SE444356B

SE444356B - KOLVTETNING

Info

Publication number: SE444356B
Application number: SE8403629A
Authority: SE
Inventors: J B S Andren; S-E Gustavsson; F L Johansson
Original assignee: Atlas Copco Ab
Priority date: 1984-07-09
Filing date: 1984-07-09
Publication date: 1986-04-07
Also published as: SE8403629L; DE8519534U1; SE8403629D0

Description

s4o3629f2 10 _15 20_ 25 30 35 .. -w Iz . s4o3629f2 10 _15 20_ 25 30 35 .. -w Iz.

Mellan de två periferiella spåren 17, 18 finns ett tredje periferiellt spår 22 vars bottendiameter är större än spårens 17, 18 bottendiameter. I detta spår 22 är monterad en stödring 23 vilken innefattar ett bandformigt 1agerparti 24 för glidkontakt med 7 cylindern 10 och en invändig fläns 25. Den senare upptas i det 'centrala periferiella spåret 22 på kolven ll, varigenom stödringen 23 fixeras axie11t relativt kolven 11.Between the two peripheral grooves 17, 18 there is a third peripheral groove 22 whose bottom diameter is larger than the bottom diameter of the grooves 17, 18. Mounted in this groove 22 is a support ring 23 which comprises a band-shaped bearing portion 24 for sliding contact with the cylinder 10 and an inner flange 25. The latter is received in the central peripheral groove 22 on the piston 11, whereby the support ring 23 is fixed axially relative to the piston 11.

Stödringens 23 bandformiga 1agerparti 24 sträcker sig axie11t ut över de båda ringelementen 19, 20 och pressas av dessa radiellt ut mot cylindern 10. “ Stödringen 23 fungerar alltså både som tätningsorgau och som radie11t lager mellan kolven 11 och cy1indern 10. Lagerfunktionen är i huvudsak koncentrerad ti11 stödringens 23 centrala del, ty denna Å de1 av ringen vilar direkt mot kolven 11 utan att understödjas av de eftergivliga ringelementen 19, 20. Tätningsfunktionen är â andra sidan koncentrerad till sidodelarna 24a, 24b hos det bandformiga stödpartiet 24, Dessa delar 24a, 24b hos ringen 23'pressas radíellt utåt och understöds av de eftergivïiga ringelementen 19, 20 i sin tätande anliggning mot cylindern 10. Sidopartierna 24a,-24b hos stödpartiet 24 är mycket tunna och uppvisar en tjocklek av ca 5/10 mm.= Stödringen 23 är lämpligen ti11verkad av ett tvärbundet ultrahögmolekylärt polyetenmaterial. Ett sådant material har mycket goda självsmörjande egenskaper och gör tätningsanordningen helt oberoende av alla slags smörjmedel. Mycket goda resultat har uppnåtts med ett material ka11at HDPEX som har utvecklats och marknadsförs av ASEA Compound. Stödringen 23 har formats av detta material genom formsprutning. Någon bearbetning efter formsprutningen är icke nödvändig vilket innebär att tillverkningskostnaderna kan hållas mycket låga.The band-shaped bearing portion 24 of the support ring 23 extends axially across the two ring elements 19, 20 and is pressed by these radially out towards the cylinder 10. The support ring 23 thus functions both as a sealing member and as a radial bearing between the piston 11 and the cylinder 10. The bearing function is mainly concentrated to the central part of the support ring 23, because this Å part1 of the ring rests directly against the piston 11 without being supported by the resilient ring elements 19, 20. The sealing function is on the other hand concentrated on the side parts 24a, 24b of the band-shaped support portion 24. These parts 24a, 24b of the ring 23 'is pressed radially outwards and is supported by the resilient ring elements 19, 20 in their sealing abutment against the cylinder 10. The side portions 24a, -24b of the support portion 24 are very thin and have a thickness of about 5/10 mm. = The support ring 23 is suitably made of a crosslinked ultra-high molecular weight polyethylene material. Such a material has very good self-lubricating properties and makes the sealing device completely independent of all kinds of lubricants. Very good results have been achieved with a material called HDPEX that has been developed and marketed by ASEA Compound. The support ring 23 has been formed of this material by injection molding. No machining after injection molding is necessary, which means that manufacturing costs can be kept very low.

Kolvtätningen enligt uppfinningen är mycket fördelaktig dels genom att den tunna stödringen.23 ger mycket goda friktionsegenskaper vid sin kontakt mot cylindern, och dels genom att de understödjande ag, 8403629-2 n 4 Ieftergdvïiga ringeïementen 19, 20 utgörs av konventíoneïïa tätningsringar som vid genomsïitage av stödringens fïankpartier 24a, 24b själva kan överta tätningsfunktionen hos koïvtätningen. I det ovan nämnda materialexempïet får stödringen en mycket låg friktionskoefficient och dessutom en mycket liten skillnad meïlan =g1id- och viïofriktion. rThe piston seal according to the invention is very advantageous partly in that the thin support ring.23 gives very good frictional properties on its contact with the cylinder, and partly in that the supporting rings, 8403629-2 n 4 Subsequent ring elements 19, 20 consist of conventional sealing rings which on passage of the flank portions 24a, 24b of the support ring themselves can take over the sealing function of the coefficient seal. In the above-mentioned material example, the support ring has a very low coefficient of friction and, moreover, a very small difference between mean and smooth friction. r

Claims

8403629-2 Patent claims.

Piston seal for a pneumatic piston-cylinder device (10,11) comprising two resilient and radially expandable ring elements (19,20) mounted on the piston (11) at a mutual axial distance and a support ring (23) abutting against the cylinder (10) is axially fixed in a peripheral groove in the piston (11) between the ring elements (19.20), characterized in that the support ring (23) has two opposite axially oriented thin-walled sealing walls (24ê-245) intended for sealing abutment (10) against the cylinder, Each sealing lips (24a, 12b) are arranged to extend axially past the two resilient ring elements (18, 20) during the operating conditions of the device and to be pressed by these radii outwards into the sealing abutment Å.

Coal seal according to claim 1, characterized in that the resilient ring elements (19,20) comprise U-shaped against the cylinder (10). standard type sealing rings. «1

Co-seal according to the patent claim 1 or 2, characterized in that the support ring (23) is made of a self-lubricating plastic material such as a cross-linked high molecular weight polyethylene.