piston ring is arranged in the ring groove.

[0018] In an additional embodiment, the piston compressor comprises at least one mechanism with which the at least one piston is mechanically connected for an oscillating movement of the at least one piston. In a further embodiment, the piston compressor comprises at least one lubrication chamber in which the at least one mechanism is at least partially arranged and in which the at least one mechanism can be lubricated with a lubricant.

[0019] Preferably, the piston compressor comprises at least one diaphragm, and with the at least one diaphragm, a lubrication chamber is separated from each compression chamber.

[0020] In a supplementary variant, at least one membrane is designed as at least one bellows.

[0021] In particular, each diaphragm divides the cylinder compartment, bounded by each cylinder, each piston, and preferably each flange plate, into an inner diaphragm space and an outer diaphragm space, especially in the radial direction. The gas to be compressed, which escapes from the compression chamber at the gap seal between the piston guide and the piston, thus enters exclusively the outer diaphragm space. Lubricating oil from the lubrication chamber at the piston rod's sliding bearing thus enters exclusively the inner diaphragm space. Advantageously, this prevents lubricating oil from being carried into the compression chamber, and additionally, the compressed gas in the outer diaphragm space can be discharged into the environment or fed back to the inlet valve for reuse of the leakage at the gap seal between the piston and the piston guide on the cylinder.

[0022] Preferably, the stroke of each piston between its top and bottom dead center is less than 30%, 10%, 5%, or 3% of the relevant extension of the at least one diaphragm, in particular the at least one bellows, along a longitudinal axis of the cylinder. The diaphragm thus exhibits minimal expansion and compression during the piston's stroke, resulting in a long service life due to the low mechanical stress.A piston compressor system according to the invention for compressing gases, comprising a piston compressor with at least one piston and with at least one mechanism with which the at least one piston is in mechanical operative connection for an oscillating movement of the at least one piston, a lubrication system with at least one lubricating oil line, a lubricating oil reservoir and a delivery device for lubricating lubricating oil for lubricating the at least one mechanism arranged in a lubrication chamber, a drive motor for the piston compressor, a container with the gas to be compressed, a container with the compressed gas, wherein the piston compressor is designed as a piston compressor as described in this patent application.

[0023] In another embodiment, a throttle channel is formed from the lubrication chamber into the diaphragm interior for directing lubricating oil into the diaphragm interior, and a drain channel is formed from the diaphragm interior into the lubricating oil line for directing lubricating oil from the diaphragm interior into the lubricating oil line and / or into the lubricating oil reservoir. The flow cross-sectional area of ​​the throttle channel is smaller than the flow cross-sectional area of ​​the drain channel; preferably, the flow cross-sectional area of ​​the throttle channel is smaller than 70%, 50%, 30%, or 10% of the flow cross-sectional area of ​​the drain channel. This allows lubricating oil to be advantageously directed into the diaphragm interior for lubrication and cooling of the diaphragm interior and the sliding bearing of the piston rod.

[0024] Preferably, a first end of the at least one piston ring channel opens into the compression chamber, so that the gas to be compressed can be introduced from the compression chamber through the first end into the at least one piston ring channel. A second end of the at least one piston ring channel preferably opens into the axial and / or radial annular space, so that the gas to be compressed can be discharged from the piston ring channel into the axial and / or radial annular space at the second end. Preferably, if the at least one piston ring channel opens into the axial annular space, the gas to be compressed flows first into the axial annular space and then from the axial annular space into the radial annular space. In a further embodiment, the at least one piston ring channel formed in each piston opens into the annular groove at its at least one second end.

[0025] In an additional variant, several piston ring channels are formed on each piston, which open at the second ends into only one ring groove and / or into the, in particular only one and / or identical, axial and / or radial annular space.

[0026] In an additional variant, several piston ring channels are formed on each piston, which open at the second ends into several different ring grooves and / or into several and / or different axial and / or radial annular spaces.

[0027] In a further embodiment, the radial distance of the piston ring channel in the radial direction to the central longitudinal axis of the cylinder is smaller, in particular always smaller, than the radial distance of the radial inner side of the piston ring to the central longitudinal axis of the cylinder.

[0028] In a supplementary embodiment, at least one piston ring is made of metal and / or plastic.

[0029] In an additional variant, the first piston part and the second piston part are connected to each other by a form-fit and / or force-fit and / or material-fit connection.

[0030] In a supplementary embodiment, the first piston part and the second piston part are connected to each other by a screw connection.

[0031] Preferably, a bolt with an external thread is formed on one piston part, in particular the first piston part, and a bore with an internal thread is formed on another piston part, in particular the second piston part, and the external thread of the bolt is screwed into the internal thread of the bore for connecting the first piston part to the second piston part. Due to the screw connection between the first piston part and the second piston part, one piston part can be easily replaced for maintenance purposes.

[0032] In an additional embodiment, at least one ring groove is formed in the first piston part and a piston ring is arranged in each of the at least one ring groove.

[0033] Advantageously, at least one ring groove is formed in the second piston part, and a piston ring is arranged in each of the at least one ring groove.

[0034] In another embodiment, the first piston part is a part facing the compression chamber, and the second piston part is a part facing the mechanism. Preferably, a first fictitious cutting plane perpendicular to the longitudinal axis of the piston and / or the cylinder and / or the piston rod intersects only the first piston part, and a second fictitious plane perpendicular to the longitudinal axis of the piston and / or the cylinder and / or the piston rod intersects only the second piston part.

[0035] In an additional embodiment, each piston limits the compression chamber exclusively at the first piston part.

[0036] In a supplementary embodiment, the maximum axial extension of the second piston part is greater than the maximum axial extension of the first piston part; preferably, the maximum axial extension of the second piston part is greater than 1.2 times, 1.5 times, or 2 times the maximum axial extension of the first piston part.

[0037] In another variant, each radial annular space is limited in the radial direction by the piston ring and the piston, in particular by a pin of the first piston part.

[0038] In another variant, a connecting channel is formed from the membrane interior to the environment, particularly in the flange plate, to maintain an ambient pressure in the membrane interior, and preferably the piston compressor and / or the piston compressor system does not have a throttle channel and / or a drain channel for passing lubricating oil from a lubricating oil circuit through the membrane interior.

[0039] In another variant, at least one membrane is used to fluid-tightly separate each lubrication chamber from each compression chamber.

[0040] In a supplementary embodiment, the membrane interior is sealed fluid-tight from the membrane exterior in each piston compressor.

