EP1082534A1 - Ensemble piston-cylindre - Google Patents

Ensemble piston-cylindre

Info

Publication number
EP1082534A1
EP1082534A1 EP99917969A EP99917969A EP1082534A1 EP 1082534 A1 EP1082534 A1 EP 1082534A1 EP 99917969 A EP99917969 A EP 99917969A EP 99917969 A EP99917969 A EP 99917969A EP 1082534 A1 EP1082534 A1 EP 1082534A1
Authority
EP
European Patent Office
Prior art keywords
piston
arrangement according
cylinder
guide
parts
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99917969A
Other languages
German (de)
English (en)
Inventor
Werner Jahn
Robert Marschall
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Uti Holding and Management AG
Original Assignee
Uti Holding and Management AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from DE1998115989 external-priority patent/DE19815989A1/de
Priority claimed from DE1998115988 external-priority patent/DE19815988C1/de
Application filed by Uti Holding and Management AG filed Critical Uti Holding and Management AG
Publication of EP1082534A1 publication Critical patent/EP1082534A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J9/00—Piston-rings, e.g. non-metallic piston-rings, seats therefor; Ring sealings of similar construction
    • F16J9/28—Piston-rings, e.g. non-metallic piston-rings, seats therefor; Ring sealings of similar construction of non-metals
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F3/00—Pistons 
    • F02F3/0084—Pistons  the pistons being constructed from specific materials
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J1/00—Pistons; Trunk pistons; Plungers
    • F16J1/02—Bearing surfaces
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J10/00—Engine or like cylinders; Features of hollow, e.g. cylindrical, bodies in general
    • F16J10/02—Cylinders designed to receive moving pistons or plungers
    • F16J10/04—Running faces; Liners
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2201/00—Metals
    • F05C2201/02—Light metals
    • F05C2201/021—Aluminium
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2201/00—Metals
    • F05C2201/04—Heavy metals
    • F05C2201/0433—Iron group; Ferrous alloys, e.g. steel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2201/00—Metals
    • F05C2201/04—Heavy metals
    • F05C2201/0433—Iron group; Ferrous alloys, e.g. steel
    • F05C2201/0448—Steel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2203/00—Non-metallic inorganic materials
    • F05C2203/08—Ceramics; Oxides
    • F05C2203/0865—Oxide ceramics
    • F05C2203/0882—Carbon, e.g. graphite

