SE468222B

SE468222B - Two-stroke internal combustion engine with a regulated exhaust port

Info

Publication number: SE468222B
Application number: SE9100968A
Authority: SE
Inventors: F A G Doeragrip
Original assignee: Electrolux Ab
Priority date: 1991-04-03
Filing date: 1991-04-03
Publication date: 1992-11-23
Also published as: SE9100968D0; SE9100968L

Abstract

The invention relates to a two-stroke internal combustion engine in which the piston, by rotation about its centre axis 23, before the bottom dead centre, has an exhaust valve function. This is brought about by rollers 24 running against cams 25. These can be placed in the cylinder and, respectively, in the piston or vice versa. The valve functions are brought about by a raised cam 31 positioned on the upper part of the piston opening and, respectively, closing the exhaust port 20 in the cylinder when the piston rotates. <IMAGE>

Description

-Ië- Cm CO 222 och en vevstake 15. I cylinderväggen mynnar ett avgasrör 16, överströmska- naler17, 18 och en inloppskanal 19. Mynningarna eller portarna för avgas 20 respektive förbränningsgas 21, 22 är belägna ovanför kolven (fig. 3) medan in- loppsmynningen friläggs när kolven passerar det övre vändläget. Detta är den vanliga principen för en tvåtaktsmotor med vevhusspolning. -Ië- Cm CO 222 and a connecting rod 15. In the cylinder wall opens an exhaust pipe 16, overcurrent channels 17, 18 and an inlet duct 19. The mouths or ports for exhaust 20 respectively combustion gas 21, 22 are located above the piston (Fig. 3) while the mouthpiece is exposed when the piston passes the upper turning position. This is it common principle for a two-stroke engine with crankcase winding.

Det som gör motorn på ritningen skiljaktig från den vanliga konventionella är en anordning för vridning av kolven runt dess centrumaxe123. I väggen av vardera överströmskanalen finns en styrrulle 24 som samverkar med en utskuren, rombisk kurva 25 i kolvens mantelyta. Kurvan har två motstånde sidor 26, 27 parallella med axeln 23 och två snedställa sidor 28, 29, varmed bildas en romboid i kolven. Vidare är kolvens lagring mot vevstaken ett sfäriskt rullager 30 som tillåter en begränsad vridning av kolven relativt vevstaken. Kolvens ovansida uppvisar en uppdragen kant 31 i närheten av avgasporten 20. En motor med denna avgasanordning har följande verkningssätt: När kolven i fig. l är nedåtgående under expansionstakten börjar den öppna avgasporten 20 och vridning inträffar då rullen 24 går in på sidan 28 av kurvan 25. Avgaser strömmar under tiden ut genom röret 16. Då kolven når det nedre vändläget har den vridit sig som figurerna 3 och 5 visar, dvs. kanten 31 ställs för porten 20 så att avgasströmmen därvid stryps. Den inkommande för- bränningsgasen från kanalerna 17, 18 kvarstannar i förbränningsrummet och komprimeras, när kolven vänder uppåt. Någon vridning av kolven förekommer inte så länge rullen 24 följer sidan 26 av kurvan 25, men strax före övre vänd- läget vrides kolven i motsatt riktning till föregående, då rullen följer sidan 29 av kurvan 25. Under nästföljande expansionstakt behåller den detta vinkelläge, eftersom rullen då följer sidan 27 i kurvan 25. Före kolvens nedre vändläge följer rullen ånyo sidan 28, varvid kanten 31 ställs för porten 20 såsom förut beskrivits. Förloppet upprepas under varje motorvarv.What makes the engine in the drawing different from the usual conventional is a device for rotating the piston about its center axis123. In the wall of each overcurrent channel has a guide roller 24 which cooperates with a cut-out, rhombic curve 25 in the mantle surface of the piston. The curve has two opposite sides 26, 27 parallel to the shaft 23 and two inclined sides 28, 29, thereby forming a rhomboid in the flask. Furthermore, the bearing of the piston against the connecting rod is a spherical roller bearing 30 which allows a limited rotation of the piston relative to the connecting rod. Top of piston has a raised edge 31 in the vicinity of the exhaust port 20. An engine with this exhaust device has the following mode of action: When the piston of Fig. 1 is downward during the rate of expansion, it begins to open the exhaust port 20 and rotation occurs when the roller 24 enters the side 28 of curve 25. Exhaust gases meanwhile flow out through the pipe 16. When the piston reaches the lower turning position, it has turned as Figures 3 and 5 show, i.e. edges 31 is set for the port 20 so that the exhaust gas flow is thereby restricted. The incoming the combustion gas from the ducts 17, 18 remains in the combustion chamber and compressed, with the piston facing upwards. There is some twisting of the piston not so long as the roller 24 follows the side 26 of the curve 25, but just before the upper turning position, turn the piston in the opposite direction to the previous one, as the roller follows page 29 of curve 25. During the next rate of expansion it maintains this angular position, since the roller then follows side 27 of the curve 25. Before the lower turning position of the piston the roller again follows the side 28, the edge 31 being set for the gate 20 as before described. The process is repeated during each engine revolution.

Det beskrivna utförandet är ett exempel på hur anordningen skall fungera.The described embodiment is an example of how the device should work.

Givetvis finns andra utföranden som fungerar lika bra som denna. Exempelvis kan styrrullen och kurvan byta plats, så att rullen följer med i kolvens rörelse.Of course, there are other designs that work just as well as this one. For example the guide roller and the curve can change places, so that the roller follows the movement of the piston.

Denna kan exempelvis var fjäderstyrd i ena riktningen men tvångsstyrd i den andra. Förutom reglering av avgasutsläppet med denna anordning kan även insugstiderna till vevhuset regleras med denna anordning, exempelvis genom en speciell utformning av kolvskörtet.This can, for example, be spring-controlled in one direction but forcibly controlled in it Other. In addition to regulating exhaust emissions with this device can also the suction times to the crankcase are regulated with this device, for example by a special design of the piston skirt.

Claims

3,468,222 Claims

l. Two-stroke internal combustion engine with a regulated exhaust port in the cylinder wall and overcurrent ducts to the combustion chamber from the crankcase and intake port in the cylinder wall, which ports and ducts are opened and closed by the reciprocating movement of the piston in the cylinder, characterized in a top with a raised edge (31) in the vicinity of the exhaust port (20) and a rotating device (24, 25) for rotating the piston about its center axis (23) and a spherical (gimbal) piston bolt bearing (30) 'against the connecting rod.

Two-stroke internal combustion engine according to claim 1, characterized in that the turning device is of the type curve (25) and curve follower (24), of which the curve is a closed cam in itself and the curve follower a roller and one of the two sits in the cylinder and the others on lltolvèn.

A two-stroke internal combustion engine according to claim 2, characterized in that the curve comprises two separate cam parts (28, 29) inclined relative to the center axis (23) of the piston, and that one part (28) when in contact with the window rotates the piston, so that its raised edge covers the exhaust port, and that the second curve part (29) rotates the piston back.

4. A two-stroke internal combustion engine according to claim 2, characterized in that the curve is doubled with a cut-out rhombic recess forming said cam in the circumferential surface of the piston near one of the overflow channels and a hcadant recess at a second overflow canal located on the carbon side of the piston.

5. The interior of the cylinder has cam surfaces in two diametrically opposite sides of the cylinder, which cam surfaces form double curves in said turning device, and that rollers for co-operation with the curves are arranged on two diametrically opposite sides.