[0041] In a further embodiment, the first piston part and the second piston part are at least partially, and in particular completely, made of a different material.

[0042] In another embodiment, the first piston part and the second piston part are connected to each other by a bayonet connection and / or a snap-fit ​​connection.

[0043] Preferably, the material-bonded connection between the first piston part and the second piston part is a welded connection and / or an adhesive connection.

[0044] In another embodiment, the number of folds in the bellows is greater than 5, 10, 30, 50, 100 or 200.

[0045] In a supplementary variant, the piston and piston rod are aligned coaxially and / or concentrically to each other.

[0046] In an additional variant, the dead volume of each compression chamber is less than 10%, 5%, 3%, or 2% of the stroke volume of that compression chamber. Advantageously, the piston compressor can thus achieve a high pressure of the gas to be compressed with a small piston stroke, using a mechanism with a shaft having at least one cam and a roller.

[0047] In a further embodiment, the at least one sealing ring and / or the at least one fastening ring have an arbitrary shape in a section perpendicular to the longitudinal axis of the cylinder, in particular circular or rectangular, in particular square, or elliptical.

[0048] In a supplementary embodiment, the at least one diaphragm, in particular the at least one bellows, is arranged at least partially, in particular completely, between the piston and the mechanism in the direction of a longitudinal axis of the cylinder.

[0049] In a further embodiment, the at least one membrane, in particular the at least one bellows, is essentially cylindrical in shape, especially in the area inside the at least one cylinder.

[0050] In a supplementary variant, at least one piston with a piston rod is in mechanical operative connection with the mechanism.

[0051] Ideally, at least one cylinder includes at least one cylinder head.

[0052] In an additional embodiment, the roller comprises a cylindrical roller with a central bore, and a bearing pin is arranged in the central bore. An annular gap is formed between the cylindrical roller and the bearing pin, and this annular gap is lubricated. The axial ends of the bearing pin are supported, for example, by a sliding bearing on the roller shoe.

[0053] In a further embodiment, the axial extent of the at least one membrane is greater than 5 times, 10 times, 20 times, or 30 times the thickness of the at least one membrane. The axial extent of the at least one membrane is thus significantly greater than the thickness of the membrane.

[0054] In an additional embodiment, the membrane is made of metal and / or plastic. Preferably, the plastic of the membrane is an elastomer. The membrane is flexible to accommodate the piston's stroke movements. Preferably, the membrane is made of several layers, in particular layers of different materials such as metal and / or plastic. One layer, for example, a thin layer of a metal, e.g., aluminum foil, reduces the permeation of substances through the membrane. The membrane has a very low permeation coefficient, especially for lubricants. Q = P * F * t * Ap / d. Here, Q is the amount of gas or vapor that permeates through a layer of area F and thickness d in time t when the pressure difference of the permeant before and after the layer is Ap. The gas permeability for oxygen is given by [insert value here]. 3 / m 2The membrane's d-bar is preferably less than 30, 10, 1, or 0.1. The gas permeability for hydrogen is measured in cm. 3 / m 2 The d*bar of the membrane is preferably less than 50, 10, 1 or 0.2.

[0055] In another embodiment, the cylinder has a longitudinal axis. The longitudinal axis of the cylinder corresponds to the direction of movement of the piston mounted in the cylinder.

[0056] The mechanism is appropriately formed by a roller shoe with a running wheel and a drive shaft with cams.

[0057] In another embodiment, the mechanism is formed by a crankshaft and a connecting rod as a piston rod.

[0058] In an additional variant, the piston compressor includes an electric motor to drive the compressor. For example, the electric motor drives the drive shaft with cams and / or the crankshaft.

[0059] The pressure that can be generated by the piston compressor is in the range of 100 bar to 1000 bar.

[0060] Brief description of the drawings

[0061] Exemplary embodiments of the invention are described in more detail below with reference to the accompanying drawings. These show:

[0062] Fig. 1 shows a cross-section of a piston compressor for compressing a gas, Fig. 2 shows a section AA according to Fig. 1 of a roller with roller shoe and a drive shaft,

[0063] Fig. 3 shows an enlarged partial cross-section of the piston compressor according to Fig. 1 ,

[0064] Fig. 4 shows an enlarged partial cross-section of the piston and cylinder shown in Fig. 3,

[0065] Fig. 5 shows a further enlarged partial cross-section of the piston compressor according to Fig. 1 ,

[0066] Fig. 6 shows a cross-section of two piston compressors for compressing a gas with two cylinder housings and

[0067] Fig. 7 shows a highly simplified representation of a compressor system.

[0068] Embodiments of the invention

[0069] Figure 1 shows a cross-section of a piston compressor 1 for compressing gases in a first embodiment. The piston compressor 1 serves to compress gases, e.g. hydrogen or air, under high pressure.

[0070] The pressure that can be generated by the piston compressor 1, for example, lies in a range between 100 and 1000 bar.

