Piston compressor

Abstract

This invention relates to a piston compressor (1) for compressing gas, comprising a piston (5), a cylinder chamber (49) divided by the piston (5) into a first cylinder portion chamber (50) and a second cylinder portion chamber (51) serving as a compression chamber (29) for compressing gas, a mechanical device (40) to which the piston (5) is mechanically connected for reciprocating motion of the piston (5), a lubrication chamber (44) in which the mechanical device (40) is at least partially disposed, and which is lubricated in the lubrication chamber (44) by means of a lubricant, and a diaphragm (34) connecting the lubrication chamber (44) to the compression chamber (29). 29) The fluid is fluid-tightly separated, and a diaphragm (34) arranged in the second cylinder partial chamber (51) divides the second cylinder partial chamber (51) into a diaphragm inner space (52) and a diaphragm outer space (53), wherein the reciprocating compressor (1) includes a pressure balancing device (54) having channels (55, 56, 57) for introducing and / or exporting balancing fluid into and / or exporting balancing fluid into the diaphragm inner space (52) according to the pressure in the diaphragm outer space (53), and / or conversely, for introducing and / or exporting balancing fluid into and / or exporting diaphragm outer space (53) according to the pressure in the diaphragm inner space (52) so as to achieve substantially the same pressure in the diaphragm inner space (52) and the diaphragm outer space (53).

Description

Technical Field

[0001] The present invention relates to a reciprocating compressor according to the preamble of claim 1 and a method for operating the reciprocating compressor according to the preamble of claim 12. Background Technology

[0002] Piston compressors are used in various technical applications to compress gases. In a piston compressor, a piston performs a reciprocating motion. The piston is supported in a cylinder. An inlet valve is used to introduce gas into the compression chamber, and an outlet valve is used to discharge gas from the compression chamber. The compression chamber is defined by the surface of the cylinder head at the end opposite the piston. The inlet and outlet valves are usually integrated into the cylinder head. The reciprocating motion of the piston is achieved by a mechanical device. This mechanical device is constructed, for example, as a crank-driven mechanism with a crankshaft and connecting rod, or as a roller shoe with working rollers and a drive shaft with at least one cam. This mechanical device is arranged in a lubrication chamber. The lubrication chamber is loaded with a lubricant, such as lubricating oil, to lubricate the moving parts of the mechanical device. This mechanical device is driven, for example, by an electric motor. The piston performs a reciprocating motion between the top dead center (TDC) and bottom dead center (BDC) of the piston, and the volume difference of the compression chamber between the TDC and BDC defines the stroke volume. The clearance volume (Totvolumen) of the compression chamber is the volume of the compression chamber at the top dead center of the piston.

[0003] Certain technical applications involving compressed gases require the supply of compressed gases with high purity. The seal between the cylinder and the piston with piston rings is not a complete gap seal, allowing lubricant to enter the compression chamber of the reciprocating compressor from the lubrication chamber, thus contaminating the compressed gas. To prevent this undesirable and unavoidable contamination of the compressed gas, it is known to create an additional space between the compression chamber and / or the space with the piston and the lubrication chamber, and to provide, for example, a suction device for this space. However, this is disadvantageously very complex, resulting in high manufacturing costs and large structural space for the reciprocating compressor. Furthermore, diaphragm compressors are also known, but these have a small delivery volume per unit volume of structural space.

[0004] EP 0 541 482 B1 illustrates a reciprocating compressor for oil-free gas compression, having at least one cylinder and a piston guided therein, the piston having at least one slit, so-called trapping piston ring disposed in an annular groove on the piston, the piston ring defining a pressure-loaded space of the annular groove in the compression chamber by its outer peripheral surface opposite to the inner surface of the cylinder, and from the outer peripheral surface having two radially parallel limiting interfaces, wherein the face facing the compression chamber extends over a portion of the radial ring width, wherein the piston ring is slidably guided by its two parallel limiting interfaces on corresponding faces of the annular groove, wherein the remaining face of the piston ring facing the compression chamber, originating from the outer peripheral surface facing the inner surface of the cylinder, is configured as a wedge-shaped face, the wedge-shaped face extending to the limiting interface at an angle of 5° to 15° to a line parallel to the limiting interface facing the compression chamber.

[0005] DE 2020699 A1 discloses an immersion piston compressor having a single-stage or multi-stage piston and / or cylinder, wherein at least one bellows is arranged as a diaphragm between each piston and the crankcase. The bellows divides the cylinder chamber, which serves as the space below the piston, into a wet chamber, which serves as the inner space of the diaphragm, and a dry chamber, which serves as the outer space of the diaphragm. Summary of the Invention

[0006] A reciprocating compressor for compressing gas according to the present invention includes a cylinder, a piston supported in the cylinder, a cylinder chamber divided by the piston into a first cylinder portion chamber and a second cylinder portion chamber serving as compression chambers for compressing gas, an inlet valve for the compression chamber, an outlet valve for the compression chamber, a mechanical device mechanically connected to the piston for reciprocating motion of the piston, a lubrication chamber in which the mechanical device is at least partially arranged and can be lubricated with a lubricant, and a diaphragm connecting the lubrication chamber to the gas cavity. The compression chambers are fluid-sealed and separated, and a diaphragm arranged in the second cylinder portion of the chamber divides the second cylinder portion into an internal diaphragm space and an external diaphragm space. The reciprocating compressor includes a pressure balancing device having channels for introducing and / or draining balancing fluid from the internal diaphragm space according to the pressure in the external diaphragm space, and / or conversely, for introducing and / or draining balancing fluid from the external diaphragm space according to the pressure in the internal diaphragm space, so as to achieve substantially the same pressure in the internal and external diaphragm spaces. In another variation, the second cylinder portion is the space between the piston and the mechanical and / or lubrication chambers, such that the second cylinder portion is preferably partially confined by the cylinder. Preferably, the second cylinder portion is at least partially confined by the cylinder.