Definitions

  • the invention relates to a piston-cylinder arrangement according to the preamble of claim 1, comprising a cylinder, along the inner bore formed as a piston guide surface a sliding portion of a piston is axially displaceable, and a piston to which a connecting rod can be articulated by means of a bolt, wherein at least two cylindrical and circumferential sliding sections delimiting the piston radially for support against the guide surface of the cylinder, which are detachably arranged on the piston by two parts of the piston, at least one of which penetrates a central opening in the sliding sections.
  • the invention further relates to a guide arrangement according to the preamble of claim 16, comprising a first part and a second part, along the surface of which is designed as a guide surface and facing the first part, a sliding section of the first part can be displaced.
  • PRIOR ART DE-A-29 12 786 shows a piston for internal combustion engines and a method for producing such a piston which is formed from carbon produced by pyrolysis.
  • the carbon is penetrated by a large number of carbon fibers, which in this way form a matrix for the whole of the piston.
  • the production of the known piston by pyrolysis is complex, because shrinking processes during production must be taken into account when dimensioning the raw piston (blank).
  • the carbon fibers which are indispensable for stability and strength, are to be laid in such a complicated manner that openings such as bores and the like, which are provided in the pistons by subsequent machining, do not damage the carbon fiber matrix, since this means a dramatic loss in strength.
  • the known piston is provided on the combustion side with a protective layer made of silicon carbide, which has to be manufactured in a complex manner by plasma application.
  • This pairing of materials is problematic in terms of production technology and In particular with regard to the running surface of the cylinder due to the differences in hardness of SiC and carbon, it is unsuitable because the piston has sliding surfaces of different hardness, as a result of which undesired wear is generated in the sliding surfaces.
  • the piston pin arranged in the piston for the articulation of a connecting rod is also made of carbon, whereby this material can only be subjected to a small load for the tensile loads occurring in the articulation of connecting rods, in contrast to pressure loads.
  • DE-A-30 01 921 shows a piston which corresponds to the aforementioned known piston and which is produced with the aid of a negatively reworked mold.
  • This piston also has a completely cylindrical outer wall which has a piston pin bore perpendicular to the main axis of the piston for fixing the piston pin and is formed in the region of the piston head with three piston ring grooves for receiving piston rings.
  • US-A-2,792,265 describes a piston-cylinder arrangement which is used in compressors and pumps and in which the two graphite elements arranged on the core, which define the sliding surfaces on their radial outer surfaces, are detachably arranged.
  • the core is formed in two parts, which two parts are mutually braced by a screw.
  • the two graphite elements surround radially cylindrical sections of the core with different outer diameters, so that the inner diameter of the two graphite elements is also different.
  • the shoulders in the core do not fix the graphite elements axially, rather spring elements are provided for this purpose, which due to their inherent tension prevent axial slipping as long as the lubrication in the cylinder prevents the occurrence of higher forces due to relative movements.
  • the known structure is therefore not suitable for piston-cylinder arrangements which run as provided in the invention without lubricants, for example for air compressors.
  • the decoupling of the two rings by means of a spring also causes radial play 3
  • piston pin 2 is arranged eccentrically, so that pulling and pushing movements are transmitted non-uniformly to the sliding sections. This results in a disadvantageous tilting moment of the piston in the cylinder during the return stroke, as a result of which the proximal sliding section wears out more quickly than the distal sliding section, which can result in sealing problems and thus an uneven running.
  • DE-C-41 22 090 shows a graphite piston for an internal combustion engine made of a binder-free carbon (mesophase), the piston crown of which is coated with a protective layer of combustion residues.
  • the known piston has several ring-like recesses, such that only narrow webs come into abutment against the circumferential surface of the cylinder.
  • This graphite piston is only suitable for a small number of materials or coatings on the inside of the cylinder.
  • the piston crown must be covered in a complex manner with a protective layer in applications without combustion.
  • the narrow webs affect the tilting stability of the piston in the cylinder.
  • US-A-1, 467.255 shows the use of pistons made of amorphous "monolithic" carbon graphite, the bottom surface and adjacent peripheral surfaces of which are sealed against oxidation by electrolytic application of a thin metal layer. Furthermore, the carbon graphite can be solidified by introducing molten metal into the porous structure.
  • the manufacture of such a piston is complex, expensive and not suitable for modern high-performance piston-cylinder arrangements. It is also proposed to surround the region of the articulation of the connecting rod on the piston pin with a metallic sleeve such that the inner surface of the piston is shielded from the connecting rod, but not the piston pin. This construction requires complex lubrication and is also difficult to manufacture in terms of production technology. In addition, a large part of the piston must be replaced in order to adapt to a cylinder running surface in order to be able to use the linkage to the connecting rod for another piston material in adaptation to the cylinder sliding surfaces.