[0071] The piston compressor 1 has a drive shaft 2 with two cams 3, which rotates about an axis of rotation 26. The drive shaft 2 is driven by an electric motor (not shown). The axis of rotation 26 lies in the plane of Fig. 1 and is perpendicular to the plane of Fig. 2. A piston 5 is mounted in a cylinder 6, i.e., a piston guide 7 of the cylinder 6, which is formed by a cylinder housing 8. Circumferential annular grooves 15 are formed on a radial outer surface of the piston 5. A piston ring 16 is arranged in each of the annular grooves 15. The piston 5 is formed in two parts, with a first piston part 5a and a second piston part 5b. A compression chamber 29 is bounded exclusively by the first piston part 5a.The maximum axial extension of the second piston part 5b is significantly larger than the maximum extension of the first piston part 5a; for example, the maximum axial extension of the second piston part 5b is greater than 2, 3, or 5 times the maximum extension of the first piston part 5a. The ring grooves 15 with the piston rings 16 are formed in the second piston part 5b and between the first piston part 5a and the second piston part 5b. The first piston part 5a is positively and / or frictionally attached to the second piston part 5b, in particular by screwing a bolt 86 or fitting 86 with an external thread formed on the first piston part 5a into a bore 87 with an internal thread on the second piston part 5b as a screw connection 88. Instead of the screw connection 88 (Fig.3 and 4) a bayonet connection, snap-fit ​​connection, or a material-bonded connection, such as a welded or adhesive bond (not shown), may also be present for the connection between the first and second piston parts 5a, 5b. The compression chamber 29 is bounded by the cylinder housing 8 with cylinder head 17 and the piston 5, i.e., the first piston part 5a. The end 18 of the cylinder head 17 is the portion of the cylinder head 17's surface that bounds the compression chamber 29 and does not function as and / or form a cylinder 6. The compression chamber 29 is opened into an inlet channel 22 with an inlet valve 19 and an outlet channel 24 with an outlet valve 20. The gas flows into the compression chamber 29 through the inlet channel 22 with an inlet opening 21 and flows out of the compression chamber 29 under high pressure through the outlet channel 24 with an outlet opening 23. The inlet valve 19, e.g.A check valve is designed such that only gas can flow into the compression chamber 29, and the outlet valve 20, e.g., a check valve, is designed such that only gas can flow out of the compression chamber 29. The volume of the compression chamber 29 is changed by an oscillating stroke movement of the piston 5. The piston 5 is indirectly supported on the drive shaft 2 by a piston rod 14. The piston 5 and the piston rod 14 are aligned coaxially and / or concentrically with each other. A roller shoe 9 with a roller 10 is attached to the end of the piston rod 14. The roller 10 can perform a rotational movement, the axis of rotation 25 of which lies in the plane of the drawing according to Fig. 1 and is perpendicular to the plane of the drawing in Fig. 2. The drive shaft 2 with at least one cam 3 has a shaft rolling surface 4 and the roller 10 has a roller rolling surface 11.

[0072] The roller running surface 11 of the roller 10 rolls on the shaft rolling surface 4 of the drive shaft 2 at a contact surface 12 with the two cams 3. The roller shoe 9 is mounted as a sliding bearing in a roller shoe bearing formed by the cylinder housing 8. A spring 27, i.e., a coil spring 27, as an elastic element 28, which is clamped between a flange plate 43 and the roller shoe 9, exerts a compressive force on the roller shoe 9 so that the roller running surface 11 of the roller 10 is in constant contact with the shaft rolling surface 4 of the drive shaft 2. The spring 27, as the elastic element 28, rests on the roller shoe 9 and the flange plate 43, so that the flange plate 43 acts to support the elastic element 28. The roller shoe 9, the piston rod 14, and the piston 5 thus jointly perform an oscillating stroke motion. The roller 10 is mounted in the roller shoe 9 by means of a sliding bearing 13.The roller shoe 9 with roller 10 and the drive shaft 2 with cam 3 thus function as a mechanism 40 for generating the oscillating movement of the piston 5.

[0073] The inlet valve 19 and the exhaust valve 20 are installed or integrated in the cylinder head 17. The cylinder head 17 is part of the cylinder 6 or the cylinder housing 8. The cylinder head 17 is fastened to the cylinder 6, and thus also to the cylinder housing 8, by means of fixing elements 38 in the form of screws 39. A portion of the surface 18 of the cylinder head 17 forms a surface 18 or end 18, which delimits the compression chamber 29. The inlet valve 19 comprises a valve piston 30, an elastic element 35 in the form of a spring 36, and a support element 37 for the spring 36. In a closed position of the valve piston 30, the valve piston 30 rests fluid-tight on a valve seat 32 that rotates completely in the tangential direction (Fig. 1). The exhaust valve 20 comprises, in an analogous manner, a valve piston 31 for the exhaust valve 20, the elastic element 35 as the spring 36 and the support element 37 for the spring 36 (Fig. 1).The spring 36 of the exhaust valve 20 rests on a valve seat 33 in the closed position of the exhaust valve 20. The valve seat 32 for the intake valve 19 and the valve seat 33 for the exhaust valve 20 are formed as correspondingly shaped geometries on the cylinder head 17. The intake valve 19 and the exhaust valve 20 with the valve pistons 30, 31 are pneumatically actuated. Due to the pressure change in the compression chamber 29 during the stroke of the piston 5, the intake valve 19 is opened and the exhaust valve 20 is closed when the volume of the compression chamber 29 increases, and conversely, when the volume of the compression chamber 29 decreases, the intake valve 19 is opened and the exhaust valve 20 is closed.

[0074] The piston 5 is mounted on the piston guide 7 of the cylinder 6 and performs an oscillating translational movement in the direction of a longitudinal axis 41 of the cylinder 6. The mechanism 40 is arranged in a lubrication chamber 44, which is bounded by a closed housing 45 for the mechanism 40 and the lubrication chamber 44. The closed housing 45 is only partially shown in Fig. 1. The mechanism 40 is lubricated in the lubrication chamber 44 with a lubricant, for example, lubricating oil or fuel. The lubricant is necessary because the bearings of the moving components are designed as sliding bearings. The piston compressor 1 compresses, for example, hydrogen for a fuel cell or air or oxygen for breathing in the compression chamber 29. The gas to be compressed must therefore not be contaminated with the lubricant from the lubrication chamber 44, even in very small quantities.The bearing of the radial outer side of the piston 5 on the piston guide 7 of the cylinder 6 with the piston rings 16 as a gap seal does not allow a complete hermetic separation of the lubrication chamber 44 from the compression chamber 29 with the gas to be compressed.

[0075] For this reason, the lubrication chamber 44 is hermetically completely separated and sealed from the compression chamber 29 by a diaphragm 34, forming a bellows 34. The bellows 34, as the diaphragm 34, is made of metal and / or plastic. The plastic is, in particular, an elastomer. The axial extension of the diaphragm 34 is significantly greater than its thickness. Between the cylinder housing 8 and a housing 45 for the mechanism 40, the ring- and disc-shaped flange plate 43 is arranged in the direction of the longitudinal axis 41 of the cylinder 6. The flange plate 43 serves to transmit forces acting on the cylinder housing 8 to the housing 45 for the lubrication chamber 44 and the mechanism 40. A lower axial end region of the bellows 34, as the diaphragm 34, is fixed to an annular fastening element 49, as a sealing ring 46 made of metal, with a material-bonded connection 52, as a welded connection 53 (Figs. 1 and 4).The fastening element 49, also known as the sealing ring 46, has an L-shaped cross-section with a first leg 59 extending substantially in the radial direction 57 and a second leg 60 extending substantially in the axial direction 56. The first leg 59 forms a first ring 59, and the second leg 60 forms a second ring 60. The weld 53 is preferably produced by laser welding. The weld 53 extends tangentially 58 completely around the circumference between the bellows 34 and the annular fastening element 49, which is the sealing ring 46, at an axial end of the second ring 60 facing the compression chamber 29. Thus, the weld 53, forming a fluid-tight, metallurgical connection 52, provides a hermetic separation between the lubrication chamber 44 and the compression chamber 29.The material-bonded connection 52 thus also forms a sealant 42 and a fastening element 47. An axial direction 56 is aligned in the direction of the longitudinal axis 41 of the cylinder 6. A radial direction 57 is aligned perpendicular to the longitudinal axis 41. The diameter of the annular fastening element 49 is significantly larger in the radial direction 57 than in the axial direction 56. The annular fastening element 49 on the first ring 59 is positively clamped between the cylinder housing 8 and the flange plate 43 by means of a compressive force. Thus, the cylinder housing 8 and the flange plate 43 form a fastening component 50 for the positive clamping of the fastening element 49 by means of a compressive force.In addition, the fastening element 49 is positively locked to the cylinder housing 8 and the flange plate 43 due to the geometry of the fastening element 49, the cylinder housing 8 and the flange plate 43, in particular in the radial direction 57 and in the axial direction 56.

