EP0302045B2 - Two-stroke engine - Google Patents

Two-stroke engine Download PDF

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Publication number
EP0302045B2
EP0302045B2 EP19880890184 EP88890184A EP0302045B2 EP 0302045 B2 EP0302045 B2 EP 0302045B2 EP 19880890184 EP19880890184 EP 19880890184 EP 88890184 A EP88890184 A EP 88890184A EP 0302045 B2 EP0302045 B2 EP 0302045B2
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EP
European Patent Office
Prior art keywords
piston
injection
nozzle
fuel
internal combustion
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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.)
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EP19880890184
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German (de)
French (fr)
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EP0302045A2 (en
EP0302045A3 (en
EP0302045B1 (en
Inventor
Diethard Dipl.-Ing. Plohberger
Leopold Dr. Mikulic
Klaus Dr. Landfahrer
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AVL List GmbH
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AVL List GmbH
AVL Gesellschaft fuer Verbrennungskraftmaschinen und Messtechnik mbH
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M69/00—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel
    • F02M69/04—Injectors peculiar thereto
    • F02M69/042—Positioning of injectors with respect to engine, e.g. in the air intake conduit
    • F02M69/045—Positioning of injectors with respect to engine, e.g. in the air intake conduit for injecting into the combustion chamber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B75/00—Other engines
    • F02B75/02—Engines characterised by their cycles, e.g. six-stroke
    • F02B2075/022—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle
    • F02B2075/025—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle two