[0007] In a supplementary embodiment, the reciprocating compressor includes a connecting channel, and the diaphragm external space is fluidly connected via this connecting channel to the inlet channel of the inlet valve, particularly to the supply container of the gas to be compressed, so as to equalize the pressure of the fluid in the diaphragm external space with the pressure in the inlet channel of the inlet valve. Due to this fluid connection between the diaphragm external space and the inlet channel of the inlet valve, during operation, there are substantially the same pressure in the diaphragm external space and the inlet channel of the inlet valve, particularly with a deviation of less than 30%, 20%, or 10%. Volume changes in the diaphragm external space due to piston movement can also be balanced by introducing and / or draining the gas to be compressed into and / or from the diaphragm external space. The presence of the gas to be compressed in the diaphragm external space substantially, particularly at least 80%, 90%, or 95% (as a volume percentage and / or mass percentage) ensures that even if there is a leak between the piston and the piston guide at the piston rings, no material that could contaminate the gas to be compressed will reach the compression chamber from the diaphragm external space. When the space outside the diaphragm is filled with ambient air, the gas to be compressed (e.g., hydrogen) may be harmfully contaminated by the ambient air and thus become unusable.

[0008] In another variation, the diaphragm interior space is provided with a first channel for introducing balancing fluid into the diaphragm interior space and a second channel for introducing balancing fluid into and / or exporting balancing fluid from the diaphragm interior space.

[0009] In an additional configuration, the reciprocating compressor includes a delivery device by means of which the compressor, in particular, can introduce a balancing fluid, in particular air, into the internal space of the diaphragm through a first channel.

[0010] In a supplementary variant, during the operation of the reciprocating compressor, the balancing fluid can be continuously introduced into the diaphragm interior space via a first channel using a conveying device.

[0011] Preferably, the reciprocating compressor includes an intermediate container, and a second passage leads into the intermediate container.

[0012] In an additional embodiment, a second channel can be used to guide balancing fluid and preferred lubricant.

[0013] In another embodiment, excess balancing fluid introduced into the diaphragm interior space can be exported from the diaphragm interior space through a second channel and introduced into an intermediate container.

[0014] In a supplementary variant, the reciprocating compressor includes an actuator by means of which a balancing fluid in an intermediate container can be discharged based on the pressure in the external space of the diaphragm, so as to achieve substantially the same pressure, particularly with a deviation of less than 30%, 20%, or 10%, in the intermediate container and the external space of the diaphragm during operation. Therefore, the volumetric flow of the balancing fluid and, optionally, lubricant discharged from the intermediate container by means of the actuator is controlled and / or regulated based on the pressure in the external space of the diaphragm and / or the inlet passage of the connecting channel and / or the inlet valve and / or the supply container serving as a storage container for the gas to be compressed, so as to achieve substantially the same pressure in the intermediate container and the external space of the diaphragm, such that substantially the same pressure exists in the internal space of the diaphragm and the external space of the diaphragm due to the connection of the guiding fluid between the intermediate container and the internal space of the diaphragm.

[0015] In particular, the actuator is a valve, especially a servo valve, which is fluidly connected via a control channel to the inlet channel of an inlet valve, especially to a supply container for the gas to be compressed, so as to control the actuator by means of the pressure of the gas to be compressed in the inlet channel of the inlet valve. Preferably, the actuator is controlled by changing the flow cross-section for balancing fluid and / or lubricant, especially by means of controlling the movement of a piston.

[0016] In another embodiment, the reciprocating compressor includes a discharge passage and a collection container, and fluid, particularly balancing fluid and / or lubricant, discharged from the actuator can be introduced into the collection container through the discharge passage.

[0017] A method for operating a reciprocating compressor for compressing gas according to the present invention includes the following steps: a cylinder chamber is divided by a piston into a first cylinder portion chamber and a second cylinder portion chamber, which serve as compression chambers for compressing gas; a gas to be compressed is introduced into the compression chamber through an inlet valve; the gas introduced into the compression chamber is compressed by means of a piston, wherein the piston performs a stroke motion to reduce the volume of the compression chamber; the gas compressed in the compression chamber is discharged from the compression chamber through an outlet valve; the reciprocating motion of the piston is performed by means of a mechanical device mechanically connected to the piston; and the mechanical device is lubricated by means of a lubricant in a lubrication chamber. The mechanical device is at least partially arranged in the lubrication chamber; the lubrication chamber and the compression chamber are fluidly and sealingly separated by a diaphragm, and the second cylinder partial chamber is divided by the diaphragm into an inner space and an outer space, wherein a balancing fluid is introduced into and / or discharged from the inner space of the diaphragm according to the pressure of the fluid in the outer space of the diaphragm, and / or conversely, a balancing fluid is introduced into and / or discharged from the outer space of the diaphragm according to the pressure of the fluid in the inner space of the diaphragm, so as to achieve substantially the same pressure in the inner space and the outer space of the diaphragm, wherein the balancing fluid is preferably conveyed by means of a conveying device.

[0018] In another variation, the balancing fluid is introduced, particularly continuously and / or persistently, into the internal space of the diaphragm through a first channel for introducing the balancing fluid, and excess fluid introduced into the internal space of the diaphragm through the first channel is discharged from the internal space of the diaphragm through a second channel, particularly continuously and / or persistently.

[0019] In a supplementary embodiment, the volumetric flow of fluid, guided through the second channel and acting as a balancing fluid and / or lubricant, is controlled and / or regulated such that substantially the same pressure, particularly with a deviation of less than 30%, 20%, or 10%, exists in the internal and external spaces of the diaphragm. The fluid guided through the second channel is introduced into and / or discharged from the internal space of the diaphragm.

[0020] Preferably, the outer space of the diaphragm is fluidly connected to the inlet channel of the inlet valve, particularly the supply container of the gas to be compressed, via a connecting channel, such that the pressure of the fluid in the outer space of the diaphragm substantially corresponds to the pressure in the inlet channel of the inlet valve, particularly with a deviation of less than 30%, 20%, or 10%, by means of introducing the gas to be compressed into the outer space of the diaphragm through the connecting channel and / or exporting it from the outer space of the diaphragm.