[0076] The flange plate 43 is screwed to the housing 45 for the mechanism 40 by means of fixing elements 38 in the form of screws 39. Due to the design geometry of the piston compressor 1, a lubricant and / or gas would also flow radially 57 along gaps 51 and / or contact surfaces 51 from the space inside and outside the bellows 34 (membrane inner space 61 and membrane outer space 62), the compression chamber 29, and the lubrication chamber 44 to the outside. The gap 51 is formed between the fastening element 49 and the flange plate 43, between the fastening element 49 and the cylinder housing 8, between the flange plate 43 and the housing 45 for the mechanism 40 and for the lubrication chamber 44, and between the cylinder head 17 and the cylinder housing 8 (Figs. 1 and 4). For this reason, a groove 55 is formed in the cylinder housing 8, the flange plate 43, and the housing 45. The cylinder housing 8 has two grooves 55 formed.Each groove 55 contains a seal 54 (Figs. 1 and 4). The seals 54 and the grooves 55 extend completely around the cylinder in the tangential and circumferential directions 58. The size of the seals 54 and grooves 55 is designed such that they are pre-tensioned in the axial direction 56 with a compressive force between the cylinder housing 8 and the sealing ring 46, and between the sealing ring 46 and the flange plate 43. The axial expansion of the seals 54 without pre-tension is therefore greater than with pre-tension and compression. The seal 54 between the flange plate 43 and the housing 45, as well as the seal 54 between the cylinder head 17 and the cylinder housing 8, is also pre-tensioned in the axial direction 56 with a compressive force. The components 8, 17, 42, 45, 46, 47, 49 of the piston compressor 1 are thus sealed against each other by the elastic seals 54.The compression chamber 29, the membrane interior 61, the membrane exterior 62, and the lubrication chamber 44 are thus sealed to the environment at the contact surfaces 51 between the components 8, 17, 42, 45, 46, 47, 49. The seals 54 are made, for example, of EPDM or silicone. Each seal 54 is arranged in only one groove 55. At least one connecting channel 102, preferably two connecting channels 102 as shown in Fig. 5, is formed in the flange plate 43 from the membrane interior 61 to the environment, so that the ambient pressure is essentially present in the membrane interior 61 to reduce the stress on the membrane 34, in contrast to the compressor system 65 shown in Fig. 6 with a throttle channel 84 and a drain channel 85 in the flange plate 43. The flange plate 43 thus has not only a mechanical function, but also hydraulic and / or pneumatic functions.The bellows 34 is indirectly and fluid-tightly attached at its upper axial end, facing the compression chamber 29, to a sealing ring 46 as a fastening element 47 at the lower end of the piston 5, i.e., the second piston part 5b (Figs. 1 and 3). The diaphragm 34 is fluid-tightly connected at its upper axial end to a lower end of the sealing ring 46 by the sealing element 42 as a fastening element 47. The sealing element 42 and the fastening element 47 between the sealing ring 46 as a fastening element 47 and the diaphragm 34 are formed by a material-bonded connection 52, in particular a welded joint 53 and / or an adhesive bond. The welded joint 53 is produced, for example, by laser welding. Similarly, an upper end of the sealing ring 46 is fixed to the lower end of the piston 5, i.e., the second piston part 5b.The sealant 42 and the fastener 47 between the sealing ring 46 and the piston 5 are formed by a material-bonded connection 52, in particular a welded connection 53 and / or an adhesive bond. The sealing ring 46 serves to seal and also indirectly fasten the diaphragm 34 to the piston 5 as a fastener 47.

[0077] The material-bonded connection 52 between the diaphragm 34 and the sealing ring 46 as a fastening element 47, and between the sealing ring 46 as a fastening element 47 and the second piston part 5b, is completely continuous in the circumferential direction 58 for a fluid-tight hermetic separation between a diaphragm interior 61 and a diaphragm exterior 62. The diaphragm 34 divides the cylinder compartment, bounded by the cylinder 6, the piston 5, and the flange plate 43, into the diaphragm interior 61 and the diaphragm exterior 62. A mixture of lubricating oil and air is present in the diaphragm interior 61 due to an incomplete seal between the lubrication chamber 44 and the diaphragm interior 61. The gas to be compressed is present in the diaphragm exterior 62 due to an incomplete seal at the gap seal between the piston 5 and the cylinder 6.The diaphragm interior 61 is fluid-tight and hermetically sealed from the diaphragm exterior 62 to prevent contamination of the gas to be compressed, particularly with lubricating oil, by means of oil carryover at the gap seal between the piston 5 with piston rings 16 and the cylinder 6 with piston guide 7. The upper sealing ring 46, acting as a fastening element 47, also forms a retaining ring 47 for fastening the diaphragm 34 to the piston 5. The sealing ring 46 has a sleeve-shaped or cylindrical extension 63 that extends into a recess on the second piston part 5b (Fig. 3). At the upper end of the piston rod 14, facing the piston 5, the piston rod 14 is designed with a small axial extension and a larger radial diameter, so that a stop ring 64 is formed on the piston rod 14. The stop ring 64 is preferably formed integrally with the rest of the piston rod 14.The axial end of the sleeve-shaped extension 63 of the fastening element 63, facing the compression chamber 29, rests on this circumferentially fully formed stop ring 64 58. This allows tensile forces from the piston rod 14 to be transmitted indirectly to the piston 5 via the fastening element 49 (the sealing ring 46) and the fastening element 47 in a form-fitting manner. Conversely, the axial end of the sleeve-shaped extension 63 exerts a compressive force on its underside, facing the lubrication chamber 44 at the axial end of the stop ring 64. Furthermore, the axial end of the piston rod 14 rests on the piston 5, i.e., the second piston part 5b, so that compressive forces can also be transmitted from the piston rod 14 to the piston 5, and vice versa, by transmitting a compressive force between the axial end of the piston rod 14 and the piston 5.The geometry of the piston rod 14 with stop ring 64 and the piston 5, i.e., the recess on the second piston part 5b, is designed such that a clearance or radial distance exists in the radial direction 57 between, on the one hand, the piston rod 14, in particular the stop ring 64, and, on the other hand, the piston 5 and the sealing ring 46. The piston 5 and the piston rod 14 are separate components. Thus, relative movement between the piston rod 14 and the piston 5 is possible in the radial direction 57. Therefore, no forces can be positively transmitted between the piston 5 and the piston rod 14 within this radial clearance or radial distance, in order to reduce the stress on the piston 5 from radial forces. This advantageously reduces the mechanical wear between the piston guide 7 on the cylinder 6 and the piston 5 with the piston rings 16.