  • EP-B-0 258 330 shows a piston-cylinder arrangement of a piston engine with a piston made of carbon, which has at least one piston ring which projects radially over the circumferential surface of the piston.
  • the piston ring is constructed in several parts, with an expansion element that is in contact with supports a compression spring against the inner wall of the piston ring groove, prestresses two essentially semicircular piston half rings in the direction of the running surface.
  • the production of such compression springs is complex and prone to defects in use.
  • the end of the expansion element facing away from the spring or the end of the piston half abutting against its conical surface abuts against the running surface of the surrounding cylinder or a cylinder liner, so that a mechanical extension that is selective due to the axial displacement of the piston to a line Load on the tread results, which leads to the formation of grooves and increased wear on the tread or the piston ring, ultimately leading to leakage.
  • the carbon proposed for use is of low strength, which is why it is proposed to reinforce it with carbon fibers or to use additives to form a modified carbon.
  • DE-A-34 06 479 shows a multi-part piston, the components of which consist of fiber-reinforced carbon.
  • the known piston has a first piston part which is essentially hollow cylindrical and which extends over the entire length of the piston and circumferentially defined a single sliding surface.
  • the second piston part is a plug-in part which is inserted into the first piston part, the two piston parts being designed to form a positive fit and being held against one another by a concentric piston pin bore through which a piston pin can be inserted. Because of the large sliding surface, the forces for the piston are high and the susceptibility to wear of the known piston is significant.
  • DE-A-30 40 125 shows a multi-part piston for reciprocating piston engines, which is partly made of fiber-reinforced plastic and which comprises a piston crown, a piston skirt and piston pin eyes as separately manufactured components.
  • DE-A-44 37 558 shows a method for producing a high-strength isotropic graphite, the flexural strength of which permits use for pistons in gasoline engines.
  • the one material of the pairing of the sliding section-guide surface is selected from the group comprising polycrystalline diamond, amorphous hydrocarbon, tetragonally coordinated carbon and metal-containing hydrocarbon, and that other pairing material is selected from the group consisting of mesophase graphite and ultra fine grain graphite.
  • the piston-cylinder arrangement creates a piston, which is supported with its sliding sections, which are preferably designed as closed rings, against the guide surface of the cylinder.
  • the two ring areas are arranged at a distance from one another, the distance between the ring areas preferably making up at least half the axial extent of the narrower of the two ring sections and advantageously being twice that of the two rings larger in axial extent.
  • the two ring-shaped sliding sections prevent the piston from tilting in the guide surface of the cylinder, which improves the smooth running of the piston-cylinder arrangement and reduces the noise generated when running. At the same time, the cylinder is sealed against the piston. 7
  • the two sliding sections can optionally be connected to one another in one piece, in that the distance between the sliding sections is provided by a recess in the peripheral wall of the ring or a constriction in the case of archetypal shapes.
  • the sliding sections are provided on two different rings each, which have the same outer diameter and which are held at a predetermined distance from one another by a separate spacer or in the axial continuation of at least one ring. It is possible to split the rings or to split them, e.g. to form from two or three ring segments which form the ring when assembled, the piston parts also fixing these ring parts by axial clamping, so that installation in a cylinder is possible without problems.
  • the material of the rings defining the sliding sections is expediently a material of high flexural strength, for example of more than 95 N / mm 2 and in particular of more than 120 N / mm 2 , ideally even of more than 140 N / mm 2 , which have also been manufactured to the associated cylinder dimension with high surface accuracy, for example by external cylindrical grinding. It is understood that the spacer need not be manufactured cost-effectively with the same dimensional accuracy and surface quality, which is why a piece with a smaller outside diameter that is different from the rings is advantageously provided. This spacer can always be made of the same material for a modular piston production, while the rings having the sliding sections are provided from a material selected to match the guide surface of the cylinder or its material. This makes the piston much more versatile than a one-piece piston.
  • the two rings having the sliding sections and the spacer preferably have the same inner diameter, so that they can be mounted on one another on a shaft with the corresponding outer diameter so as to be axially displaceable.
  • the rings having the sliding sections preferably lie essentially in the region of the axial ends of the piston, as a result of which good guidance of the piston in the cylinder is achieved.