[0021] In a supplementary variation, the volumetric flow of the balance fluid and / or lubricant guided through the second channel is controlled and / or regulated by controlling and / or regulating the pressure of the balance fluid and / or lubricant in the intermediate container.

[0022] In a supplementary variation, the pressure of the balancing fluid and / or lubricant in the intermediate container is controlled and / or regulated by means of an actuator, particularly a servo valve, based on the pressure in the inlet channel of the inlet valve and / or the pressure in the external space of the diaphragm and / or the pressure of the gas to be compressed in the supply container, thereby controlling and / or regulating the volumetric flow of the balancing fluid and / or lubricant discharged from the intermediate container, such that the pressure in the internal space of the diaphragm substantially corresponds to the pressure in the external space of the diaphragm.

[0023] To meet the destination, the volumetric flow of balancing fluid and / or lubricant discharged from the intermediate container is controlled and / or regulated by controlling and / or adjusting the flow cross-section in the actuator for balancing fluid and / or lubricant.

[0024] Preferably, the actuator is fluidly connected to the inlet channel of the inlet valve, particularly the supply container of the gas to be compressed, via a control channel.

[0025] Preferably, the external space of the diaphragm has no connection to the ambient air to guide fluid. Therefore, the external space of the diaphragm is sealed relative to the surrounding environment.

[0026] In an additional configuration, the internal space of the diaphragm is constructed within the diaphragm in the radial direction, and the external space of the diaphragm is constructed outside the diaphragm.

[0027] In another embodiment, the number of corrugations in the bellows is greater than 5, 10, 30, 50, 100, or 200.

[0028] In an additional embodiment, the method described in this patent application is performed using a piston compressor described in this patent application.

[0029] In a supplementary variation, the method described in this patent application can be performed using a piston compressor described in this patent application.

[0030] In another variation, the mechanical device, particularly the piston rod, is at least partially arranged within the space inside the diaphragm.

[0031] Preferably, the internal space of the diaphragm is fluidly connected to the lubrication chamber.

[0032] The diaphragm is constructed as a bellows, which is appropriate for the destination.

[0033] In an additional variation, the diaphragm, particularly the bellows, is indirectly and / or directly fixed to the remainder of the reciprocating compressor in a fluid-tight manner via at least one sealing device and / or fastening device, particularly at least one material-locking connection and / or at least one clamping connection and / or at least one sealing ring and / or at least one fastening ring, to prevent lubricant from entering the at least one compression chamber from the lubrication chamber. Preferably, the remainder of the compressor is formed by a cylinder housing and / or cylinder head and / or a housing for the mechanical device and / or flange plates and / or a piston. Preferably, the sealing ring is made of metal and / or plastic. The sealing ring, made of metal and plastic, is fixed to the remainder of the reciprocating compressor, preferably the piston, made of metal, for example, by welding, and the other side of the sealing ring, made of plastic, is fixed to the diaphragm made of plastic by welding.

[0034] In another variation, the at least one sealing device and / or the at least one fastening device, particularly the at least one sealing ring and / or the at least one fastening ring and / or the at least one material locking connection, are fully constructed in the circumferential direction.

[0035] Preferably, the internal space of the diaphragm is sealed relative to the external space of the diaphragm, in particular by means of a diaphragm fluid seal, so that no balancing fluid and optional lubricant can be guided from the internal space of the diaphragm to the external space of the diaphragm.

[0036] In another variation, the second cylinder portion chamber is divided by a diaphragm, particularly by the diaphragm only, in a radial direction relative to the longitudinal axis of the cylinder into an inner space and an outer space.

[0037] In a supplementary configuration, the diaphragm, and especially the bellows, is arranged at least partially, and especially completely, between the piston and the mechanism in the longitudinal direction of the cylinder.

[0038] In another embodiment, the diaphragm, especially the bellows, is constructed in a substantially cylindrical shell shape, particularly in the region inside the at least one cylinder.

[0039] In a supplementary variation, the piston is mechanically connected to the mechanical device via a piston rod.

[0040] To suit the destination, a flange is arranged between the cylinder and the mechanical device along the longitudinal axis of the cylinder.

[0041] In an additional configuration, the diaphragm, particularly the bellows material, is secured, in particular by means of at least one welded connection, as a sealing and / or fastening device, either directly or indirectly.

[0042] Preferably, the piston's stroke height between its top dead center and bottom dead center is less than 30%, 10%, 5%, or 3% of the extension of the diaphragm, and especially the bellows, in the longitudinal axis direction of the cylinder related to the stroke movement. Thus, the mechanical load on the diaphragm in the extension related to the stroke movement is small during the piston's reciprocating motion, resulting in a long service life for the at least one diaphragm.

[0043] In an additional variation, the clearance volume (Totvolumen) of the compression chamber is less than 10%, 5%, 3%, or 2% of the stroke volume of the compression chamber. Advantageously, the reciprocating compressor can thus achieve high pressure of the gas to be compressed at a small piston stroke height by means of a shaft having at least one cam and a mechanical device including working rollers.

[0044] The cylinder, including the cylinder head, is suitable for the destination.

[0045] In an additional embodiment, the working roller comprises a cylindrical shell-shaped working roller with a central bore, in which a bearing pin is arranged. An annular gap is formed between the cylindrical shell-shaped working roller and the bearing pin, and this annular gap is lubricated with a lubricant. The axial end of the bearing pin is supported in a roller shoe, for example, by a sliding bearing.

[0046] In a supplementary variation, the material locking connection is constructed as a welded connection and / or an adhesive connection.

[0047] Preferably, the at least one welded joint is manufactured by laser welding. Welded joints manufactured by laser welding can be easily distinguished from welded joints manufactured by other methods due to the characteristics of the structural design, such as the diameter of the weld and / or the geometry of the weld on the welded components.

[0048] In an additional embodiment, the surface extension dimension of the diaphragm is greater than 5, 10, 20, or 30 times the diaphragm thickness. Therefore, the surface extension dimension of the diaphragm is significantly greater than the diaphragm thickness.