Definitions

  • the invention relates to a two-stroke internal combustion engine with crankcase flushing with an overflow channel, the overflow opening in the cylinder is controlled by the engine piston, the bottom of which is flat and rotationally symmetrical, and with a fuel injection nozzle opposite the outlet opening in the overflow channel, the injection jet of the injection nozzle is directed to the side of the piston head facing the cylinder chamber and the jet axis of the injection jet forms an angle with the piston axis which is less than 90, the injection jet of the injection nozzle being directed at least predominantly towards the half of the piston head opposite the outlet opening.
  • FIG. 25 shows a two-stroke internal combustion engine of the type mentioned, in which the injection jet of the injection nozzle is directed towards the half opposite the outlet opening. This creates an air flow directed against the fuel, which prevents the direct outflow of the mixture through the open outlet and reduces the fuel losses.
  • the possible power yield is limited by the injection and evaporation time of the fuel, which means that the measures mentioned in the high speed range and high performance requirements alone cannot achieve a satisfactory reduction in fuel losses.
  • a partial improvement of the mixture preparation is achieved by the teaching from GB-A 723 972, where in a two-stroke internal combustion engine of the type mentioned at the outset, the injection jet of the injection nozzle is directed toward the side of the piston head facing the cylinder chamber.
  • the jet axis of the injection jet closes with the Piston axis an angle less than 90.
  • fuel losses due to outflow through the outlet opening cannot be prevented by this.
  • the aim of the invention is to avoid the disadvantages mentioned and to propose a two-stroke internal combustion engine of the type mentioned at the outset, which is distinguished by a simple structure and only very low fuel losses and hydrocarbon emissions, these advantages being retained even at higher engine speeds and loads should.
  • the injection nozzle is designed as a multi-hole nozzle, preferably as a two-jet nozzle, and that for the area of higher engine speeds and loads, the start of injection is defined even before the overflow opening of the overflow channel is opened by the piston, so that part of the fuel in the overflow channel pre-evaporates can.
  • the fuel is injected during the purging phase at a time when the overflow channel and outlet channel are open. The fuel evaporates rapidly on the side of the piston head facing the cylinder chamber.
  • the air movement that occurs during the purging of the cylinder leads on the one hand to a very good mixture formation and, on the other hand, to surprisingly low fuel losses, because due to the at least predominant injection onto the half of the piston head opposite the outlet opening, there is an air flow that opposes the fuel jet and prevents the outflow of mixture forms a kind of barrier through the simultaneously opened outlet.
  • the measures according to the invention result in the advantage of good cooling of the piston crown by the injected fuel, which also removes the heat of vaporization required for the evaporation.
  • the multi-jet fuel injection distributes the fuel better, which leads to faster evaporation and more uniform cooling of the piston crown. This makes it possible to increase the performance of the internal combustion engine with the same dimensions without resulting in an increased fuel loss.
  • each jet axis of the injection jets viewed in a top view of the piston, is directed essentially towards one of the overflow channels additionally arranged on the circumference of the cylinder wall.
  • FIG. 1 shows a two-stroke internal combustion engine according to the invention in longitudinal section, in which a plurality of channels 2, 2 ', which are distributed on the circumference of the cylinder wall 9, open into overflow openings 12, 12' in the cylinder chamber 1, to which an outlet channel 3 with an outlet opening 13 is assigned, which extends over a larger part of the height of the cylinder space 1 than the overflow openings 12, 12 'and is therefore released earlier by the piston 4 when the piston 4 moves in the direction of the crankcase, not shown, in order to allow the combustion gases to flow out before the opening of the To allow overflow openings.
  • An injection nozzle 5 is arranged in one of the overflow channels 2, the injection jet 7 of which is directed against the side 8 of the piston head 6 facing the cylinder space 1.
  • the beam axis 7 ' encloses an angle a which is less than 90 with the piston movement directed parallel to the bottom dead center and the piston axis 10.
  • the fuel is largely injected at a point in time when the piston 4 is in the region of its bottom dead center and the overflow openings 12, 12 'are therefore open. If the duration of the injection exceeds the opening duration of the overflow channels, as can be the case at very high speeds, it is possible and provided with the arrangement described to shift the start of injection in the "earlier" direction so that part of the fuel in the overflow channel 2 or 2 'can pre-evaporate, which also results in a very good mixture formation. As a result, the two-stroke internal combustion engine described is also suitable for very high speeds of up to over 10,000 revolutions per minute, without loss of performance or increased fuel consumption due to insufficient mixture formation or increased fuel losses.
  • FIG. 2 shows a variant of a two-stroke internal combustion engine according to the invention with a plurality of injection nozzles 5 arranged in overflow channels 2, 2 '.
  • the jet axes 7' of the injection jets 7 of this injection nozzle cross each other in a manner offset from the center 11 of the piston 4 in the direction of the overflow channel 2 Point.
  • the injection direction of the nozzle arranged in the overflow channel 2 ' is essentially opposite to the inflow direction of the scavenging air of the opposite overflow channels 2'. This leads to a correspondingly strong swirling of the purge air with the vaporized fuel, which results in good mixture preparation and control of the charge stratification. In addition, this also reduces the loss of fuel via the outlet duct 3 and thus also reduces the hydrocarbon emission.
  • FIG. 3 shows a further variant of a two-stroke internal combustion engine according to the invention, in which a two-jet nozzle 5 'is arranged in the overflow channel 2 or in the direction of the area of the cylinder chamber 1 directly adjoining it.
  • the jet axes 7 'of the injection jets 7 of this nozzle are essentially directed against the purge air flows entering the cylinder space 1 from two different overflow channels 2'. This ensures particularly good swirling and thus mixture preparation. At the same time, the fuel losses caused by an outflow of fuel mixture into the outlet channel 3 are minimized.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combustion Methods Of Internal-Combustion Engines (AREA)
  • Fuel-Injection Apparatus (AREA)

Description

Die Erfindung bezieht sich auf eine Zweitakt-Brennkraftmaschine mit Kurbelgehäusespülung mit einem Überströmkanal, dessen Überströmöffnung in den Zylinder vom Motorkolben gesteuert wird, dessen Boden flach und rotationssymmetrisch ausgebildet ist, sowie mit einer der Auslaßöffnung gegenüberliegenden Kraftstoff-Einspritzdüse im Überströmkanal, wobei der Einspritzstrahl der Einspritzdüse auf die dem Zylinderraum zugewandte Seite des Kolbenbodens gerichtet ist und die Strahlachse des Einspritzstrahls mit der Kolbenachse einen Winkel einschließt, der kleiner als 90 ist, wobei der Einspritzstrahl der Einspritzdüse zumindest überwiegend auf die der Auslaßöffnung gegenüberliegende Hälfte des Kolbenbodens gerichtet ist.The invention relates to a two-stroke internal combustion engine with crankcase flushing with an overflow channel, the overflow opening in the cylinder is controlled by the engine piston, the bottom of which is flat and rotationally symmetrical, and with a fuel injection nozzle opposite the outlet opening in the overflow channel, the injection jet of the injection nozzle is directed to the side of the piston head facing the cylinder chamber and the jet axis of the injection jet forms an angle with the piston axis which is less than 90, the injection jet of the injection nozzle being directed at least predominantly towards the half of the piston head opposite the outlet opening.

