DK170430B1

DK170430B1 - Cylinder liner for internal combustion engine

Info

Publication number: DK170430B1
Application number: DK102293A
Authority: DK
Inventors: Thomas Synnestvedt Knudsen
Original assignee: Man B & W Diesel Gmbh
Priority date: 1993-09-13
Filing date: 1993-09-13
Publication date: 1995-08-28
Also published as: DK102293D0; WO1995008058A1; DK102293A; TW268992B

Description

DK 170430 B1DK 170430 B1

Den foreliggende opfindelse angår en cylinder foring til en forbrændingsmotor med et stempel med mindst én stempelring, omfattende mindst én indad åben, rundt-gående reces med olietilførsel placeret over øverste 5 stempelrings bunddødpunkt.The present invention relates to a cylinder liner for an internal combustion engine having a piston having at least one piston ring, comprising at least one inwardly open, circumferential oil supply recess located above the bottom dead center of the 5 piston ring.

Cylinderforinger af denne art kendes eksempelvis fra EP-patentskrift nr. 0 299 174 og uprøvet japansk patentansøgning nr. 61-279 716. Disse skrifter viser cylinderforinger med olietilførsel i et eller flere 10 niveauer, hvorved der i hvert niveau tilføres olie til en rundtgående reces eller til en række ved siden af hinanden liggende recesser, som derved tilvejebringer en diskontinuert rundtgående reces, hvorfra olien flyder ind i cylinderforingens indre. Ifølge EP-0299174og 15 JP 61-279 716 skal disse smørerecesser placeres henholdsvis i området 5-40% af slaglængden under top-dødpunktet og 15-60% af slaglængden under topdødpunktet.Cylindrical liners of this kind are known, for example, from EP patent application 0 299 174 and unproven Japanese patent application No. 61-279 716. These writings show cylinder liners with oil supply at one or more 10 levels, whereby at each level oil is supplied to a circular recess or to a series of adjacent recesses, thereby providing a discontinuous circumferential recess from which the oil flows into the interior of the cylinder liner. According to EP-0299174 and 15 JP 61-279 716, these lubrication recesses must be located in the range 5-40% of the stroke below the peak dead center and 15-60% of the stroke below the peak dead center respectively.

Det har været observeret i praksis, at der i en forbrændingsmotor kan optræde rivninger mellem stempel-20 skørtet og cylinderforingen. Sådanne rivninger er tilbøjelige til at opstå i den del af foringen, som ikke bliver udsat for stempelringenes indkøring af dens overflade, dvs. den del af foringen, som ligger under nederste stempelrings bunddødpunkt, men som bestryges 25 af stempelskørtet og derfra brede sig op gennem cylinderen. Hvis rivningerne breder sig til et område med højt kontakttryk mellem stempelring og cylinderforing, vil stempelringen også rive. Det resulterer i en hærdning af stempelringen og i sidste ende en meget 30 hurtig udslidning af cylinderforingen.It has been observed in practice that in an internal combustion engine tear may occur between the piston skirt and the cylinder liner. Such tearing tends to occur in the part of the liner which is not exposed to the piston rings' entry into its surface, i.e. that portion of the liner which is below the bottom dead center of the piston ring, but which is wiped 25 by the piston skirt and from there spreads through the cylinder. If the shreds extend to an area of high contact pressure between piston ring and cylinder liner, the piston ring will also tear. This results in a hardening of the piston ring and ultimately a very rapid wear of the cylinder liner.

Formålet med opfindelsen er at forhindre sådanne rivninger, skulle de opstå, i at brede sig. Dette opnås ved hjælp af en cylinderforing af den indledningsvis omtalte art, som er særegen ved at en anden rundtgående 35 reces er placeret mere end 65% af stemplets slaglængde DK 170430 B1 2 under den øverste stempelrings topdødpunkt, hvilken anden reces kun er åben mod cylinderens indre. En sådan reces stopper udbredelsen af eventuelle rivninger og hindrer således, at en opstået rivning breder sig op - 5 langs cylinderforingens væg.The object of the invention is to prevent such tearing should they arise from spreading. This is achieved by means of a cylinder liner of the type mentioned initially, which is special in that another circumferential 35 recess is placed more than 65% of the stroke of the piston DK 170430 B1 2 below the top dead center of the piston ring, which second recess is open only to the cylinder internal. Such a recess stops the propagation of any tearing and prevents the formation of tearing from spreading along the wall of the cylinder liner.

Recessen strækker sig fortrinsvis kontinuert rundt langs cylinderforingens inderside.Preferably, the recess extends continuously along the inside of the cylinder liner.

I en udførelsesform, hvor cylinderforingen er til en totakts motor og omfatter skylleluftporte er der 10 fortrinsvis placeret en reces over skylleluftportene.In one embodiment, where the cylinder liner is for a two-stroke engine and comprises purge air ports, a recess is preferably placed over the purge air ports.

Ved denne placering vil recessen ud over at virke som rivningsbarriere også virke som oliereservoir og opfange en del af den smøreolie, som af stempelringene skubbes ned ad under ekspansionsslaget. Denne olie går sædvan-15 ligvis tabt gennem skylleluf tport ene, når stempelringene passerer disse. I stedet opsamles i det mindste en del af denne olie i den rundtgående reces og under stemplets opadgående bevægelse vil olien så igen komme ud af reservoiret og hjælpe med til at smøre stempelringene, 20 som nu er på vej op i foringen. Dermed kan der spares på smøreolien.At this location, in addition to acting as a demolition barrier, the recess will also act as an oil reservoir and intercept a portion of the lubricating oil pushed by the piston rings down during the expansion stroke. This oil is usually lost through the rinsing air when the piston rings pass through it. Instead, at least part of this oil is collected in the circumferential recess and during the upward movement of the piston the oil will then again come out of the reservoir and help to lubricate the piston rings, which are now on their way into the casing. This can save on the lubricating oil.