  • the ring opening of the sliding sections is penetrated by at least one piston part in at least one area of the axial extent. 8th
  • this piston part also has a receiving space for a piston pin and a pivoting space for a connecting rod articulated around the piston pin.
  • the second piston part which can be connected to the first piston part, constitutes an end boundary of the piston.
  • the connection is preferably releasable, for example in the manner of a bayonet catch or a screw connection. This makes the piston-cylinder arrangement particularly easy to repair by making it possible to replace sliding sections.
  • the piston parts are preferably connected by plugging or by means of an interference fit, so that fast production times are achieved.
  • a particularly powerful piston-cylinder arrangement is achieved in that, according to the invention, the one material of the pairing of the sliding section guide surface is selected from the group comprising polycrystalline diamond, amorphous hydrocarbon, tetragonally coordinated carbon dioxide and metal-containing hydrocarbon, and the other material of the pairing is formed from mesophase graphite or from ultra-fine grain graphite.
  • Ultrafine-grain graphite for example, is supplied by POCO in the market.
  • this arrangement is thus virtually infinite, so that it can be used in locations that are no longer readily accessible, e.g. due to radioactive, chemical or bacterial contamination.
  • This primary shaping step is expediently followed by a grinding step, but advantageously only the sliding sections have to be subjected to it, while the other piston parts, which do not come into engagement with the piston guide surface of the cylinder, have already been completed. It is also possible to carry out this grinding step in the cylinder and thus to use the hardness of the material of the piston guide surface in addition to the seal for surface treatment.
  • the flexural strength of the mesophase graphite exceeds 120 N / mm 2 and advantageously enables the creation of a single phase Materials.
  • Fig. 1 shows a longitudinal sectional view of a first embodiment of a piston-cylinder arrangement according to the invention, in which the cylinder and piston are shown pulled apart.
  • FIG. 2 shows a top view of the piston from FIG. 1 from the direction of arrow II.
  • FIG. 3 shows the piston from FIG. 1 in an exploded longitudinal section.
  • FIG. 4 shows a longitudinal sectional view of the piston-cylinder arrangement from FIG. 1 in the assembled state with piston pin and connecting rod.
  • FIG. 5 shows a cross-sectional illustration of the piston-cylinder arrangement from FIG. 4 along the axially offset line V-V.
  • Fig. 6 shows a longitudinal sectional view of a second embodiment of a piston-cylinder arrangement according to the invention, in which the cylinder and piston are shown pulled apart.
  • FIG. 7 shows the piston from FIG. 6 in an exploded longitudinal sectional view.
  • FIG. 1 The components of a piston-cylinder arrangement 1 are shown in longitudinal section in FIG. 1, the piston 2 being separated from the interior of the cylinder 3 for better illustration.
  • the piston-cylinder arrangement is used in a compressor.
  • the cylinder 3 is a hollow cylinder, for example made of metal or a ceramic, the inner bore 4 of which partially or preferably completely forms a piston guide surface 5 for the axial displacement of the piston 2.
  • the piston guide surface or the corresponding section of the inner circumference of the bore 4 of the cylinder is designated by the reference number 5. It 10
  • section which is designed as a guide surface 5 is essentially axially limited by the piston stroke.
  • bore 4 of cylinder 3 is coated with a hard layer 6, which forms guide surface 5.
  • This layer is a few tenths of a millimeter or even micrometers thick and is therefore only indicated as a line.
  • hard materials come into consideration as the applied layer 6, that is to say carbides, oxides, nitrides and diamond coatings and compounds from the groups mentioned above. It is advantageously possible to select the layer from the same material as the material of the cylinder 3 and to harden the layer by infiltrating foreign atoms, by radiation, by CVD or PVD methods, chemical or electrochemical deposition or by other suitable methods or means .
  • the bore 4 in the cylinder 3 may be expedient to first prefabricate the bore 4 in the cylinder 3 very precisely to size, for example by lapping or grooving, and then to further process it.
  • the blank for the cylinder 3 is manufactured close to the final shape and finished covering the areas not to be coated or tempered to form the layer 6 in a process step subsequent to the production. This advantageously makes it possible for small and medium-sized series of cylinders 3 to be produced while maintaining the highest tolerances, in particular with regard to the bore 4.
  • the method outlined above also makes it possible to adapt the type of layer 6 in the separate method step to the specific use, in particular to a fluid to be conveyed and its chemical properties and reactivity, without this resulting in any significant disadvantages in terms of cost.
  • the piston 2 is a multi-part modular unit, which can be seen particularly well in FIG. 3.
  • the piston 2 comprises an end part 7 and a connecting part 8 made of titanium, which respectively define the piston head 7a and the connecting rod side. It is alternatively possible to select other suitable materials, in particular aluminum, steel or in particular graphite, instead of titanium.