In "INGENIEURS DE L'AUTOMOBILE" 11-77, Seite 729, wird in Fig. 25 eine Zweitakt-Brennkraftmaschine der genannten Art gezeigt, bei der der Einspritzstrahl der Einspritzdüse auf die der Auslaßöffnung gegenüberliegende Hälfte gerichtet ist. Dadurch wird eine dem Kraftstoff entgegengerichtete Luftströmung erzeugt, welche das direkte Ausströmen des Gemisches durch den geöffneten Auslaß unterbindet und die Kraftstoffverluste vermindert. Besonders im hohen Drehzahl- und Lastbereich wird die mögliche Leistungsausbeute durch die Einspritz- und Verdampfungszeit des Kraftstoffes begrenzt, wodurch allein mit den genannten Maßnahmen im hohen Drehzahlbereich bei hohen Leistungsanforderungen keine zufriedenstellende Reduzierung der Kraftstoffverluste zu erreichen ist.In "INGENIEURS DE L'AUTOMOBILE" 11-77, page 729, FIG. 25 shows a two-stroke internal combustion engine of the type mentioned, in which the injection jet of the injection nozzle is directed towards the half opposite the outlet opening. This creates an air flow directed against the fuel, which prevents the direct outflow of the mixture through the open outlet and reduces the fuel losses. Particularly in the high speed and load range, the possible power yield is limited by the injection and evaporation time of the fuel, which means that the measures mentioned in the high speed range and high performance requirements alone cannot achieve a satisfactory reduction in fuel losses.

Aus der EP-A1 223 767 wurde eine Zweitakt-Brennkraftmaschine bekannt, bei welcher der Einspritzstrahl von der Kurbelgehäuseseite her in das Innere des hohlen Kolbens gerichtet ist. Dabei trifft bei der Kolbenbewegung zum Kurbelgehäuse hin ein Teil des Kraftstoffes auf die zum Kurbelgehäuse gerichtete Seite des Kolbenbodens auf. Damit laßt sich zwar eine relativ gute Gemischaufbereitung erreichen, doch muß in Kauf genommen weiden, daß ein beträchtlicher Teil des aufbereiteten Gemisches beim Spülen unverbrannt in den Auslaßkanal gelangt und damit verloren geht.From EP-A1 223 767 a two-stroke internal combustion engine was known, in which the injection jet is directed from the crankcase side into the interior of the hollow piston. During the piston movement towards the crankcase, part of the fuel hits the side of the piston head facing the crankcase. A relatively good mixture preparation can be achieved in this way, but it must be accepted that a considerable part of the prepared mixture reaches the outlet channel unburned during flushing and is therefore lost.

Eine teilweise Verbesserung der Gemischaufbereitung wird durch die Lehre aus der GB-A 723 972 erreicht, wo bei einer Zweitakt-Brennkraftmaschine der eingangs genannten Art der Einspritzstrahl der Einspritzdüse auf die dem Zylinderraum zugewandte Seite des Kolbenbodens gerichtet ist Die Strahlachse des Einspritzstrahles schließt dabei mit der Kolbenachse einen Winkel kleiner 90 ein. Kraftstoffverluste infolge Abströmung durch die Auslaßöffnung können dadurch jedoch nicht verhindert werden.A partial improvement of the mixture preparation is achieved by the teaching from GB-A 723 972, where in a two-stroke internal combustion engine of the type mentioned at the outset, the injection jet of the injection nozzle is directed toward the side of the piston head facing the cylinder chamber. The jet axis of the injection jet closes with the Piston axis an angle less than 90. However, fuel losses due to outflow through the outlet opening cannot be prevented by this.

Weiters ist es zur Minimierung von Kraftstoffverlusten aus der DE-B1 272 619 bekannt, den Kraftstoff auf die der Auslaßöffnung gegenüberliegende Hälfte des Kolbenbodens zu richten. In diesem Bereich des Kolbenbodens ist eine taschenförmige Verdampfungskammer angeordnet, in welcher die Tröpfchen des Kraftstoffstrahles an der heißen Wand der Verdampfungskammer vorverdampfen. Nachteilig ist hier die komplizierte Form des Zylinderbodens.Furthermore, in order to minimize fuel losses from DE-B1 272 619, it is known to direct the fuel onto the half of the piston head opposite the outlet opening. A pocket-shaped evaporation chamber is arranged in this area of the piston head, in which the droplets of the fuel jet pre-evaporate on the hot wall of the evaporation chamber. The disadvantage here is the complicated shape of the cylinder base.