[0049] In an additional embodiment, the diaphragm is made of metal and / or plastic. Preferably, the plastic construction of the diaphragm is an elastomer. The diaphragm is flexible to withstand the reciprocating motion of the piston. Preferably, the diaphragm consists of multiple layers, particularly layers made of different materials such as metal and / or plastic. A layer, for example a thin layer made of metal such as aluminum foil, reduces the permeation of substances through the diaphragm. The diaphragm has a very small permeability coefficient, especially for lubricants. Q = P * F * t * Δp / d, where Q is the amount of gas or vapor passing through a layer of area F and thickness d in time t, when the pressure difference of the permeate before and after the layer is Δp. The oxygen permeability of the diaphragm (in cm⁻¹) 3 / m 2 The hydrogen permeability of the membrane (in *d*bar) is preferably less than 30, 10, 1, or 0.1. 3 / m 2 (Using *d*bar as the unit) preferably less than 50, 10, 1 or 0.2.

[0050] In another embodiment, the cylinder has a longitudinal axis. The longitudinal axis of the cylinder corresponds to the direction of movement of the piston supported in the cylinder.

[0051] In another embodiment, the mechanical device includes a shaft having at least one cam, and the at least one piston is indirectly supported on the shaft having at least one cam by roller shoes and working rollers. As desired, the shaft having at least one cam is an eccentric shaft.

[0052] In another embodiment, the mechanical device consists of a crankshaft and a connecting rod that serves as a piston rod.

[0053] In an additional variant, the reciprocating compressor includes an electric motor for driving the reciprocating compressor. For example, the electric motor drives a drive shaft with cams and / or a crankshaft.

[0054] The pressure that can be generated by a reciprocating compressor is in the range of 100 bar to 1000 bar. Attached Figure Description

[0055] Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. The drawings show: Figure 1 Cross-section of a reciprocating compressor used for compressing gases. Figure 2 According to the working rollers and drive shaft with roller shoes Figure 1 AA section; and Figure 3 The cross-section of the reciprocating compressor for compressing gas in the second embodiment. Figure 4 According to Figure 3 The second embodiment is a highly simplified cross-section of a similar reciprocating compressor, which has a pressure balancing device. Detailed Implementation

[0056] exist Figure 1 The diagram shows a cross-section of a reciprocating compressor 1 for compressing gas according to a first embodiment. The reciprocating compressor 1 is used to compress gas, such as hydrogen or air, under high pressure. The pressure that the reciprocating compressor 1 can generate is, for example, between 100 bar and 1000 bar.

[0057] The reciprocating compressor 1 includes a drive shaft 2 with two cams 3, which rotates about a rotation axis 26. The drive shaft 2 is driven by an electric motor (not shown). The rotation axis 26 is located at... Figure 1 Within the drawing plane and perpendicular to Figure 2 The drawing plane. Piston 5 is supported in cylinder 6 on piston guide 7 formed by cylinder housing 8. A completely circumferential annular groove 15 is constructed on the radially outer side of piston 5. A piston ring 16 is arranged in the annular groove 15. Compression chamber 29 is limited by cylinder housing 8, cylinder head 17 and piston 5. End 18 of cylinder head 17 is the surface part of cylinder head 17 that limits compression chamber 29 and does not function as part of cylinder 6. Inlet passage 22 with inlet valve 19 and outlet passage 24 with outlet valve 20 lead to compression chamber 29. Gas flows into compression chamber 29 through inlet passage 22 with inlet opening 21, and gas under high pressure flows out of compression chamber 29 through outlet passage 24 with outlet opening 23. Inlet valve 19, for example check valve, is configured such that only gas flows into compression chamber 29, and outlet valve 20, for example check valve, is configured such that only gas flows out of compression chamber 29. The volume of the compression chamber 29 changes due to the reciprocating stroke of the piston 5. The piston 5 is indirectly supported on the drive shaft 2 by means of the piston rod 14. A roller shoe 9 with working rollers 10 is fixed to the end of the piston rod 14. The working rollers 10 can rotate here, and their axis of rotation 25 is located at... Figure 1 The drawing plane shown is in and perpendicular to Figure 2 The drawing plane. The drive shaft 2 having at least one cam 3 has a shaft-rolling surface 4, and the working roller 10 has a roller-rolling surface 11.

[0058] The roller-rolling surface 11 of the working roller 10 rolls at the contact surface 12 on the shaft-rolling surface 4 of the drive shaft 2, which has two cams 3. The roller shoe 9 is supported in a roller shoe bearing formed by the cylinder housing 8, which acts as a sliding bearing. A spring 27, or a coil spring 27, as an elastic element 28 (clamped between the cylinder housing 8 and the roller shoe 9), applies pressure to the roller shoe 9, ensuring that the roller-rolling surface 11 of the working roller 10 remains in contact with the shaft-rolling surface 4 of the drive shaft 2. The roller shoe 9 and the piston 5 thus perform a reciprocating stroke together. The working roller 10 is supported in the roller shoe 9 by a sliding bearing 13. Therefore, the roller shoe 9 with the working roller 10 and the drive shaft 2 with the cams 3 function as a mechanical device 40 for generating the reciprocating motion of the piston 5.

[0059] Inlet valve 19 and outlet valve 20 are mounted or integrated in cylinder head 17. Cylinder head 17 is a component of cylinder 6 or cylinder housing 8. Cylinder head 17 is fixed to cylinder 6 by fixing element 38 as screw 39, and therefore also fixed to cylinder housing 8. A portion of surface 18 of cylinder head 17 forms surface 18 or end 18 of limiting compression chamber 29. Inlet valve 19 includes valve piston 30, elastic element 35 as spring 36, and support element 37 for spring 36. In the closed position, valve piston 30 is fluid-tightly positioned on valve seal seat 32 that surrounds it completely in the tangential direction. Figure 1 The outlet valve 20 similarly includes a valve piston 31 for the outlet valve 20, an elastic element 35 as a spring 36, and a support element 37 for the spring 36. Figure 1 The spring 36 of the outlet valve 20 rests on the valve seat 33 in the closed position of the outlet valve 20. The valve seat 32 for the inlet valve 19 and the valve seat 33 for the outlet valve 20 are configured here to correspond to the geometry constructed on the cylinder head 17. The inlet valve 19 and the outlet valve 20 are pneumatically actuated with valve pistons 30 and 31. Due to the pressure change in the compression chamber 29 during the reciprocating motion of the piston 5, the inlet valve 19 opens and the outlet valve 20 closes during the increase in volume of the compression chamber 29, and vice versa during the decrease in volume of the compression chamber 29 during the reciprocating motion of the piston 5.