[0078] In the radial direction 57, an optional guide ring 89 is formed between the second ring 60 of the lower sealing ring 46 and the piston rod 14. A guide bore 90 is formed in the flange plate 43, giving the flange plate 43 an annular shape. The piston rod 14 is supported in the guide bore 90 as a sliding bearing. Additionally, a cylindrical bearing sleeve 105 (Fig. 1) is formed on the underside of the flange plate 43, which is subjected to a compressive force due to the cylinder housing 8 and the housing 45, to increase the axial extent of the guide bore 90. The radial inner surface of the bearing sleeve 105 also forms the sliding bearing for the piston rod 14. The bearing sleeve 105 is arranged within the elastic element 28; preferably at least 50% or 90% of the axial extent of the bearing sleeve 105 is arranged within the elastic element 28.Similarly, a guide bore 90 is formed in the guide ring 89 as a sliding bearing for the piston rod 14. A friction-reducing and / or locally harder coating, e.g., a DLG coating as a diamond-like carbon coating, can be applied to the outside of the piston rod 14 and / or to the sliding bearing at one of the guide bores 90 to reduce friction and mechanical wear.

[0079] The axial extension of the piston rod 14 is significantly greater than the sum of the axial extensions of the at least one guide bore 90; preferably, the axial extension of the piston rod 14 is greater than two, three, or five times the sum of the axial extensions of the at least one guide bore 90, where the sum may also consist of only one term. The cylindrical guide bores 90 in the flange plate 43 and the guide ring 89 have only a small clearance or a radial distance of a few pm, for example, 0 to 50 pm, in the radial direction 57 between the radial outer surface of the piston rod 14 and the radial inner surfaces of the guide bores 90. The guide ring 89 can additionally be designed and function as a piston rod seal 89, for example, by being made of plastic instead of metal.This sliding bearing of the piston rod 14 on the guide bores 90 is lubricated with carried-over lubricating oil from the lubrication chamber 44 due to clearance or radial distance. The axial end regions of the guide bores 90 are conically shaped to avoid increased mechanical wear at a sharp edge. The guide bores 90 are also oriented substantially at a right angle to the disc-shaped flange plate 43, i.e., to an imaginary plane spanned by the disc-shaped flange plate 43, for example, with a deviation of less than 5°, 3°, or 1°. The guide bore 90 in the flange plate 43 serves to guide the piston rod 14.Due to the small clearance or radial distance between the piston rod 14 and the guide bore 90 in the flange plate 43, only a small leakage occurs from the lubrication chamber 44 into the diaphragm interior 61 and vice versa, so that the flange plate 43 also performs a sealing function between the diaphragm interior 61 and the lubrication chamber 44.

[0080] The cylinder head 17 is designed with a centering geometry 91 in the form of a centering projection 93 for alignment in the radial direction 57. The cylinder housing 8 is designed with a counter-centering geometry 92 in the form of a centering recess 94. A radial outer surface 91 of the centering projection 93 thus forms the convexly curved centering geometry 91. A radial inner surface 92 at the centering recess 94 forms the concavely curved counter-centering geometry 92. The centering geometry 91 and the counter-centering geometry 92 are essentially aligned parallel to each other and parallel to the longitudinal axis 41 of the cylinder 6 and the piston rod 14, in particular with a deviation of less than 5°, 3°, or 1°. The centering geometry 91 and the counter-centering geometry 92 are formed completely circumferentially in the tangential direction 58 or circumferential direction 58. The centering geometry 91 and the counter-centering geometry 92 have complete circumferential contact with each other, i.e.The centering geometry 91 rests on a contact surface on the counter-centering geometry 92. This centers the cylinder head 17 with respect to the cylinder 6 and the cylinder housing 8, and vice versa.

[0081] The cylinder housing 8 is centered with respect to the flange plate 43 by a centering geometry 91 and a counter-centering geometry 92, and vice versa, analogously as described above. For this purpose, an axial end region on the cylinder housing 8 forms a centering projection 93. A radial outer surface 92 of the centering projection 93 forms a counter-centering geometry 92. A large centering recess 94 is formed on the flange plate 43, such that a remaining circumferential ring, which delimits the centering recess 94, forms a centering geometry 91 on a radial inner surface 91. The housing 45 is centered with respect to the flange plate 43 by a centering geometry 91 and a counter-centering geometry 92, and vice versa, analogously as described above. For this purpose, an axial end region of the housing 45 forms a centering projection 93. A radial inner surface 91 of the centering projection 93 forms a centering geometry 91.A large centering recess 94 is formed on the flange plate 43, such that a remaining ring, which completely circumferentially or tangentially encircles the centering recess 94 and forms a counter-centering geometry 92 on a radial outer surface 92. The flange plate 43 thus indirectly serves to center the cylinder housing 8 relative to the housing 45 for the lubrication chamber 44 and the mechanism 40.

[0082] Additionally, a centering geometry 91 is formed on the cylinder housing 8 as a radial inner surface at a centering recess 93 (Fig. 5). A radial outer surface of the sealing ring 46 and the retaining ring 47 as a fastening element 49 forms a counter-centering geometry 92 for aligning the fastening element 49 in the radial direction 57 with respect to the cylinder housing 8.