Ved en cylinder foring for en totakts motor og omfattende skylleluftporte er der fortrinsvis placeret -en reces under skylleluftportene, da det ved denne 25 motortype navnlig er i dette område, at rivninger opstår.Preferably, at a cylinder liner for a two-stroke engine and comprising purging air ports, a recess is located below the purging air ports, as it is particularly in this area that tearing occurs in this type of engine.

Opfindelsen vil i det følgende blive forklaret nærmere ved hjælp af et udførelseseksempel under henvisning til tegningen, hvis eneste figur skematisk 30 viser et halvt snit gennem en cylinder. 'The invention will now be explained in more detail by way of an exemplary embodiment with reference to the drawing, the only figure of which schematically shows half a section through a cylinder. '

Figuren viser et halvt snit af en cylinder af en totakts forbrændingsmotor med en cylinderforing 1, et . * cylinderdæksel 2, et ventilsæde 3 og et ventillegeme 4. Cylinderforingen 1 og cylinderdækslet 2 er ved 35 hjælp af stagbolte 5 spændt fast til en cylinderramme DK 170430 B1 3 6. Cylinderforingen 1 er udvendigt forsynet med recesser og boringer for køling og har skylleluftporte 9. Endelig er cylinderforingen 1 indvendigt forsynet med en rundtgående reces 7 med en olietilførsel 8 5 for smøring af stemplet.The figure shows a half section of a cylinder of a two-stroke internal combustion engine with a cylinder liner 1, one. * Cylinder cover 2, valve seat 3 and valve body 4. Cylinder liner 1 and cylinder cover 2 are fastened to a cylinder frame by means of rod bolts 5. Finally, the cylinder liner 1 is provided internally with a circumferential recess 7 with an oil supply 8 5 for lubricating the piston.

Ud over recessen 7 er cylinderforingen 1 forsynet med to andre recesser henholdsvis 10 og 11, som fortrinsvis strækker sig ubrudt rundt langs cylinderforingen l'e indervæg og kan have vilkårlige tvær-10 snit. Recessen 10 er placeret under skylleluftkanaler-ne 9 og recessen 11 er placeret over dem. Recesserne 10 og 11 bevirker at rivninger, som undertiden ses optræde mellem cylinderforingen 1 og skørtet af det stempel, som under drift vil bevæge sig op og ned i 15 cylinderen, standses dvs. at de ikke breder sig op over den reces 10, 11, som ligger nærmest over det sted, hvor rivningen først optræder. Ved hjælp af recesserne ifølge opfindelsen undgås dermed, at rivninger forplanter sig til et område af cylinderf oringen, hvor 20 kontakt trykket mellem stempelringe og cylinderforing er højt og hvor sådanne rivninger vil gøre alvorlig skade ved at bevirke en meget hurtig udslidning af cylinderforingen.In addition to the recess 7, the cylinder liner 1 is provided with two other recesses 10 and 11, respectively, which preferably extend uninterruptedly around the inner wall of the cylinder liner and can have arbitrary cross-sections. Recess 10 is located beneath flushing air ducts 9 and recess 11 is located above them. The recesses 10 and 11 cause tearing, which is sometimes seen to occur between the cylinder liner 1 and the skirt of the piston which during operation will move up and down the cylinder, ie. that they do not extend beyond the recess 10, 11 which is closest to the place where the demolition first occurs. By means of the recesses according to the invention, it is thus avoided that tearing propagates to an area of the cylinder liner where the contact pressure between piston rings and cylinder liner is high and where such tearing will do serious damage by causing a very rapid wear of the cylinder liner.

Den over skylleluftkanalerne 9 beliggende reces 25 11 har desuden den fordel, at olie, som under motorens drift under ekspansionslaget drives nedad af stempel-ringene, trænger ind i recessen 11, som derved virker som et reservoir. Under stemplets opadgående bevægelse vil olien atter komme ud af recessen 11 og virke 30 smørende på stempelringene, som nu er på vej op gennem cylinderforingen 1.The recess 25 11 located above the rinsing air ducts 9 also has the advantage that oil which is driven downwards by the piston rings during operation of the motor during the expansion layer, enters the recess 11, which thus acts as a reservoir. During the upward movement of the piston, the oil will again emerge from the recess 11 and act 30 lubricating the piston rings, which are now on their way up through the cylinder liner 1.

I det viste eksempel er recessen 10 placeret ca. l/3 af skylleluftportene 9's højde under dem, medens recessen 11 er placeret ca. en porthøjde over skylle-35 luftportene 9. Der kan efter behov anvendes flereIn the example shown, recess 10 is located approx. 1/3 of the height of the flushing ports 9 below them, while recess 11 is located approx. a gate height above the flushing air ports 9. Several may be used as required

Claims

A cylinder liner for an internal combustion engine having a piston having at least one piston ring, comprising at least one inwardly open, circumferential recess (7) with oil supply (8) located above the bottom dead center of the piston ring - characterized in that another circumferential recess (10, 11 is located more than 65% of the stroke of the piston below the top dead center of the upper piston ring, which second recess (10, 11) is open only to the interior of the cylinder.

A cylinder liner according to claim 1, characterized in that said second recess (10, 11) extends continuously around the cylinder for the inside of the (1).

Cylinder liner according to claim 1 or 2 for a two-stroke engine and comprising rinsing air ports (9), characterized in that said second recess (10) is located below the rinsing air ports (9).

Cylinder liner according to claims 1-3 for a two-stroke engine and comprising rinsing air ports (9), characterized in that a second recess (11) is located above the rinsing air ports (9).