[0060] Piston 5 is supported in cylinder 6 and performs an oscillating translational motion along the longitudinal axis 41 of cylinder 6. A drive shaft 2 with cam 3 and a roller shoe 9 with working rollers 10 constitute a mechanical device 40 for the reciprocating motion of piston 5. Mechanical device 40 is arranged in a lubrication chamber 44, which is limited by a housing 45 (partially shown) for both mechanical device 40 and lubrication chamber 44. In lubrication chamber 44, mechanical device 40 is lubricated with a lubricant, such as lubricating oil or fuel. Lubrication is necessary because the bearings of the moving parts are implemented as sliding bearings. Piston compressor 1 compresses, for example, hydrogen for fuel cells or compressed air or oxygen for breathing in compression chamber 29. Therefore, the gas to be compressed must not be contaminated by lubricant from lubrication chamber 44, even by a very small amount. The radial outer side of piston 5, supported on cylinder 6 by piston rings 16, does not allow for complete and tight isolation between lubrication chamber 44 and compression chamber 29 containing the gas to be compressed.

[0061] For this reason, the lubrication chamber 44 is tightly and completely fluid-tightly isolated and sealed from the compression chamber 29 by a diaphragm 34, which serves as a bellows 34. A cylinder 6, which serves as a cylinder housing 8 with a cylinder head 17, and a housing 45 for the lubrication chamber 44 define a cylinder chamber 49. This cylinder chamber 49 is divided by the piston 5 into a first cylinder portion chamber 50 and a second cylinder portion chamber 51, which serve as the compression chamber 29. The diaphragm 34 fluid-tightly divides the second cylinder portion chamber 51 in the radial direction 71 into an internal diaphragm space 52 and an external diaphragm space 53. The radial direction 71 is perpendicular to the longitudinal axis 41 of the cylinder 6. The axial direction 70 is parallel to the longitudinal axis 41 of the cylinder 6. The circumferential direction 72 or tangential direction 72 is oriented circumferentially or tangentially relative to the piston 5 or piston rod 14. The bellows 34, which serves as the diaphragm 34, is made of metal and / or plastic. The plastic is particularly an elastomer. The surface extension dimension of the diaphragm 34 is significantly greater than the thickness of the diaphragm 34. An annular flange 43 is arranged along the longitudinal axis 41 of the cylinder 6 between the cylinder housing 8 and the housing 45 for the mechanical device 40. The lower end region of the bellows 34, which serves as the diaphragm 34, is fixed between the cylinder housing 8 and the flange 43 by pressure locking as a clamping connection. The flange 43 is tightened onto the housing 45 for the mechanical device 40 by fixing elements 38, which serve as screws 39. This pre-tightening of the lower end region of the diaphragm 34 between the cylinder housing 8 and the housing 45 for the mechanical device 40 forms a force-locking sealing device 42. Due to the geometry of the reciprocating compressor 1, without the sealing device 42, lubricant would flow along the diaphragm 34 between the diaphragm 34 and the flange 43 and be discharged into the surrounding environment. The upper end region of the diaphragm 34 is fixed to the lower side of the piston 5 by a fastening device 47. The fastening device 47 is constructed as a material-locking connection, particularly a welded connection and / or an adhesive connection. The fastening device 47 is constructed here in a tangential direction 72, completely surrounding the upper end region of the diaphragm 34 and the piston 5. The diaphragm 34 is also constructed between the upper end of the piston rod 14 and the piston 5. Here, the diaphragm 34, having an extension dimension 48 substantially in the longitudinal axis 41 direction, also includes a disc-shaped or plate-shaped region, which is also partially arranged between the piston rod 14 and the piston 5. This disc-shaped or plate-shaped region of the diaphragm 34 is adapted to the geometry of the lower side of the piston 5 due to its deformability and bendability, and therefore has bends and / or corners in this region. The relevant extension dimension 48 of the bellows 34 in the longitudinal axis 41 direction, i.e., the area of ​​the diaphragm 34 that bears the stroke movement of the piston 5 between the top dead center and the bottom dead center, is significantly larger than the stroke height of the piston 5, i.e., the difference between the top dead center and the bottom dead center of the piston 5. The extension dimension 48 is, for example, 10 cm, and the stroke height of the piston 5 is 0.9 cm. Figure 1In this drawing, due to drawing limitations, the extension dimension 48 and the stroke height of the piston 5 are not drawn to scale. Therefore, the mechanical load on the deformation of the diaphragm 34 is relatively small, as only a small deformation occurs per unit length of the extension dimension 48. Thus, the diaphragm 34 can be constructed not only as a bellows 34 in the relevant area with the extension dimension 48, but also as a simple, fold-free diaphragm. Because the deformation of the diaphragm 34 in the relevant area with the extension dimension 48 is very small, the service life of the diaphragm 34 is at least equal to the service life of the reciprocating compressor 1.

