AT527942B1 - Oscillating piston compressor - Google Patents

Abstract

The invention relates to an oscillating piston compressor (1) comprising a piston (9, 10) and a cylinder component that forms at least part of a cylinder chamber (7, 8). At least one of these components is designed as a sintered component, with at least one of its axial end faces (16-27) being formed, at least in some regions, as a closed surface to at least 98%. Furthermore, the component has at least 98% closed sintered pores, starting from the surface and extending to a depth (29) of at least 0.05 mm.

Description

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Description

[0001] The invention relates to a piston for a reciprocating piston compressor comprising a piston ring on which a separating slide is arranged, wherein the piston ring and the separating slide have first and second axial end faces, and wherein the piston ring and the separating slide are designed as a sintered component and the first and/or second axial end faces are designed at least in regions to at least 98% as closed surfaces.

[0002] Furthermore, the invention relates to a cylinder component, in particular a cylinder disc or a cover disc or an intermediate disc, for an oscillating piston compressor, comprising a component body which has at least a first and at least a second axial end face, wherein the component body is designed as a sintered component and at least one of the first and/or second axial end faces is designed, at least in regions, to at least 98% as a closed surface.

[0003] Furthermore, the invention relates to an oscillating piston compressor comprising a piston and a cylinder component.

[0004] Oscillating piston compressors (also referred to as rotary compressors) are known in the art in a wide variety of designs. For example, DE 10 2022 132 001 B3 describes an oscillating piston compressor comprising a compressor housing with a working chamber and a piston rotating eccentrically therein, with a separating slide that divides the working chamber into a pressure chamber and a suction chamber. The separating slide is part of a rotary-thrust joint that seals the pressure chamber from the suction chamber. On the suction chamber side, the rotary-thrust joint is formed by a joint piece that is in thrust-jointed contact with the separating slide on the one hand and in rotary-jointed contact with the compressor housing on the other. The rotary-thrust joint is formed on the pressure chamber side by rotary-thrust-jointed contact of the separating slide with the compressor housing.

[0005] From DE 10 2022 131 321 B3 a rotary compressor is known, comprising a cylinder chamber which is radially delimited by a cylinder disc and axially by a cover disc which bears against an axial end face of the cylinder disc, a piston rotating in the cylinder chamber, a separating slide which divides the cylinder chamber into a suction chamber and a pressure chamber, an outlet channel extending from the pressure chamber with a first channel section running in the cylinder disc and a second channel section running in the cover disc, and a flutter valve arranged in the cover disc, which separates the first channel section and the second channel section from one another in the closed state and connects them to one another in the open state, and which is in sealing contact with the axial end face of the cylinder disc in the closed state.

[0006] US 2012/0087819 A1, JP 2012-117409 A and JP 2017190765 A describe oscillating piston compressors in which the piston ring and the separating slide or a cylinder component are designed as a sintered component.

[0007] The invention is based on the object of simplifying the manufacture of an oscillating piston compressor for conveying a wide variety of fluids.

[0008] The object of the invention is achieved with the piston mentioned at the outset, in which the piston ring and the separating slide have at least 98% closed sintered pores on the first and/or second axial end faces, starting from the surface to a depth of at least 0.05 mm.

[0009] In addition, the object of the invention is also achieved with the cylinder component mentioned at the outset, in which the component body has at least 98% closed sintered pores on the first and/or second axial end face, starting from the surface to a depth of at least 0.05 mm.

[0010] Furthermore, the object of the invention is achieved with the oscillating piston compressor mentioned at the outset, which has the piston and/or the cylinder component according to the invention.

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[0011] The advantage here is that components of an oscillating piston compressor can be manufactured relatively easily, even with complex geometries, so that design changes to simplify an oscillating piston compressor are not necessary. Should such changes nevertheless be made, the process for manufacturing the components of the oscillating piston compressor can be adapted relatively easily. Furthermore, the powder-metallurgical production of at least one component of the oscillating piston compressor has the advantage of weight reduction, since sections below the closed surface can be formed with pores. The latter also enable a certain degree of elasticity of the component, which can improve the operation of the oscillating piston compressor. The lower weight enables designs of an oscillating piston compressor with a lower moving mass. Furthermore, the components can be used to improve the NVH (noise-vibration-harshness) behavior of an oscillating piston compressor.