[0083] Thus, centering geometries 91 and counter-centering geometries 92 are formed on components 8, 17, 42, 45, 46, 47, 49 for positive-locking centering as radial alignment of components 8, 17, 42, 45, 46, 47, 49 relative to each other. The term centering therefore means an alignment, in particular a radial alignment, of components 8, 17, 42, 45, 46, 47, 49 relative to each other. The centering geometry 91 and the counter-centering geometry 92 can also be formed by at least one centering pin and at least one counter-centering bore, in which at least one centering pin is arranged in at least one counter-centering bore (not shown).

[0084] The relevant axial extension 48 of the bellows 34 in the direction of the longitudinal axis 41, i.e., the area of ​​the diaphragm 34 which accommodates the stroke movements of the piston 5 between top and bottom dead center, is significantly greater than the stroke height of the piston 5, i.e., the difference between the top and bottom dead center of the piston 5. The extension 48 is, for example, 100 mm to 150 mm, and the stroke height of the piston 5 is preferably 10 mm, but at most 50 mm. In Fig. 1, the extension 48 and the stroke height of the piston 5 are not drawn to scale for illustrative purposes. This results in low mechanical stress on the deformation of the diaphragm 34, because a small axial deformation occurs per unit length of the bellows 34 extension 48. The membrane 34 can therefore be designed in this relevant area with the extension 48 not only as a bellows 34, but also as a simple membrane 34 without folding.Due to the minimal deformation of the diaphragm 34 in this relevant area with its dimension 48, the diaphragm 34 has a service life that is at least equivalent to the service life of the rest of the piston compressor 1. Because of the small stroke of the piston 5 and the large dimension 48 of the diaphragm 34, the axial expansion of the piston guide 7 is significantly smaller than the axial expansion of the cylinder housing 8. The diaphragm 34 is completely enclosed within the cylinder housing 8. For example, the axial extension of the piston guide 7 is less than 70%, 50%, 30%, or 10% of the axial extension of the cylinder housing 8. The piston rod 14 must be designed to be buckling-resistant, for example, by ensuring that the axial extension of the piston rod 14 is at least 5, 10, or 15 times greater than the diameter of the piston rod 14 outside the stop ring 64. The diameter of the piston rod 14 outside the stop ring 64 is, for example, less than 10 mm.9 mm or 8 mm. The piston 5 and the piston guide 7, for example, have a diameter between 10 mm and 50 mm, preferably between 20 mm and 40 mm.

[0085] The upper piston ring 16 is arranged in an upper annular groove 15 of the piston 5 (Figs. 3 and 4). For this purpose, a corresponding circumferential recess is formed in the first piston part 5a as a geometric feature of the first piston part 5a, so that after the first piston part 5a is fastened to the second piston part 5b with the pin 86, the upper annular groove 15 is formed on the piston 5. The upper piston ring 16 is a single piece and thus continuous in the circumferential direction 58. The upper piston ring 16 has a radial outer surface 109 and a radial inner surface 110 (Fig. 4). The radial outer surface 109 of the upper piston ring 16 also rests on the piston guide 7 and the cylinder 6 to seal the compression chamber 29. For the sealing of the compression chamber 29, it is necessary that the radial outer surface 109 of the piston ring 16 rests on the piston guide 7 and the cylinder 6 with a radial pressure force.In the radial direction 57, between the radial inner surface 110 of the upper piston ring 16 and a radial inner surface 113 of the piston 5, namely a radial inner surface 114 of the pin 86 of the first piston part 5a, a radial annular space 112, fully formed in the circumferential direction 58, is present. The radial annular space 112 has a substantially identical diameter in the radial direction 57, in particular with a deviation of less than 30%, 20% or 10%.

[0086] A piston ring channel 106 is formed in the piston 5, i.e., the first piston part 5a. The piston ring channel 106 is machined into the first piston part 5a by means of a drill. A first end 107 of the piston ring channel 106 opens into the compression chamber 29, and a second end 108 of the piston ring channel 106 opens into the radial annular space 112. Thus, the radial annular space 112 is gas-conducting and connected to the compression chamber 29; that is, the piston ring channel 106 forms a gas-conducting connection between the compression chamber 29 and the radial annular space 112 at the upper ring groove 15. The pressure of the gas to be compressed or of the compressed gas in the compression chamber 29 thus acts on the radial annular space 112 and exerts a radially outward force on the radial inner surface 110 of the upper piston ring 16.This radially outward-directed force causes the radial outer surface 109 of the upper piston ring 16 to bear against the piston guide 7 and the cylinder 6 with a compressive force. The upper piston ring 16 is essentially not mechanically preloaded, so the compressive force between the radial outer surface 109 of the piston ring 16 on the one hand and the cylinder 6 and the piston guide 7 on the other hand is essentially entirely caused by the compressive force of the gas in the radial annular space 112 acting on the radial inner surface 110 of the upper piston ring 16. Due to the translational movement between the piston ring 16 and the radial outer surface 109 of the piston ring 16, small plastic deformations 111 occur, which are shown as dashed lines in Fig. 4.However, since the pressure of the gas in the compression chamber 29 is exerted on the radial annular space 112 through the piston ring channel 106, this plastic deformation 111 does not cause any change in the pressure force between the radial outer surface 109 of the piston ring 16 and the cylinder 6 and the piston guide 7. In the axial direction 56, there is essentially no clearance between the upper piston ring 16 and the piston 5, i.e., between the first piston part 5a and the second piston part 5b and the upper piston ring 16, and due to this very small clearance, an axial annular space 115 in the axial direction 56 between the piston 5 and the piston ring 16 is not shown in Fig. 4.As an additional volume of the dead space of the compression chamber 29, the volume of the radial annular space 112 and the piston ring channel 106 is thus advantageously only the volume of the radial annular space 112 and the piston ring channel 106, because the volume of the axial annular space 115 can be neglected as a gap seal.

[0087] In another embodiment, not shown, the second end 108 of the piston ring channel 106 does not open into the radial annular space 112, but into the axial annular space 115. The axial clearance between the upper piston ring 16 and the first piston part 5a is greater in the radial direction 57 from the second end 108 to the radial annular space 112 than outside this flow direction. A circumferential step 58 is formed on the upper axial end of the upper piston ring 16 facing the compression chamber 29, so that the upper axial end of the upper piston ring 16 rests on the first piston part 5a only between the step and the radial outer surface 109 of the upper piston ring 16 in the radial direction 57, thus forming the gap seal.