[0062] Figure 3 A second embodiment of the piston compressor 1 is shown. The following description will primarily focus on... Figure 1 The difference is shown in the first embodiment. Figure 3 In the second embodiment shown, the diaphragm 34 is constructed as a single piece in a manner similar to the first embodiment, but without the disc-shaped or plate-shaped region of the diaphragm 34 between the bellows 34 and the substantially cylindrical shell-shaped region having an extension dimension 48 substantially along the longitudinal axis 41 of the cylinder 6. The bellows 34 is fluid-tightly fixed at its upper end by a sealing ring 46 at the lower end of the piston 5 in the region having an annular groove 15. The diaphragm 34 is fluid-tightly connected at its upper end to the lower end of the sealing ring 46 by a sealing device 42 as a fastening device 47. The sealing device 42 and the fastening device 47 between the sealing ring 46 and the diaphragm 34 are formed by a material locking connection, particularly a welded connection and / or an adhesive connection. The welded connection is manufactured, for example, by laser welding. In a similar manner, the upper end of the sealing ring 46 is fixed to the lower end of the piston 5. The sealing device 42 and the fastening device 47 between the sealing ring 46 and the piston 5 are formed by a material locking connection, particularly a welded connection and / or an adhesive connection. The sealing ring 46, as well as the sealing device 42 and the fastening device 47, are constructed to completely surround the diaphragm in the circumferential direction 72. The material-locking connection on the sealing ring 46 and the fastening ring 46 also fluid-tightly seals the diaphragm interior space 52, containing lubricating oil, from the diaphragm exterior space 53. The piston rod 14 is supported in a bearing bushing with a sliding bearing, and lubricating oil flows from the lubrication chamber 44 into the diaphragm interior space 52 due to the gap between the bearing bushing and the piston rod 14. The bearing bushing is fixed to the housing 45.

[0063] Figures 1 to 3 Two embodiments of the piston compressor 1 are shown. These are based on the above description. Figures 1 to 3 The embodiments are used to clearly illustrate the operation of a piston compressor 1 having a bellows 34 as a diaphragm 34. Figures 1 to 3 The embodiment of the piston compressor 1 shown additionally includes a pressure balancing device 54; however, the pressure balancing device 54, as well as, for example, channels 55, 56, are... Figures 1 to 3 Not shown in the diagram. Pressure balancing device 54 is in... Figure 4 A very simplified embodiment of the piston compressor 1 is shown.

[0064] Cylinder 6 defines a cylinder chamber 49. Cylinder chamber 49 also includes the space between piston 5 and mechanical device 40 and / or lubrication chamber 44. Cylinder chamber 49 is divided by piston 5 into a first cylinder portion chamber 50 and a second cylinder portion chamber 51. The first cylinder portion chamber 50 forms compression chamber 29. Space other than piston guide 7 is also considered as cylinder chamber 49 and therefore also as the first cylinder portion chamber 50 and the second cylinder portion chamber 51, for example, the space between piston 5 and mechanical device 40 and / or lubrication chamber 44. Diaphragm 34, acting as bellows 34, divides the second cylinder portion chamber 51 into diaphragm inner space 52 and diaphragm outer space 53. Piston rod 14 is arranged within diaphragm inner space 52. Piston rod 14 is part of mechanical device 40, and the lubrication chamber 44 having mechanical device 40 is not completely fluid-tightly sealed to piston rod 14, such that there is a fluid-guiding connection between lubrication chamber 44 and diaphragm inner space 52. Therefore, the internal space 52 of the diaphragm is loaded with lubricant, especially lubricating oil. The external space 53 of the diaphragm is fluidly connected to the inlet channel 22 via a connecting channel 57 and thus also fluidly connected to the supply container 58 containing the gas to be compressed. Due to this fluid connection via the connecting channel 57, the pressure in the external space 53 of the diaphragm substantially corresponds to the pressure in the inlet channel 22 and / or the supply container 58 according to the time during operation. In particular, pressure fluctuations formed in the inlet channel 22 during the opening or closing of the inlet valve 19 are transmitted to the external space 53 of the diaphragm with a small time delay due to the connection of the connecting channel 57 to the inlet channel 22. Advantageously, therefore, during the intake stroke of the piston 5 for increasing the volume of the compression chamber 29, the pressure in the compression chamber 29 substantially corresponds to the pressure in the external space 53 of the diaphragm. During the stroke of the piston 5 compressing the gas in the compression chamber 29, the pressure in the compression chamber 29 is slightly higher than the pressure in the external space 53 of the diaphragm. Although a slight leak may occur on the piston ring 16, even during the stroke of the piston 5 for compressing the gas, the pressure in the diaphragm outer space 53 always substantially corresponds to the pressure at the inlet channel 22 due to the connecting channel 57, since the gas to be compressed can also flow from the diaphragm outer space 53 into the inlet channel 22 through the connecting channel 57. Leaking gas flowing from the compression chamber 29 along the piston ring 16 and piston guide 7 into the diaphragm outer space 53 can therefore escape through the connecting channel 57. The volume of the diaphragm outer space 53 changes during the stroke of the piston 5, and during this change in volume, the pressure of the balancing fluid (as the gas to be compressed) in the diaphragm outer space 53 substantially corresponds to the pressure in the inlet channel 22, because the connecting channel 57 is designed to be sufficiently sized to allow the balancing fluid to enter and exit the diaphragm outer space 53.

[0065] First channel 55 and second channel 56 lead into the diaphragm interior space 52. Channels 55 and 56 are formed by corresponding holes and a conduit in the cylinder housing 8. First channel 55 is used to continuously introduce balancing fluid into the diaphragm interior space 52. As a delivery device 59 of the compressor 60, such as a diaphragm pump, it continuously delivers air from the ambient environment as balancing fluid through first channel 55 into the diaphragm interior space 52. Second channel 56 is used to introduce balancing fluid into and / or remove balancing fluid from the diaphragm interior space 52. However, depending on the time, either balancing fluid is removed only through second channel 56, or balancing fluid is introduced into the diaphragm interior space 52 through second channel 56. Due to the continuous introduction of balancing fluid through first channel 55, regardless of any leaks or the escape of balancing fluid as gas (i.e., air) outside the lubrication chamber, the balancing fluid introduced through first channel 55 is essentially removed from the diaphragm interior space 52 as excess fluid through second channel 56. Due to the volume change of the diaphragm interior space 52 during the stroke of piston 5, the balancing fluid can also flow into the diaphragm interior space 52 through the second channel 56.