[0012] Because the piston ring and the separating slide have at least 98 closed sintered pores on the first and/or second axial end faces, starting from the surface to a depth of at least 0.05 mm, and/or because the component body has at least 98 closed sintered pores on the first and/or second axial end faces, starting from the surface to a depth of at least 0.05 mm, the operational reliability of the oscillating piston compressor can be improved, so that even problematic fluids can be pumped with the oscillating piston compressor. Fluids that can diffuse into materials due to their molecular size and are potentially corrosive can be problematic. In addition, by closing the pores, an increase in the efficiency of the oscillating piston compressor's operation can be achieved, since fluid flows through the component body are avoided.

[0013] To further improve the property(ies) of the component of the oscillating piston compressor, according to embodiment variants of the invention, it can be provided that the piston ring and the separating slide have a coating on the first and/or second axial end faces and/or that the component body has a coating on the first and/or second axial end faces. With the coating, a closed surface of the component of the oscillating piston compressor can be achieved even without material compaction, so that sections of the component can be formed more precisely with a closed surface. In addition, the coating can also impart another surface property to the component, such as improved lubricity. However, the component can also be additionally compacted at least in sections below the coating and thus already have a closed surface. For example, the surface can already be at least 98% closed below the coating.

[0014] A simple formation of the closed surface as well as larger pore-free layer thicknesses can be achieved with embodiment variants of the invention, according to which the piston ring and the separating slide are blasted on the first and/or second axial end faces and have a surface roughness with an average roughness depth Rz according to DIN EN ISO 4287:2010 between 5 µm and 150 µm and/or the component body is blasted on the first and/or second axial end face and has a surface roughness with an average roughness depth Rz according to DIN EN ISO 4287:2010 between 5 µm and 150 µm. This can increase the reliability of preventing infiltration of the component with the fluid to be pumped. In addition, the mechanical load-bearing capacity of the component of the oscillating piston compressor can be improved. The formation of the surface with a surface roughness in the mentioned area has the advantage that the running-in of the component during the initial commissioning of the oscillating piston compressor can be improved, since it can provide areas that can serve to absorb abraded particles.

[0015] A reduction in abrasion at least during the running-in phase of the oscillating piston compressor can be achieved according to further embodiments of the invention, according to which the piston ring and the separating slide are machined on the first and/or second axial end faces, in particular honed at least once, and/or the component body is machined on the first and/or second axial end face, in particular at least once

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is honed.

[0016] According to other embodiments of the invention, it can be provided that all surfaces of the piston ring and the separating slide are designed as closed surfaces and/or that all surfaces of the component body are designed as closed surfaces. This makes it possible to better protect the oscillating piston compressor from corrosive media that could affect the oscillating piston compressor from the outside.

[0017] According to embodiments of the invention, it can be provided that all surfaces of the piston ring and the separating slide are designed according to the features of the axial surfaces according to at least one of the aforementioned embodiments and/or that all surfaces of the component body are designed according to the features of the axial surfaces according to at least one of the aforementioned embodiments. Thus, the aforementioned effects can also be achieved for these surfaces.

[0018] For a better understanding of the invention, it is explained in more detail with reference to the following figures.

[0019] They show in a simplified, schematic representation: [0020] Fig. 1 shows a side view of an oscillating piston compressor; [0021] Fig. 2 shows a cylinder disc and a piston of an oscillating piston compressor;

[0022] Fig. 3 shows a section of a cross section through a component of the oscillating piston compressor.

[0023] By way of introduction, it should be noted that in the variously described embodiments, identical parts are provided with identical reference numerals or identical component designations, whereby the disclosures contained in the entire description can be applied mutatis mutandis to identical parts with identical reference numerals or identical component designations. Furthermore, the positional information chosen in the description, such as top, bottom, side, etc., refers to the directly described and illustrated figure, and these positional information must be applied mutatis mutandis to the new position in the event of a change in position.

[0024] Fig. 1 shows a simplified representation of an oscillating piston compressor 1. The oscillating piston compressor 1 is used to compress a gaseous fluid, e.g., a refrigerant such as carbon dioxide or propane. One possible application for the oscillating piston compressor 1 is, for example, an air conditioning system, particularly in a motor vehicle. However, other applications are possible, so the oscillating piston compressor 1 is not limited to air conditioning systems.