Ziel der Erfindung ist es, die genannten Nachteile zu vermeiden und eine Zweitakt-Brennkraftmaschine der eingangs erwähnten Art vorzuschlagen, die sich durch einen einfachen Aufbau und nur sehr geringe Kraftstoffverluste und Kohlenwasserstoff-Emissionen auszeichnet, wobei diese Vorteile auch bei höheren Motordrehzahlen und Lasten beibehalten werden sollen.The aim of the invention is to avoid the disadvantages mentioned and to propose a two-stroke internal combustion engine of the type mentioned at the outset, which is distinguished by a simple structure and only very low fuel losses and hydrocarbon emissions, these advantages being retained even at higher engine speeds and loads should.

Erfindungsgemäß wird dies dadurch erreicht, daß die Einspritzdüse als Mehrlochdüse, vorzugsweise als Zweistrahldüse ausgebildet ist, und daß für den Bereich höherer Motordrehzahlen und Lasten der Einspritzbeginn schon vor Öffnen der Überströmöffnung des Überströmkanals durch den Kolben festgelegt ist, sodaß ein Teil des Kraftstoffes im Überströmkanal vorverdampfen kann. Dabei erfolgt die Kraftstoffeinspritzung während der Spülphase zu einem Zeitpunkt, zu dem Überströmkanal und Auslaßkanal offen sind. Der Kraftstoff verdampft rasch an der dem Zylinderraum zugewandten Seite des Kolbenbodens. Durch die während der Spülung des Zylinders vorhandene Luftbewegung kommt es einerseits zu einer sehr guten Gemischbildung und andererseits zu überraschend geringen Kraftstoffverlusten, weil durch das zumindest überwiegende Einspritzen auf die der Auslaßöffnung gegenüberliegende Hälfte des Kolbenbodens eine dem Kraftstoffstrahl entgegengerichtete Luftströmung vorhanden ist, welche gegen das Abströmen von Gemisch durch den gleichzeitig geöffneten Auslaß eine Art Barriere bildet.According to the invention, this is achieved in that the injection nozzle is designed as a multi-hole nozzle, preferably as a two-jet nozzle, and that for the area of higher engine speeds and loads, the start of injection is defined even before the overflow opening of the overflow channel is opened by the piston, so that part of the fuel in the overflow channel pre-evaporates can. The fuel is injected during the purging phase at a time when the overflow channel and outlet channel are open. The fuel evaporates rapidly on the side of the piston head facing the cylinder chamber. The air movement that occurs during the purging of the cylinder leads on the one hand to a very good mixture formation and, on the other hand, to surprisingly low fuel losses, because due to the at least predominant injection onto the half of the piston head opposite the outlet opening, there is an air flow that opposes the fuel jet and prevents the outflow of mixture forms a kind of barrier through the simultaneously opened outlet.

Weiters ergibt sich durch die erfindungsgemäßen Maßnahmen der Vorteil einer guten Kühlung des Kolbenbodens durch den eingespritzten Kraftstoff, der diesem auch die für die Verdampfung notwendige Verdampfungswärme entzieht. Durch die mehrstrahlige Einspritzung des Kraftstoffes wird dieser besser verteilt, was eine schnellere Verdampfung und eine gleichmäßigere Kühlung des Kolbenbodens bewirkt. Dadurch ist eine Leistungssteigerung der Brennkraftmaschine bei gleichbleibenden Abmessungen möglich, ohne daß sich dadurch ein erhöhter Kraftstoffverlust ergibt.Furthermore, the measures according to the invention result in the advantage of good cooling of the piston crown by the injected fuel, which also removes the heat of vaporization required for the evaporation. The multi-jet fuel injection distributes the fuel better, which leads to faster evaporation and more uniform cooling of the piston crown. This makes it possible to increase the performance of the internal combustion engine with the same dimensions without resulting in an increased fuel loss.

Außerdem ergibt sich dadurch eine verbesserte Möglichkeit der Steuerung der Ladungsschichtung im Zylinderraum.This also results in an improved possibility of controlling the charge stratification in the cylinder space.