[0088] Figure 7 shows a compressor system 65 with the piston compressor 1 described above. In the embodiment shown in Figure 7, the compressor system 66 has only one piston compressor 1, but it can also be configured with several piston compressors 1 and / or with one piston compressor 1 with several cylinders 6 and several pistons 5. The piston compressor 1 in Figure 7 is shown in a highly simplified and schematic form. The compressor system 66 comprises a container 66 with gas to be compressed, a container 67 with the compressed gas, and a lubricating oil reservoir 81. The gas to be compressed is supplied to the piston compressor 1 via a suction line 68, and the compressed gas is supplied to the container 67 via a pressure line 69.The diaphragm outer chamber 62 is fluidly connected to the suction line 68 via a leakage return line 70, and thus also fluidly connected to the inlet valve 19 and the inlet port 22 of the piston compressor 1, as well as fluidly connected to the reservoir 66. The leakage return line 70 is connected to the diaphragm outer chamber 62 via a leakage bore 103 (Fig. 6) in the cylinder housing 8. The gap seal between the piston guide 7 on the cylinder 6 and the piston 5 with the piston rings 16 is not completely sealed, so that the gas to be compressed enters the diaphragm outer chamber 62, and this leakage of the gas to be compressed is fed back into the suction line 68, i.e., reused and not discharged unused into the environment. A throttle 71, acting as a constriction, limits the volume flow of leakage gas through the leakage return line 70. A pressure sensor 74 monitors the pressure in the membrane outer space 62.A pressure sensor 72 monitors the pressure in the suction line 68. A pressure sensor 73 monitors the pressure in the pressure line 69. A shut-off device 75, in particular a valve 75, can reduce or completely close off the flow of the gas to be compressed from the container 66 to the piston compressor 1. A shut-off device 76, in particular a valve 76, in the pressure line 69 can reduce or completely close off the flow of the compressed gas from the piston compressor 1 to the container 67.

[0089] The lubrication chamber 44 of the piston compressor 1 is sealed from the environment, and lubricating oil in the lubricating oil reservoir 81 is pumped from the lubricating oil reservoir 81 to the lubrication chamber 44 by a pumping device 79, in particular a gear pump 80, through a lubricating oil line 77. A throttle channel 84 with a small flow cross-sectional area extends from the lubrication chamber 44 into the diaphragm interior 61. A drain channel 85 with a significantly larger flow cross-sectional area than that of the throttle channel 84 extends from the diaphragm interior 61 to a lubricating oil line 78. The flow cross-sectional area of ​​the drain channel 85 is, for example, at least 2, 3, or 5 times larger than the flow cross-sectional area of ​​the throttle channel 84.The lubricating oil, which is directed from the lubrication chamber 44 into the diaphragm chamber 61 via the throttle channel 84, is returned to the lubricating oil reservoir 81 through the drain channel 85 and the lubricating oil line 78. This creates a lubricating oil circuit that not only lubricates the mechanism 40 in the lubrication chamber 44 but also cools it and additionally lubricates the diaphragm chamber 61. Because the lubricating oil is routed outside the piston compressor 1, heat can also be dissipated from the lubricating oil to the environment, for example, via the lubricating oil lines 77, 78, and the lubricating oil reservoir 81. Optionally, an additional heat exchanger, preferably with an ambient air blower, can be installed or integrated into the lubricating oil circuit as an oil cooler (not shown). The pressure in the lubricating oil chamber 44 is higher than the ambient pressure, for example, a pressure between 2 and 5 bar.The lubricating oil reservoir 81 is essentially at ambient pressure of 1 bar due to a vent valve 83, which connects the lubricating oil reservoir 81 to the environment. As a safety measure, a pressure sensor 82 monitors the pressure in the lubricating oil reservoir 81. The pressure sensors 72, 73, 74, and 82 are connected to a control and / or regulation unit (not shown) via data lines (not shown). The control and / or regulation unit detects the pressures detected by the pressure sensors 72, 73, 74, and / or 82 and, depending on the detected pressures, can trigger an error message and / or shut down the compressor system 65. The pressure sensors 72, 73, 74, and / or 82 may also include a display device for the optical indication of the pressure. The optical pressure indicator allows a user of the compressor system 65 to manually monitor the correct pressure.The lubrication chamber 44 and the membrane interior 61 are thus lubricated and cooled by a lubrication system 104 of the compressor system 65.

[0090] The compressor system 65 comprises a base frame 95 or a base element 95, preferably made of metal, for fixing the essential components of the compressor system 65. The base frame 95 or the base element 95 rests on the floor or substrate. The container 66 with the gas to be compressed, the container 67 with the compressed gas under high pressure, the lubricating oil reservoir 81, and the piston compressor 1 are attached to the base frame 95 or base element 95. The essential components 1, 66, 67, and 81 are each fixed to the common base frame 95 by separate retaining elements 96. The retaining elements 96 are integral parts of the base frame 95.

[0091] In the two-piston compressor 1 shown in Fig. 6, with two pistons 5 and two cylinder housings 8, a mounting bracket 97 is fixed to each cylinder housing 8. A connecting bore 99 (not shown) is formed at each end of the mounting bracket 97. The two mounting brackets 97 are connected to each other by a connecting piece 98. A connecting bore 99 (not shown) is formed at each end of the connecting piece 98, and these connecting bores 99 are aligned with the connecting bores 99 on the mounting brackets 97. A connecting element 100, in the form of a screw 101 or a rivet, is arranged in each of these aligned connecting bores 99. The two cylinder housings 8 are thus positively and preferably frictionally connected to each other. The housing 45 for the two pistons 5 and two cylinder housings 8 is as shown in Fig.The connecting piece 6 is attached to the base frame 95 by means of the retaining element 96. Additionally, the connecting piece 98 has a central connecting bore 99, and a further connecting piece 98 (not shown) is attached to the base frame 95 or bottom element 95 via this connecting bore 99. The mechanical stresses and the forces to be transmitted on the cylinder housing 8, the flange plate 43, and the housing 45 can be reduced because the connecting piece 98 firmly connects the two cylinder housings 8 to each other, thus increasing stiffness. Furthermore, the connecting piece 98 (not shown) is fixed to the base frame 95 or bottom element 95 by means of the connecting piece 98 shown in Fig. 6. Thus, at least one cylinder housing 8 is attached to the base frame 95 with at least one connecting piece 98.