  • the piston 2 further comprises a proximal, closed ring 9 and a distal, closed ring 10, the closed cylindrical circumference of which defines a sliding section 9a or 10a of the piston. Between the two rings 9 and 10 is also a ring 1 1
  • Spacer 11 is provided with a hollow cylindrical structure, the proximal and distal end faces of which abut the proximal ring 10 or the distal ring 9 and whose cylinder diameter is smaller than that of the two rings 9, 10. Also the end part 7 or the connecting part 8 have smaller outer diameters than the rings 9, 10.
  • the distal sliding section 9a or the proximal sliding section 10a of the distal ring 9 or the proximal ring 10 define the outer surface of the piston 2 which is supported against the guide surface 5 of the cylinder 3, as can also be seen better in FIG. 4.
  • the front part 7 has in its piston crown 7a two blind holes 12 (well shown in FIG. 2) which are intended for the engagement of a clamping tool, not shown. However, it is possible to replace the blind holes 12 with other cutouts or profiles suitable for the engagement of clamping tools, or even to omit them entirely.
  • the end part 7 On the side facing the piston crown 7a, the end part 7 has a hollow cylindrical section 7b which is flanged to it and has an annular cross-section, the outer surface of which is provided with an external thread 7c.
  • the inside of the flanged hollow cylinder is formed on the inside proximally with a phase of 45 °.
  • the blind bores 12 are expediently arranged in the extension of the one-piece flange section 7b, in order to be able to transmit torques in the case of screw connections at low cost.
  • the end part 7 has, on the side of the disk facing away from the piston crown 7a, an annular groove 13 which is concentric with the disk and is suitable for receiving a sealing ring (not shown).
  • the end part 7 functioning as a piston cover is a one-piece part made of titanium. It is alternatively possible to design the front part 7 from aluminum or from ceramics, metallic materials having the advantage that they have high tensile strength and, moreover, the toothing can be easily produced using known means.
  • the connecting part 8 is advantageously made from the same material as the end part 7.
  • the connecting part 8 defines a piston base body which has an internal thread 8c adapted to the external thread 7c of the end part 7.
  • the threads 7c and 8c are cut in such a way that outside the thread pair 7c, 8c there are no contacts between the parts 7, 8, so that the thread pairing creates a positive and preferably also non-positive connection transition.
  • Connection piece 8 thus defines an axial annular gap 14 or a gap 15, the axial extent of the gap 15 being essentially the same as that of the gap 14 (cf. FIG. 1). It is also possible to provide only one of the two gaps 14, 15 and otherwise provide a contact between the two parts 8, 9 or even to eliminate both gaps 14 and 15. Especially with metallic materials, however, it is advantageous if the gaps 14, 15 as a space for expansion of the material due to thermal expansion or the like and as a game for tolerances of the other parts of the piston 3, as will be explained below, between the front part and Connection part 8 are clamped.
  • the connecting part 8 has a cylindrical basic shape, the proximal end of which protrudes circumferentially in the manner of a collar 16 over the circumference of the cylinder.
  • the forwardly facing annular surface 16a of the collar 16 serves as a stop for the proximal edge surface 10c of the proximal ring 10 when it overlaps the cylindrical peripheral wall 8d of the connecting part 8.
  • the connecting part 8 is constructed as a hollow cylinder, with the central bore 8d coaxial with the entire part being penetrated in the middle by two extension pieces 17a, 17b, the mutually facing surfaces 18a, 18b of the extension pieces 17a, 17b running essentially parallel to one another.
  • the extension pieces 17a, 17b are penetrated by a cylinder bore extending transversely to the main axis of the connecting part 8 in such a way that the surfaces 18a, 18b of the extension pieces 17a, 17b are penetrated essentially in the center normal to their surfaces 18a, 18b.
  • the bore 19 cut out of the extension pieces 17a, 17b and the connecting part 8, the axis 19a of which is shown in broken lines, forms a receptacle for a cylindrical piston pin 20 which is shown in FIGS. 4 and 5 is shown.
  • circumferential recesses 21a-21d are provided in pairs in the shaft extension 8a of the connecting part 8.
  • the punctures 21a to 21d serve to accommodate seals, preferably made of an elastomer material, which, because of their pretensioning, permit better centering of the ring parts seated on the shaft 8a.
  • the ring walls delimiting the slots are designed to be as long as possible and with the formation of corresponding labyrinth-like bends so as not to impair the sealing of the piston chamber.
  • the prestressing of the seal causes the ring components to be readjusted continuously.
  • the front part 7 is screwed to the connecting part 8 and the proximal ring 10, the spacer 11 and the distal ring 9 are thrown over the shaft section 8a in the order mentioned.
  • the parts 7 to 11 mentioned are axially clamped, the shaft section 8a of the connecting part 8 being connected to the inner bores 10b, 11b, 9b of the rings 10, 11, 9 essentially without play, so that the five components of the piston 3 are aligned coaxially with respect to the piston axis 3a.
  • the outer circumferential wall 11a of the spacer 11 jumps back a little in relation to the outer circumferential surfaces of the rings 9, 10, which are designed as a distal sliding section 9a and as a proximal sliding section 10a, so that it contacts the guide surface 5 of the cylinder 3 even when thermally induced Expansion does not come into contact.