Im Rahmen der Erfindung ist es vorteilhaft, wenn in zusätzlich am Umfang der Zylinderwand angeordneten Überströmkanälen weitere Einspritzdüsen vorgesehen sind. Deren Achsen können, in Draufsicht auf den Kolben gesehen, im wesentlichen entsprechend der Richtung der an den Zylinderraum unmittelbar anschließenden Teile der Überströmkanäle verlaufen.In the context of the invention, it is advantageous if additional injection nozzles are provided in overflow channels additionally arranged on the circumference of the cylinder wall. Their axes can, in Seen top view of the piston, run essentially according to the direction of the parts of the overflow channels directly adjoining the cylinder space.

Eine Weiterbildung der Erfindung sieht vor, daß jede Strahlachse der Einspritzstrahlen, in Draufsicht auf den Kolben gesehen, im wesentlichen auf einen der zusätzlich am Umfang der Zylinderwand angeordneten Überströmkanäle gerichtet ist. Durch diese Maßnahmen ist sichergestellt, daß die Einspritzstrahlen Komponenten des Spülluftstromes entgegengerichtet sind, wodurch einerseits die Verwirbelung des entstehenden Kraftstoffdampfes mit der Spülluft verbessert und anderseits ein Mitreißen des entsprechenden Kraftstoffgemisches in den Auslaßkanal weiter vermindert wird.A further development of the invention provides that each jet axis of the injection jets, viewed in a top view of the piston, is directed essentially towards one of the overflow channels additionally arranged on the circumference of the cylinder wall. These measures ensure that the injection jets components of the scavenging air flow are opposite, which on the one hand improves the swirling of the fuel vapor formed with the scavenging air and on the other hand further reduces the entrainment of the corresponding fuel mixture into the outlet duct.

Die Erfindung wird nun anhand der Zeichnung näher erläutert. Dabei zeigen:

  • Fig. 1 schematisch einen Längsschnitt durch eine erfindungsgemäße Zweitakt-Brennkraftmaschine,
  • Fig. 2 und 3 verschiedene Ausführungsvarianten einer erfindungsgemäßen Zweitakt-Brennkraftmaschine im Querschnitt.
The invention will now be explained in more detail with reference to the drawing. Show:
  • 1 schematically shows a longitudinal section through a two-stroke internal combustion engine according to the invention,
  • 2 and 3 different embodiment variants of a two-stroke internal combustion engine according to the invention in cross section.

Fig. 1 zeigt eine erfindungsgemäße Zweitakt-Brennkraftmaschine im Längsschnitt, bei der in den Zylinderraum 1 mehrere, am Umfang der Zylinderwand 9 verteilte Kanäle 2, 2' in Überströmöffnungen 12, 12' münden, denen ein Auslaßkanal 3 mit einer Auslaßöffnung 13 zugeordnet ist, der sich über einen größeren Teil der Höhe des zylinderraumes 1 als die Überströmöffnungen 12, 12' erstreckt und daher bei einer Bewegung des Kolbens 4 in Richtung auf das nicht dargestellte Kurbelgehäuse früher vom Kolben 4 freigegeben wird, um ein Abströmen der Verbrennungsgase vor dem Öffnen der Überströmöffnungen zu ermöglichen.1 shows a two-stroke internal combustion engine according to the invention in longitudinal section, in which a plurality of channels 2, 2 ', which are distributed on the circumference of the cylinder wall 9, open into overflow openings 12, 12' in the cylinder chamber 1, to which an outlet channel 3 with an outlet opening 13 is assigned, which extends over a larger part of the height of the cylinder space 1 than the overflow openings 12, 12 'and is therefore released earlier by the piston 4 when the piston 4 moves in the direction of the crankcase, not shown, in order to allow the combustion gases to flow out before the opening of the To allow overflow openings.

In einem der Überströmkanäle 2 ist eine Einspritzdüse 5 angeordnet, deren Einspritzstrahl 7 gegen die dem Zylinderraum 1 zugewandte Seite 8 des Kolbenbodens 6 gerichtet ist. Die Strahlachse 7' schließt dabei mit der zur Kolbenachse 10 parallelen zum unteren Totpunkt gerichteten Kolbenbewegung einen Winkel a ein, der kleiner als 90 ist.An injection nozzle 5 is arranged in one of the overflow channels 2, the injection jet 7 of which is directed against the side 8 of the piston head 6 facing the cylinder space 1. The beam axis 7 'encloses an angle a which is less than 90 with the piston movement directed parallel to the bottom dead center and the piston axis 10.