[0092] Overall, the piston compressor 1 and the compressor system 65 according to the invention offer significant advantages. The diaphragm 34, acting as a bellows 34, enables the complete hermetic separation of the lubrication chamber 44 containing the lubricant from the compression chamber 29. The piston compressor 1 can thus compress gases, such as hydrogen or oxygen, with high purity requirements. The additional costs for manufacturing the diaphragm 34 in the piston compressor 1 are low, making the piston compressor 1 advantageously inexpensive to produce and requiring little installation space. The two-part piston 5, comprising the first piston part 5a and the second piston part 5b, can advantageously be optimized with respect to its geometry and / or material.

[0093] The piston ring channel 106 from the compression chamber 29 into the radial annular space 112 enables reliable pressure of the gas in the compression chamber 29 to be applied to the radial annular space 112. Even plastic deformation 111 of the piston ring 16 does not reduce the pressure of the gas in the annular space 112. Furthermore, the piston compressor 1 advantageously has a small dead space volume because only the piston ring channel 106 and the radial annular space 112 increase the dead space volume, in addition to the dead space volume of the compression chamber 29 at the top dead center of the piston 5. Due to a negligible axial clearance 56 between the piston ring 16 and the piston 5, an axial annular space 115 between the piston ring 16 and the piston 5 can be neglected for determining the dead space volume.

Claims

Claims 1. Piston compressor (1) for compressing gases, comprising at least one cylinder (6), at least one piston (5) which is mounted in each cylinder (6), such that each piston (5) and each cylinder (6) define a compression chamber (29) for compressing the gas, an inlet valve (19) for each compression chamber (29), an outlet valve (20) for each compression chamber (29), at least one annular groove (15) formed in the piston (5), at least one piston ring (16) and in each annular groove (15) each piston ring (16) is arranged and on a radial inner surface (110) of each piston ring (16) each a radial annular space (112) is formed for applying a radially outwardly directed pressure force by means of the gas in the compression chamber (29) with a gas-conducting connection between the compression chamber (29) and each radial annular space (112),to achieve a seal of the compression chamber (29) between a radial outer surface (109) of each piston ring (16) and each cylinder (6) by means of the radially outwardly directed pressure force applied to the radial inner surface (110) of each piston ring (16), characterized in that at least one piston ring channel (106) is formed in each piston (5) as a gas-conducting connection from the compression chamber (29) to the at least one radial annular space (112), so that the pressure of the gas to be compressed in the compression chamber (29) acts through the at least one piston ring channel (106) on the radial outer surface (109) of each piston ring (16).

2. Piston compressor according to claim 1 , characterized in that the at least one piston ring channel (106) is oriented substantially in one direction parallel to a longitudinal axis (41) of the cylinder (6).

3. Piston compressor according to claim 1 or 2, characterized in that the at least one piston ring channel (106) is, in particular exclusively, straight.

4. Piston compressor according to one or more of the preceding claims, characterized in that the flow cross-sectional area of ​​the at least one piston ring channel (106) is essentially identical.

5. Piston compressor according to one or more of the preceding claims, characterized in that the axial clearance, in particular as the extension of an axial annular space (115) between the piston ring (16) and the piston (5) in the axial direction (56), between each piston ring (16) and the piston (5) at a temperature of 20°C is less than 500 pm, 300 pm, 200 pm, 100 pm, 50 pm, 10 pm or 5 pm.

6. Piston compressor according to one or more of the preceding claims, characterized in that each piston (5) is formed in two parts with a first piston part (5a) and a second piston part (5b).

7. Piston compressor according to one or more of the preceding claims, characterized in that a ring groove (15) is formed between the first and second piston part (5a, 5b) due to the geometry of the first and second piston part (5a, 5b) and a piston ring (16) is arranged in the ring groove (15).

8. Piston compressor according to one or more of the preceding claims, characterized in that the piston compressor (1) comprises at least one mechanism (40) with which the at least one piston (5) is in mechanical operative connection for an oscillating movement of the at least one piston (5).

9. Piston compressor according to claim 8, characterized in that the piston compressor (1) comprises at least one lubrication chamber (44) in which the at least one mechanism (40) is at least partially arranged and the at least one mechanism (40) in the at least one lubrication chamber (44) can be lubricated with a lubricant.

10. Piston compressor according to claim 9, characterized in that the piston compressor (1) comprises at least one diaphragm (34) and with the at least one diaphragm (34) each a lubrication chamber (44) of one Compression space (29) is separated.

11. Piston compressor according to claim 10, characterized in that the at least one diaphragm (34) is designed as at least one bellows (34).

12. Piston compressor according to claim 10 or 11, characterized in that each diaphragm (34) divides the cylinder partial space bounded by each cylinder (6), each piston (5) and preferably each flange plate (43), in particular in the radial direction (57), into a diaphragm inner space (61) and diaphragm outer space (62).

13. Piston compressor according to one or more of the preceding claims, characterized in that the stroke height of each piston (5) between the top and bottom dead center of the piston (5) is less than 30%, 10%, 5% or 3% of the extension (48) relevant for the stroke movement of the at least one diaphragm (34), in particular of the at least one bellows (34), in the direction of a longitudinal axis (41) of the cylinder (6).

14. Piston compressor system (65) for compressing gases, comprising a piston compressor (1) with at least one piston (5) and with at least one mechanism (40) with which the at least one piston (40) is in mechanical operative connection for an oscillating movement of the at least one piston (5), a lubrication system (104) with at least one lubricating oil line (77, 78), a lubricating oil reservoir (81) and a conveying device (79, 80) for Lubricating oil for lubricating the at least one mechanism (40) arranged in a lubrication chamber (44), a drive motor for the piston compressor (1), a container (66) with the gas to be compressed, a container (67) with the compressed gas, characterized in that the piston compressor (1) is designed according to one or more of the preceding claims.

15. Piston compressor system according to claim 14, characterized in that a throttle channel (84) is formed from the lubrication chamber (44) into the diaphragm interior (61) for directing lubricating oil into the diaphragm interior (61) and a drain channel (85) is formed from the diaphragm interior (61) into the lubricating oil line (78) for directing lubricating oil from the diaphragm interior (61) into the lubricating oil line (78) and / or into the lubricating oil reservoir (81).

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