[0025] The oscillating piston compressor 1 according to Fig. 1 is designed as a two-cylinder compressor. However, it is possible for the oscillating piston compressor 1 to have only one cylinder or more than two cylinders.

[0026] The oscillating piston compressor 1 according to Fig. 1 has, in the specified order, a first cover plate 2, a first cylinder plate 3 lying against it, in particular directly lying against it, an intermediate plate 4 lying against it, in particular directly lying against it, a second cylinder plate 5 lying against it, in particular directly lying against it, and a second cover plate 6 lying against it, in particular directly lying against it. The first and second cylinder plates 3, 5 have a first and second cylinder chamber 7, 8, respectively, in which a first and second piston 9, 10 is arranged eccentrically. The first and second pistons 9, 10 are arranged on an eccentric shaft 11, for example on eccentric discs of an eccentric shaft 11. The first and second pistons 9, 10 are driven by the eccentric shaft 11. The eccentric shaft 11 can, for example, be connected to an electric motor that sets the eccentric shaft 11 in rotation.

[0027] The first and second cylinder chambers 7, 8 are delimited in the axial direction by the first and second cover plates 2, 6 and the intermediate plate 4, respectively.

[0028] The first and second pistons 9, 10 can be of identical design. The embodiments

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to the first piston 9 can therefore be transferred to the second piston 10, so that only the first piston 9 will be discussed below.

[0029] As can be seen from Fig. 2, the first piston 9 comprises a piston ring 12 and a separating slide 13. The separating slide 13 divides the cylinder chamber 7 into a suction chamber 14 and a pressure chamber 15, so that the fluid is sucked in and compressed by the movement of the piston 9.

[0030] These general principles and the described components of the oscillating piston compressor 1 are known per se, so that for further details reference is made to the relevant prior art. In particular, this also concerns the supply of the fluid to and the discharge of the compressed fluid from the cylinder chamber 7 (or cylinder chamber 8), which are only indicated in Fig. 2.

[0031] The piston ring 12 and the separating slide 13 have first and second axial end faces 16, 17. Furthermore, the first and second cover plates 2, 6, the first and second cylinder plates 3, 5 and the intermediate plate 4 have axial end faces 18 to 27.

[0032] To simplify the description, the first and second pistons 9, 10, the first and second cover plates 2, 6, the first and second cylinder plates 3, 5, and the intermediate plate 4 are generally referred to below as components of the oscillating piston compressor 1. These embodiments are applicable accordingly to the piston(s) 9, 10 and/or at least one of the cylinder components.

[0033] It should be mentioned at this point that the at least one piston 9, 10 and/or the at least one cover plate 2, 6 and/or the at least one cylinder plate 3, 5 and/or the at least one intermediate plate 4 can be designed according to the invention. Accordingly, in the following, instead of "component," the terms "piston 9 and/or piston 10" and/or "cover plate 2 and/or cover plate 6" and/or "cylindrical plate 3 and/or cylinder plate 5" and/or "intermediate plate 4" can be read.

[0034] Other components of the oscillating piston compressor 1 can also be designed according to the invention.

[0035] The component is preferably formed in one piece. It is made from a sintered material, preferably a metallic one, for example, sintered steel, using a powder metallurgy process. These processes are known per se, so further discussion is unnecessary. For the sake of completeness, it should be noted that these processes include at least the steps of pressing the powder or powder mixture into a green compact in a mold and sintering the green compact to form the component.

[0036] It is provided that at least one of the aforementioned end faces 16 to 27 is designed as a closed surface, at least in part, in particular entirely. Within the meaning of the invention, this means that there are no (open) pores on this surface into which the fluid to be compressed can diffuse. In this at least one region, the surface is designed to be at least 98% closed within the meaning of the invention. Reference is made to Fig. 3, which shows a simplified section of the piston 9. As can be seen, the surface 16 is designed without open pores, and in particular is pore-free. This design can be achieved using several methods. For example, the component can be infiltrated (or impregnated) on at least one end face 16 to 27, i.e., the pores can be filled with another material, e.g., copper or a polymeric synthetic resin. The infiltration of the component with the additional material can be achieved using negative pressure and/or atmospheric pressure (pressure of the surrounding atmosphere) and/or positive pressure. After infiltration with a precursor of a polymer resin, this can be cured, for example, at elevated temperatures or using UV or electron beams, etc.