  • the effective area of the sliding sections is kept small in order to reduce friction, and on the other hand, due to the spaced design of the two sliding sections 9a, 10a, increased tilting stability and guidance accuracy are achieved.
  • the axial extension of the spacer 11 is preferably approximately twice as large as that of the larger of the two rings 9, 10.
  • the spacer 11 As an alternative to the three-part construction with rings 9 and 10 and with spacer 11, it is possible to form these three parts in one piece, either the material of the one-piece part being the ring material or the material of the sliding sections, or in the area of the sliding sections on the one-piece part corresponding coatings are made.
  • the particular advantage of the separate configuration of the spacer 11 is twofold: on the one hand, through the suitable choice of material for the spacer 11 in adaptation to the thermal expansion and the dimensions of the rings 9, 10 on the one hand and of the front part 7, connecting part 8, on the other hand, a particularly advantageous one Corrective created under thermal stress, which makes it possible to reduce thermally induced stresses.
  • the spacer 11 - as can be seen particularly well on the left in FIG. 5 - frames the piston pin 20 at a maximum of two precise points, 14
  • the piston pin 20 is not only floating in its circumference through the bore 19, but also in its axial extent within the limitation by the spacer 11.
  • the piston pin 20 is made of steel, for example, and is advantageously hollow-drilled.
  • a connecting rod 22 articulated on the piston pin 20 is fixed by means of a needle bearing or bush 23, slide bearing or ball bearing, which is not shown in the drawing, and accordingly the stroke of the piston 3 in the cylinder 2 is extremely precise.
  • the connecting rod 22 is shown schematically in FIGS. 4 and 5.
  • the assembly of the piston 2 with the articulated connecting rod 22 now takes place in that the piston pin 20 is first inserted through the bore 19 into the connecting part 8, through the bore 8d of which a connecting rod end 22 with the connecting rod eye has been inserted.
  • the piston pin 20, which extends through the connecting rod eye is preferably made to measure or even as a press fit, so that, depending on the design, the piston pin 20 is connected in a rotationally fixed manner to the connecting rod end 22 and / or to the connecting piece 8. Then the proximal ring 10, then the spacer 11 and finally the distal ring 9 are then thrown over the shaft piece 8a of the connecting piece 8 with the articulated connecting rod 22, the spacer 11 completely closing the bore 19 with the inserted piston pin 20.
  • the front part 7 is then screwed onto the connection part 8 in the manner of a cover, the fixing or the force transmission to the connection part 8 in the direction of rotation, e.g. can be carried out with the aid of the connecting rod and the fixing or power transmission to the end part 7 with a clamping tool, not shown, by means of the blind holes 12.
  • the finished piston 2 can then be inserted into the cylinder 3 to form the piston-cylinder arrangement 1 according to the invention.
  • a particular advantage of the piston-cylinder arrangement 1 according to the invention is that the modularly constructed piston 2 is in the simplest way to the media that are to be conveyed with the piston-cylinder arrangement 1 or to the material of the guide surfaces 5 of the cylinder 3 can be adjusted.
  • the series lengths can be increased and the manufacturing costs can be advantageously reduced. Installation is extremely simple and easy to maintain. 15
  • the distal ring 9 of the piston 2 is circumferentially formed on its distal surface with a projection 9c which completely surrounds the peripheral surface of the disk of the end part 7, as a result of which the clearance of the piston-cylinder arrangement is created 1 is not enlarged unnecessarily.
  • the disk of the end part 7 it is alternatively possible to design the disk of the end part 7 to be somewhat larger in diameter, although this may not be larger or equal to the diameter of the ring 9.
  • a particular advantage of the construction of the piston 2 according to the invention is that the piston head is essentially influenced by the material selection of the end part 7, so that materials susceptible to oxidation for the ring may only have to be treated or coated along a small area.
  • the piston 2 according to the invention is also particularly suitable for internal combustion engines.
  • FIGS. 6 and 7 A further exemplary embodiment of a piston-cylinder arrangement according to the invention is described with reference to FIGS. 6 and 7. Parts that are comparable in the previous exemplary embodiment are denoted by the same reference symbols.
  • the piston-cylinder arrangement V in turn consists of a cylinder 3 and a piston 2, the cylinder 3 being unchanged from the exemplary embodiment in FIGS. 1 to 5 and therefore having the same reference numerals.
  • the piston 2 in turn has an end part 7 and a connecting part 8 which axially penetrate the sections of the piston on which the cylindrical and circumferential sliding sections 9a, 10a are arranged.
  • the structure of the end part 7 or the connecting part 8 is essentially the same as in the previous embodiment, which is why the same reference numerals designate the same parts and a more detailed description can be omitted.
  • a bore 19 is provided for receiving a piston pin 20, which is inserted essentially coaxially to the axis 19a of the bore 19.