[0066] The balancing fluid delivered through the second channel 56 is either introduced into or discharged from the intermediate container 61. Therefore, the intermediate container 61 acts as a buffer reservoir to compensate for the volume in the diaphragm interior space 52. Due to the connection between the diaphragm interior space 52 and the guiding fluid of the lubrication chamber 44, lubricant, such as lubricating oil, accumulates and enriches in the diaphragm interior space 52, and this lubricant is carried by the balancing fluid introduced into the first channel 55 and delivered together through the second channel 56, such that the mixture of balancing fluid and lubricant is introduced into the intermediate container 61. The volume of the intermediate container 61 is designed to be sufficiently large, for example, greater than 2, 3, 5, or 10 times the maximum volume of the diaphragm interior space 52 at the top dead center of the piston 5. After the introduction of the mixture of balancing fluid and lubricant (i.e., air and lubricating oil from the surrounding environment), the liquid lubricating oil deposits in the bottom region of the intermediate container 61, and air is above the liquid lubricating oil. The pressure acting in the intermediate container 61 is substantially the same as that in the diaphragm interior space 52.

[0067] The discharge passage 62 (which leads to the intermediate container 61 at the bottom region) is fluidly connected to the collection container 66. The collection container 66 has an exhaust valve 67, and due to the fluid connection to the surrounding environment (with an ambient pressure of approximately 1 bar) via the exhaust valve 67, ambient pressure essentially acts within the collection container 66. An actuator 63, which is a valve 64, particularly a proportional valve or servo valve, is installed in the discharge passage 62. Furthermore, a control passage 65 fluidly connects the actuator 63 to the supply container 58 for the gas to be compressed, and therefore also fluidly connects to the inlet passage 22 of the inlet valve 19, and also fluidly connects to the external space 53 of the diaphragm due to the connection passage 57. Through the discharge passage 62, the lubricant, i.e., lubricating oil, accumulated in the intermediate container 61 is essentially introduced into the collection container 66. In some cases, a small amount of balancing fluid can also be introduced into the collection container 66 through the discharge passage 62, for example, when there is essentially no lubricant deposit in the intermediate container 61. Lubricating oil, introduced into collection container 66 through discharge channel 62 under ambient pressure, is then introduced into lubrication chamber 44 via lubricant channel 68 and lubricant delivery device 69, such as a lubricating oil pump. Advantageously, the lubricant introduced into the diaphragm interior space 52 along piston rod 14 can thus be used again to lubricate mechanical device 40. Actuator 63 has a control piston (not shown), and depending on the position of the control piston, lubricant and optional balancing fluid are introduced from intermediate container 61 into collection container 66. The position of the control piston changes the usable flow cross section. The movement of the control piston (not shown) of actuator 63 is controlled by the fact that the control piston is mechanically connected to a control diaphragm (not shown), and the gas to be compressed from control channel 65 applies pressure to the control diaphragm through control channel 65 due to the loading of one side of the control diaphragm with gas to be compressed. Therefore, the gas to be compressed from control channel 65 applies pressure to the control piston in a first direction. In addition, an elastic element (not shown), such as a spring, applies pressure to the control piston in a second direction opposite to the first direction. Therefore, the control diaphragm and elastic element constitute an actuator for moving the control piston according to the pressure in the control channel 65. The actuator for moving the control piston may also be a linear motor, controlled by the pressure of the gas to be compressed detected by a pressure sensor (not shown), for example at the inlet channel 22 and / or connecting channel 57 and / or diaphragm external space 53 and / or supply container 58. The linear motor is controlled and / or regulated by a control and / or regulating unit (not shown) according to the pressure detected by the pressure sensor. Excess balancing fluid and lubricant introduced into the diaphragm internal space 52 are introduced into the intermediate container 61 according to the pressure in the diaphragm internal space 52 and the variable volume of the diaphragm internal space 52.The actuator 63 and the actuator are designed such that the amount of lubricant and optional balancing fluid delivered through the discharge channel 62 makes the pressure in the intermediate container 61 substantially correspond over time to the pressure in the outer space 53 of the diaphragm. Therefore, by means of the actuator 63, according to time and thus also according to the pressure in the control channel 65, i.e. also according to the pressure in the inlet channel 22 and the outer space 53 of the diaphragm, a variable volumetric flow and / or mass flow is introduced through the discharge channel 62 into the collection container 66, such that the pressure in the inner space 52 of the diaphragm is substantially the same as the pressure in the outer space 53 of the diaphragm.

[0068] Overall, the reciprocating compressor 1 according to the invention and the method for operating the reciprocating compressor 1 according to the invention have significant advantages. The introduction and / or extraction of the balancing fluid into and from the diaphragm interior space 52 by means of the pressure balancing device 54 are controlled and / or regulated so that the pressure of the lubricated balancing fluid in the diaphragm interior space 52 substantially corresponds to the pressure of the gas to be compressed in the diaphragm exterior space 53. Consequently, the mechanical load on the diaphragm 34, which serves as the bellows 34, is relatively small, allowing for advantageously smaller wall thicknesses in the bellows 34, and also resulting in less stress, particularly internal stress, within the diaphragm 34. The diaphragm 34 has a long service life with low manufacturing costs.

Claims

1. A reciprocating compressor (1) for compressing gas, comprising: - Cylinder (6) - Piston (5), which is supported in the cylinder (6), - Cylinder chamber (49), which is divided by the piston (5) into a first cylinder partial chamber (50) and a second cylinder partial chamber (51), the first cylinder partial chamber serving as a compression chamber (29) for compressing gas. - Inlet valve (19) for the compression chamber (29). - Outlet valve (20) for the compression chamber (29). - A mechanical device (40), to which the piston (5) is mechanically connected for the reciprocating motion of the piston (5). - A lubrication chamber (44), in which the mechanical device (40) is at least partially arranged, and in which the mechanical device (40) is lubricated with a lubricant. - A diaphragm (34) fluidly and sealingly separates the lubrication chamber (44) from the compression chamber (29) by means of the diaphragm (34), and the diaphragm (34) arranged in the second cylinder partial chamber (51) divides the second cylinder partial chamber (51) into a diaphragm inner space (52) and a diaphragm outer space (53). Its features are, The reciprocating compressor (1) includes a pressure balancing device (54) having channels (55, 56, 57) for introducing balancing fluid into and / or exporting from the diaphragm interior space (52) based on the pressure in the diaphragm exterior space (53), and / or conversely, introducing balancing fluid into and / or exporting from the diaphragm exterior space (53) based on the pressure in the diaphragm interior space (52), so as to achieve substantially the same pressure in the diaphragm interior space (52) and the diaphragm exterior space (53).