[0037] In addition, according to one embodiment, it is possible for the component to be surface compacted after infiltration. This has the advantage that the infiltration or impregnating agent is also exposed to the compaction process. The component is thus better suited for use in oscillating piston compressors 1, which are subject to higher pressures.

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By “co-compressing” the infiltration or impregnating agent, its leakage during operation of the oscillating piston compressor 1 can be avoided.

[0038] According to another embodiment, the at least one end face 16 to 27 can be provided with a coating 28, at least in the region of the closed surface. The coating 28 can be, for example, a polymer coating. For example, it can be formed from a polyamide, a polyamideimide, or a polyester. Optionally, the coating 28 can contain at least one solid lubricant, such as molybdenum disulfide, graphite, hexagonal boron nitride, etc., and/or at least one hard material, such as a ceramic hard material, for example, dialuminum trioxide, etc.

[0039] According to a further embodiment, the at least one end face 16 to 27 can be densified, preferably entirely, at least in the region of the at least one closed surface. It is provided that the component has a densified zone on the at least one end face 16 to 27, which, starting from the surface to a depth 29 of at least 0.05 mm, in particular between 0.05 mm and 5 mm, has at least 98%, in particular at least 99%, preferably 100%, closed sintered pores, i.e., in particular, no (through) channels.

[0040] Alternatively or additionally, it is also possible for the component to have a density of at least 98%, in particular at least 99%, preferably 100%, of the theoretical material density due to compaction to a depth 29 of at least 0.05 mm, in particular between 0.05 mm and 5 mm. The theoretical material density is the density that the material used exhibits when processed using a casting process. By compacting the material to its maximum density down to this minimum depth, the oscillating piston compressor 1 can be better prepared for difficult operating conditions.

[0041] The compaction of the component on at least one of the end faces 16 to 27 can be carried out in one or more stages in a compaction tool, into or through which the component is pressed or pressed with a punch. Preferably, the compaction takes place in several stages without relaxing the component between the compaction stages, i.e., a compaction tool is used that does not have a section in which the diameter or cross-section of the opening in which the component is received increases along the longitudinal center axis through the compaction tool in the compaction direction. However, it can be provided that a single relaxation section with an increasing diameter or cross-section is formed, which is arranged immediately before the last compaction section.

[0042] According to another embodiment of the invention, it can be provided that, alternatively or additionally, the at least one end face 16 to 27 is blasted at least partially, preferably entirely, with a blasting medium, for example (metallic) balls or metal particles or ceramic particles. Preferably, a blasting medium made of a stainless steel powder produced by gas atomization is used. The blasting particles can have a diameter between 15 μm and 1 cm.

[0043] Preferably, the blasting is carried out in such a way that a surface with a surface roughness with an average roughness depth Rz according to DIN EN ISO 4287:2010 between 5 µm and 150 µm, for example between 10 µm and 100 µm, is created. This can be achieved, for example, by higher speeds at which the particles impact the at least one end face 16 to 27 and/or by the quantities of particles per unit time that impact the at least one end face 16 to 27, thereby enabling better plasticization of the sintered material.

[0044] The compaction of at least one end face 16 to 27 can be performed after sintering. Alternatively or additionally, the compaction can be performed on the green compact after powder pressing.

[0045] The at least one end face 16 to 27 can also be subjected to at least one processing, in particular a machining operation. This is preferably carried out after compaction. Machining alone is not sufficient to produce the closed

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provide a uniform surface. However, subsequent machining has advantages in terms of surface quality. Preferably, the component is honed one or more times before machining. Additionally or alternatively, at least one end face 16 to 27 can also be ground or finely turned. Turning, etc., can also be carried out as machining. However, honing and/or grinding allows for a smaller allowance than with turning, which can reduce the compacted zone. This, in turn, has the advantage of weight reduction and the associated effect, as already explained above with regard to weight reduction.

[0046] According to a further embodiment, all surfaces of the component, i.e., the axial end faces 16 to 27 and the radial surfaces or the lateral surfaces of the component, are designed as closed surfaces. The above statements regarding the axial end faces 16 to 27 can also be applied to the other surfaces of the component.

[0047] It is further possible that the component is processed using different methods, in particular compacted, or that the closed surfaces of different end faces 16 to 27 of the component are produced using different methods, in particular selected from the above-mentioned methods for producing the closed surface.