  • grooves or recesses 21 can be provided as in the previous exemplary embodiment, but these are not provided in the present embodiment. It is also possible to provide blind holes in the manner of blind holes 12 in the previous exemplary embodiment in order to screw the end part 7 with its external thread 7c to the internal thread 8c of the connecting part 8 in order to produce an axial tension.
  • the connecting part 8 also has a collar 16, the inward shoulder 16a of which tension together with the corresponding counterpart of the end part 7th 16
  • the piston crown 7a and the connecting part 8 are made, for example, from the same materials as in the previous exemplary embodiment, and the sleeve 23 can also be made from the same material as the distal ring 9 and the proximal ring 10 in the previous example.
  • the sleeve 23 has a distal one Sliding section 9a and a proximal sliding section 10a, which also have a ring cross section and which are circumferentially designed to come into sliding contact with the guide surface 5 of the cylinder 3.
  • a spacer ring 24 is formed in one piece with the two rings which carry the sliding sections 9a, 10a.
  • the sliding sections 9a, 10a are separated from a spacer section 11a of the spacer ring 24 by a step in the outer surface, which is provided with reference number 25 and is circumferential. This ensures that the contact is made only by the sliding sections 9a, 10a with the guide surface 5 of the cylinder 3, whereby the cylindricity and the coaxiality of the two ring surfaces to one another is better than with multi-part sleeves. It is also possible to enlarge the sealing and guide sections, which improves the service life and increases the tightness. Finally, the number of contacting interfaces is reduced from 8 to 4, so the manufacturing tolerances have less negative effects on smoothness, temperature increases and reliability.
  • each of the two sliding sections 9a, 10a is located exclusively on the one hand and on the other hand the axis 19a of the bore 19 for the piston pin 20, so that the forces and moments transmitted via the connecting rod 22, which is not shown here, are uniform provided on both sides of the axis 19a 17
  • the mesophase graphite consists of a binder-free carbon, a so-called mesophase.
  • the raw material on which the mesophase graphite is based can preferably be obtained from coal and petroleum residues in pitches which remain, for example, as an intermediate product in the liquid phase pyrolysis of hydrocarbons. It consists essentially of polyaromatics.
  • the polyaromatics can be formed by carbonization and graphitization into mesophase spherulites, which represent the grains of a phase of the material (grain size between 0.1 and 10 ⁇ m).
  • mesophase spherulites are binder-free and are therefore far superior to common graphite types such as pressed or electrographite in their field properties, particularly in their bending compressive strength.
  • bending strengths of over 150 MPa can be achieved.
  • the manufacture of the rings 9, 10 can advantageously - starting from spherulites - by injection molding as a so-called near-net 18th
  • shape components take place, with a sintering step following a shaping step which also permits complicated geometries.
  • the component manufactured in this way here a ring, consists of an isotropic material.
  • corresponding counter-forms in particular bushes and / or mandrels, are used for the shaping.
  • Subsequent machining can then be carried out to achieve preferred surface properties or predetermined dimensional accuracy, for example by grinding, grooving, lapping. Due to the favorable strength properties of the rings, subsequent surface treatment is generally not necessary.
  • open or closed porosities between 0.05 and 30% can be achieved.
  • the guide surface 6 in the cylinder 3 consists of a coating of polycrystalline diamond (PCD).
  • PCD polycrystalline diamond
  • DLC - Diamond like Carbon diamond-like carbon coatings
  • metal-containing hydrocarbon Mo: CH
  • amorphous hydrocarbon a: CH
  • tetragonally coordinated carbon a: C
  • piston-cylinder arrangement 1 is thus advantageously suitable as a dry runner.
  • Another advantage of the piston-cylinder arrangement 1 according to the invention is that piston rings, which are always difficult to assemble due to their slotted design, can be dispensed with.
  • the rings out of the mesographite after the primary shaping step e.g. to grind with a diamond-coated grinding wheel.
  • This grinding step is expediently effected, however, by the rings in the cylinder 3 being displaced back and forth against the diamond coating, as a result of which no mechanical removal takes place after a running-in phase and a particularly tight piston-cylinder unit is created.
  • the counter forms of the rings are also diamond coated.
  • a one-piece part comprising the two rings 9, 10 and a spacer 24 can also be produced in the manner described. It also goes without saying that, in the same way described, only the distal or the proximal sliding sections can be applied to a substrate ring, for example made of ceramic or another material, for example to a continuous ring of the thickness of the spacer 11. It also goes without saying that the freedom left for the selection of the suitable material combination is available for the optimization with regard to the intended use (medium).
  • proximal components 8, 10 and the distal components 7, 9 can each be formed in pairs as one-piece components in a piston according to the invention, and then preferably in the manner described above. 20th
  • the piston-cylinder arrangement according to the invention is advantageously used as a reciprocating piston machine, compressor, internal combustion engine or the like.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Pistons, Piston Rings, And Cylinders (AREA)