2. The reciprocating compressor according to claim 1, Its features are, The reciprocating compressor includes a connecting channel (57), and the diaphragm outer space (53) is fluidly connected via the connecting channel (57) to the inlet channel (22) of the inlet valve (19), and in particular to the supply container (58) of the gas to be compressed, so that the pressure of the fluid in the diaphragm outer space (53) is equalized with the pressure in the inlet channel (22) of the inlet valve (19).

3. The piston compressor according to claim 1 or 2, Its features are, The diaphragm interior space (52) is provided with a first channel (55) for introducing the balancing fluid into the diaphragm interior space (52) and a second channel (56) for introducing the balancing fluid into the diaphragm interior space (52) and / or exporting it from the diaphragm interior space.

4. The piston compressor according to claim 3, Its features are, The reciprocating compressor includes a conveying device (59), by means of which the compressor (60) can introduce a balancing fluid, particularly air, into the diaphragm interior space (52) through the first channel (55).

5. The piston compressor according to claim 4, Its features are, During operation of the reciprocating compressor (1), the balancing fluid can be continuously introduced into the diaphragm interior space (52) via the first channel (55) by means of the conveying device (59).

6. The piston compressor according to one or more of claims 3 to 5, Its features are, The piston compressor (1) includes an intermediate container (61), and the second passage (56) leads into the intermediate container (61).

7. The piston compressor according to one or more of claims 3 to 6, Its features are, The second channel (56) can guide the balancing fluid and preferably the lubricant.

8. The reciprocating compressor according to claim 6 or 7, Its features are, Excess balancing fluid introduced into the diaphragm interior space (52) can be exported from the diaphragm interior space (52) and introduced into the intermediate container (61) through the second channel (56).

9. The piston compressor according to one or more of claims 6 to 8, Its features are, The piston compressor (1) includes an actuator (63) by means of which the equilibrium fluid in the intermediate container (61) can be discharged according to the pressure in the outer space (53) of the diaphragm so as to achieve substantially the same pressure in the intermediate container (61) and the outer space (53) of the diaphragm.

10. The reciprocating compressor according to claim 9, Its features are, The actuator (63) is a valve (64), particularly a servo valve (64), which is fluidly connected via a control channel (65) to the inlet channel (22) of the inlet valve (19), particularly to the supply container (58) of the gas to be compressed, so as to control the actuator (63) by means of the pressure of the gas to be compressed in the inlet channel (22) of the inlet valve (19).

11. The reciprocating compressor according to claim 9 or 10, Its features are, The piston compressor (1) includes a discharge passage (62) and a collection container (66), and fluid, especially balancing fluid and / or lubricant, discharged from the actuator (63) can be introduced into the collection container (66) through the discharge passage (62).

12. A method for operating a reciprocating compressor (1) for compressing gas, comprising the following steps: - The cylinder chamber (49) is divided by the piston (5) into a first cylinder partial chamber (50) and a second cylinder partial chamber (51), the first cylinder partial chamber serving as a compression chamber (29) for compressing gas. - The gas to be compressed is introduced into the compression chamber (29) through the inlet valve (19). - The gas introduced into the compression chamber (29) is compressed by means of a piston (5) in such a way that the piston (5) performs a stroke movement to reduce the volume of the compression chamber (29). - The gas compressed in the compression chamber (29) is discharged from the compression chamber (29) through the outlet valve (20). - The reciprocating motion of the piston (5) is achieved by means of a mechanical device (40) mechanically connected to the piston (5). - The mechanical device (40) is lubricated with a lubricant in a lubrication chamber (44), the mechanical device (40) being at least partially disposed in the lubrication chamber (44). - The lubrication chamber (44) is fluidly and sealedly separated from the compression chamber (29) by means of a diaphragm (34), and the second cylinder partial chamber (51) is divided by the diaphragm (34) into an inner space (52) and an outer space (53). Its features are, The balancing fluid is introduced into and / or exported from the inner space (52) of the diaphragm according to the pressure of the fluid in the outer space (53) of the diaphragm, and / or conversely, the balancing fluid is introduced into and / or exported from the outer space (53) of the diaphragm according to the pressure of the fluid in the inner space (52) of the diaphragm, so as to achieve substantially the same pressure in the inner space (52) and the outer space (53) of the diaphragm.

13. The method according to claim 12, Its features are, The balancing fluid is introduced, particularly continuously and / or persistently, into the diaphragm interior space (52) through a first channel (55) for introducing the balancing fluid, and excess fluid introduced into the diaphragm interior space (52) through the first channel (55) is discharged from the diaphragm interior space (52) through a second channel (56), particularly continuously and / or persistently.

14. The method according to claim 13, Its features are, The volumetric flow of fluid guided through the second channel (56) as a balancing fluid and / or lubricant is controlled and / or regulated so that substantially the same pressure exists in the inner space (52) and the outer space (53) of the diaphragm.

15. The method according to one or more of claims 12 to 14, Its features are, The outer space of the diaphragm (53) is fluidly connected to the inlet channel (22) of the inlet valve (19) via a connecting channel (57), particularly to the supply container (58) of the gas to be compressed, such that the pressure of the fluid in the outer space of the diaphragm (53) substantially corresponds to the pressure in the inlet channel (22) of the inlet valve (19), in such a way that the gas to be compressed is introduced into and / or exported from the outer space of the diaphragm (53) through the connecting channel (57).

Images