[0048] The invention relates not only to at least one of the components of the oscillating piston compressor 1 per se, but also to the method for its production within the scope of the method steps mentioned above.

[0049] For the sake of clarity, it should finally be pointed out that, in order to better understand the structure of the component or of the oscillating piston compressor 1, these have been shown partly out of scale and/or enlarged and/or reduced in size.

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LIST OF REFERENCE SYMBOLS

1 Oscillating piston compressor 2 Cover plate 3 Cylinder disc

4 Intermediate disc 5 Cylindrical disc

6 Cover plate 7 Cylinder chamber

8 cylinder chamber

9 pistons

10 pistons

11 Eccentric shaft

12 piston ring

13 separating slides

14 Suction chamber

15 Printing room

16 Frontal surface

17 Frontal surface

18 Frontal surface

19 Frontal surface

20 frontal area

21 Frontal surface

22 Frontal surface

23 Frontal surface

24 Frontal area

25 frontal area

26 Frontal surface

27 Frontal surface

28 Coating

29 depth

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Claims (13)

x bes AT 527 942 B1 2025-08-15 Ss N patent claims 1. Piston (9, 10) for an oscillating piston compressor (1), comprising a piston ring (12) on which a separating slide (13) is arranged, wherein the piston ring (12) and the separating slide (13) have first and second axial end faces (16, 17), and wherein the piston ring (12) and the separating slide (13) are designed as a sintered component and the first and/or second axial end faces (16, 17) are designed, at least in regions, as at least 98% closed surfaces, characterized in that the piston ring (12) and the separating slide (13) have at least 98% closed sintered pores on the first and/or second axial end faces (16, 17) starting from the surface down to a depth (29) of at least 0.05 mm. 2. Piston (9, 10) according to claim 1, characterized in that the piston ring (12) and the separating slide (13) have a coating (28) on the first and/or second axial end faces (16, 17). 3. Piston (9, 10) according to claim 1 or 2, characterized in that the piston ring (12) and the separating slide (13) are blasted on the first and/or second axial end faces (16, 17) and have a surface roughness with an average roughness depth Rz according to DIN EN ISO 4287:2010 between 5 µm and 150 µm. 4. Piston (9, 10) according to one of claims 1 to 3, characterized in that the piston ring (12) and the separating slide (13) are machined on the first and/or second axial end faces (16, 17), in particular honed at least once. 5. Piston (9, 10) according to one of claims 1 to 4, characterized in that all surfaces of the piston ring (12) and the separating slide (13) are designed as closed surfaces. 6. Piston (9, 10) according to claim 5, characterized in that all surfaces of the piston ring (12) and the separating slide (13) are designed according to the features of the axial end faces (16, 17) according to at least one of claims 2 to 4. 7. Cylinder component, in particular cylinder disk (3, 5) or end disk (2, 6) or intermediate disk (4), for an oscillating piston compressor (1), comprising a component body which has at least a first and at least a second axial end face (18-27), wherein the component body is designed as a sintered component and at least one of the first and/or second axial end faces (18-27) is designed, at least in regions, as a closed surface to at least 98%, characterized in that the component body has at least 98% closed sintered pores on the first and/or second axial end faces (18-27) starting from the surface down to a depth (29) of at least 0.05 mm. 8. Cylinder component according to claim 7, characterized in that the component body has a coating (28) on the first and/or second axial end faces (18-27). 9. Cylinder component according to claim 7 or 8, characterized in that the component body is blasted on the first and/or second axial end face (18-27) and has a surface roughness with an average roughness depth Rz according to DIN EN ISO 4287:2010 between 5 µm and 150 µm. 10. Cylinder component according to one of claims 7 to 9, characterized in that the component body is machined on the first and/or second axial end face (18-27), in particular is honed at least once. 11. Cylinder component according to one of claims 7 to 10, characterized in that all surfaces of the component body are designed as closed surfaces. 12. Cylinder component according to claim 11, characterized in that all surfaces of the component body are designed according to the features of the axial end face (18-27) according to at least one of claims 8 to 10. x bes AT 527 942 B1 2025-08-15 Ss N 13. Oscillating piston compressor (1) comprising a piston (9, 10) and a cylinder component which forms at least part of a cylinder chamber (7, 8), characterized in that the piston (9, 10) is designed according to one of claims 1 to 6 and/or the cylinder component is designed according to one of claims 7 to 12. 2 sheets of drawings