Abstract

L'invention concerne une ensemble de guidage, notamment un ensemble piston-cylindre, comprenant un cylindre (3), dans lequel une section de glissement d'un piston (2) peut coulisser axialement le long de l'alésage interne dudit cylindre, ledit alésage servant de surface de guidage de piston (6), et un piston (2) sur lequel peut être articulée une bielle au moyen d'un arbre. Au moins deux sections de glissement (9a, 10a) cylindriques et périphériques, délimitant radialement le piston (2), sont placées de manière libérable sur le piston (2), par l'intermédiaire de deux parties (7, 8) du piston (2), pour que ce dernier prenne appui contre la surface de guidage (6) du cylindre (3), au moins une de ces deux parties passant à travers un passage central des sections de glissement (9a, 10a). Les forces et les couples sont répartis de manière homogène sur au moins deux sections de glissement car, dans la direction axiale du piston, les sections de glissement sont placées à l'extérieur de l'axe de l'arbre. De plus, au moins une (9a) desdites sections de glissement (9a, 10a) est placée entièrement d'un côté de l'axe de l'arbre (20) et au moins une autre (10a) desdites sections de glissement est placée entièrement de l'autre côté de l'axe de l'arbre (20). Les sections de glissement (9a, 10a) sont fixées à une distance axiale fixe (11) l'une par rapport à l'autre, et le transfert de force entre l'arbre et les sections de glissement (9a, 10a) est prévu exclusivement par l'intermédiaire des parties centrales (7, 8) du piston (2). On obtient en outre un appariement tribologique avantageux en sélectionnant un matériau de l'appariement "section de glissement (9a, 10a) - surface de guidage (6)" dans le groupe comprenant le diamant polycristallin, les hydrocarbures amorphes, le carbone tétragonal et les hydrocarbures métalliques, et l'autre matériau de l'appariement dans le groupe comprenant le graphite à phase mésomorphe et le graphite à grains ultrafins.
EP99917969A 1998-04-09 1999-04-09 Ensemble piston-cylindre Withdrawn EP1082534A1 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
DE19815988 1998-04-09
DE1998115989 DE19815989A1 (de) 1998-04-09 1998-04-09 Kolben-Zylinder-Anordnung
DE19815989 1998-04-09
DE1998115988 DE19815988C1 (de) 1998-04-09 1998-04-09 Kolben-Zylinder-Anordnung
PCT/EP1999/002400 WO1999058839A1 (fr) 1998-04-09 1999-04-09 Ensemble piston-cylindre

Publications (1)

Publication Number Publication Date
EP1082534A1 true EP1082534A1 (fr) 2001-03-14

Family

ID=26045392

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99917969A Withdrawn EP1082534A1 (fr) 1998-04-09 1999-04-09 Ensemble piston-cylindre

Country Status (4)

Country Link
EP (1) EP1082534A1 (fr)
AU (1) AU3605799A (fr)
DE (1) DE19980856D2 (fr)
WO (1) WO1999058839A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102016108900B4 (de) * 2016-05-13 2019-05-16 Phitea GmbH Kolben für eine Hubkolbenbrennkraftmaschine und Verfahren zum Herstellen eines solchen

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB439301A (en) * 1933-06-21 1935-12-04 Ltd Co Formerly Skoda Works Improvements in and relating to piston engines with self-lubricating packing rings
FR1122703A (fr) * 1954-04-17 1956-09-12 Siemag Siegener Masch Bau Segments de guidage et d'étanchéité pour pistons en plusieurs parties de machines de travail et de moteurs
DE1252487B (fr) * 1963-07-27
GB1413114A (en) * 1971-12-11 1975-11-05 Hepworth & Grandage Ltd Reciprocating compressors or pumps
GB1584590A (en) * 1977-12-06 1981-02-11 Kawasaki Heavy Ind Ltd Internal combustion engine cylinder and piston arrangements
JP2648519B2 (ja) * 1989-10-03 1997-09-03 日立粉末冶金株式会社 シンクロナイザーハブの製造方法
SE9201678D0 (sv) * 1992-05-27 1992-05-27 Hoeganaes Ab Pulverkkomposition foer tillsats i jaernbaserade pulverblandningar

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9958839A1 *

Also Published As

Publication number Publication date
WO1999058839A1 (fr) 1999-11-18
DE19980856D2 (de) 2001-09-13
AU3605799A (en) 1999-11-29

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