Wie in Fig. 1 angedeutet ist, erfolgt die Einspritzung des Kraftstoffes zum Großteil zu einem Zeitpunkt, zu dem sich der Kolben 4 im Bereich seines unteren Totpunktes befindet und die Überströmöffnungen 12, 12' daher offen sind. Wenn die Dauer der Einspritzung die Öffnungsdauer der Überströmkanäle übersteigt, wie das bei sehr hohen Drehzahlen der Fall sein kann, ist es mit der beschriebenen Anordnung möglich und vorgesehen, den Einspritzbeginn in Richtung "früher" so zu verschieben, daß ein Teil des Kraftstoffes im Überströmkanal 2 bzw. 2' vorverdampfen kann, wodurch sich ebenfalls eine sehr gute Gemischbildung ergibt. Dadurch eignet sich die beschriebene Zweitakt-Brennkraftmaschine auch für sehr hohe Drehzahlen bis über 10 000 Umdrehungen pro Minute, ohne daß ein Leistungsverlust oder erhöhter Kraftstoffverbrauch durch mangelnde Gemischbildung oder erhöhte Kraftstoffverluste auftreten kann.As indicated in FIG. 1, the fuel is largely injected at a point in time when the piston 4 is in the region of its bottom dead center and the overflow openings 12, 12 'are therefore open. If the duration of the injection exceeds the opening duration of the overflow channels, as can be the case at very high speeds, it is possible and provided with the arrangement described to shift the start of injection in the "earlier" direction so that part of the fuel in the overflow channel 2 or 2 'can pre-evaporate, which also results in a very good mixture formation. As a result, the two-stroke internal combustion engine described is also suitable for very high speeds of up to over 10,000 revolutions per minute, without loss of performance or increased fuel consumption due to insufficient mixture formation or increased fuel losses.

Durch das Auftreffen von relativ kühlem Kraftstoff auf den Kolbenboden 6 und dessen Verdampfung ergibt sich ein beträchtlicher Kühleffekt für den Kolbenboden 6, sodaß dieser einerseits dünner ausgeführt werden kann und anderseits eine entsprechende Leistungssteigerung aufgrund der verminderten Wärmedehnung des Kolbenoberteils möglich ist.The impact of relatively cool fuel on the piston crown 6 and its evaporation results in a considerable cooling effect for the piston crown 6, so that it can be made thinner on the one hand and a corresponding increase in performance is possible due to the reduced thermal expansion of the piston upper part.

Fig. 2 zeigt eine Variante einer erfindungsgemäßen Zweitakt-Brennkraftmaschine mit mehreren in Überströmkanälen 2, 2' angeordneten Einspritzdüsen 5. Die Strahlachsen 7' der Einspritzstrahlen 7 dieser Einspritzdüse kreuzen einander in einem deutlich vom Mittelpunkt 11 des Kolbens 4 in Richtung zum Überströmkanal 2 hin versetzten Punkt. Dabei ist die Einspritzrichtung der im Überströmkanal 2' angeordneten Düse im wesentlichen der Einströmrichtung der Spülluft der gegenüberliegenden Überströmkanäle 2' entgegengerichtet. Dies führt zu einer entsprechend starken Verwirbelung der Spülluft mit dem verdampften Kraftstoff, wodurch sich eine gute Gemischaufbereitung und Steuerung der Ladungsschichtung ergibt. Außerdem wird dadurch auch ein Verlust von Kraftstoff über den Auslaßkanal 3 verringert und damit auch eine Verringerung der Kohlenwasserstoff-Emission erreicht.FIG. 2 shows a variant of a two-stroke internal combustion engine according to the invention with a plurality of injection nozzles 5 arranged in overflow channels 2, 2 '. The jet axes 7' of the injection jets 7 of this injection nozzle cross each other in a manner offset from the center 11 of the piston 4 in the direction of the overflow channel 2 Point. The injection direction of the nozzle arranged in the overflow channel 2 'is essentially opposite to the inflow direction of the scavenging air of the opposite overflow channels 2'. This leads to a correspondingly strong swirling of the purge air with the vaporized fuel, which results in good mixture preparation and control of the charge stratification. In addition, this also reduces the loss of fuel via the outlet duct 3 and thus also reduces the hydrocarbon emission.

Fig. 3 zeigt eine weitere Variante einer erfindungsgemäßen Zweitakt-Brennkraftmaschine, bei der im Überströmkanal 2, bzw. in Richtung des an den Zylinderraum 1 unmittelbar anschließenden Bereiches eines solchen, eine Zweistrahldüse 5' angeordnet ist. Dabei sind die Strahlachsen 7' der Einspritzstrahlen 7 dieser Düse im wesentlichen den aus zwei verschiedenen Überströmkanälen 2' in den Zylinderraum 1 eintretenden Spülluftströmen entgegengerichtet. Dadurch wird eine besonders gute Verwirbelung und damit Gemischaufbereitung sichergestellt. Gleichzeitig werden die durch ein Abströmen von Kraftstoffgemisch in den Auslaßkanal 3 bedingten Kraftstoffverluste minimiert.FIG. 3 shows a further variant of a two-stroke internal combustion engine according to the invention, in which a two-jet nozzle 5 'is arranged in the overflow channel 2 or in the direction of the area of the cylinder chamber 1 directly adjoining it. The jet axes 7 'of the injection jets 7 of this nozzle are essentially directed against the purge air flows entering the cylinder space 1 from two different overflow channels 2'. This ensures particularly good swirling and thus mixture preparation. At the same time, the fuel losses caused by an outflow of fuel mixture into the outlet channel 3 are minimized.

Claims (3)

1. Two-stroke internal combustion engine with crankcase scavenging with a transfer passage (2) of which the transfer port (12) in the cylinder (1) is controlled by the piston (4) of which the crown (8) is made smooth and rotationally symmetrical, and with a fuel injection nozzle (5) lying in the transfer passage (2) opposite the exhaust port (13), the injection stream (7) from the nozzle (5) being directed at that face (8) of the piston crown (4) which is towards the combustion chamber (1), the axis (7') of the injected stream (7) making an included angle (a) with the axis (10) of the piston which is less than 90 °, and the injected stream (7) from the nozzle (5) is directed at least predominantly towards that half of the piston crown which lies opposite the exhaust port (13), characterised in that the injection nozzle is in the form of a multi-holed nozzle, preferably a two-stream nozzle (5'), and that in the upper ranges of engine speeds and loads the start of the injection is timed to occur before the transfer port (12) from the transfer passage (2) is uncovered by the piston (4), so that part of the fuel can pre-vaporise in the transfer passage (2).
2. Two-stroke internal combustion engine according to claim 1, characterised in that further injection nozzles (5) are provided in additional transfer passages (2') arranged at the periphery of the cylinder wall (9).
3. Two-stroke internal combustion engine according to claim 1 or 2, characterised in that each axis (7') of the injected streams (7), looking at the piston (4) in plan view, is directed substantially towards one of the additional transfer passages (2') arranged at the periphery of the cylinder wall (9).
EP19880890184 1987-07-30 1988-07-11 Two-stroke engine Expired - Lifetime EP0302045B2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT1937/87 1987-07-30
AT193787A AT397695B (en) 1987-07-30 1987-07-30 TWO-STROKE INTERNAL COMBUSTION ENGINE

Publications (4)

Publication Number Publication Date
EP0302045A2 EP0302045A2 (en) 1989-02-01
EP0302045A3 EP0302045A3 (en) 1990-01-17
EP0302045B1 EP0302045B1 (en) 1992-03-04
EP0302045B2 true EP0302045B2 (en) 1994-11-17

Family

ID=3524251

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19880890184 Expired - Lifetime EP0302045B2 (en) 1987-07-30 1988-07-11 Two-stroke engine

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Country Link
EP (1) EP0302045B2 (en)
JP (1) JPH0737765B2 (en)
AT (1) AT397695B (en)
DE (1) DE3868760D1 (en)

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Also Published As

Publication number Publication date
EP0302045A2 (en) 1989-02-01
ATA193787A (en) 1993-10-15
AT397695B (en) 1994-06-27
JPH0737765B2 (en) 1995-04-26
JPS6473167A (en) 1989-03-17
EP0302045A3 (en) 1990-01-17
DE3868760D1 (en) 1992-04-09
EP0302045B1 (en) 1992-03-04

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