DE1216611B - Externally ignited internal combustion engine - Google Patents

Description

Spark-ignition internal combustion engine The invention relates to a free-ignition internal combustion engine according to patent 1019 125, in which the combustion chamber is arranged in the piston and the ignition source is arranged in the cylinder head and in which a circular air movement is generated in the compression and combustion chamber. One or more fuel jets hit the combustion chamber wall in a closed jet shape with a short, free jet path length at an acute angle in such a way that the fuel injected in this way spreads on the combustion chamber wall as a thin film over a large surface, the combustion chamber wall being kept at a temperature, which is below the decomposition temperature of the fuel, but still in its boiling range. Furthermore, the time of fuel injection near the top dead center of the piston at the beginning of the suction stroke and / or the end of the compression stroke is selected so that the fuel adhering to the wall evaporates weakly until ignition, whereupon it becomes faster and faster after the flame front has formed Evaporation takes place.

In such a mixture formation process and combustion process, the risk of knocking is reduced to a minimum, since the mixture of fuel vapor and combustion air is always produced immediately before the moment when combustion begins. The mixture of evaporating fuel and combustion air is therefore only exposed to the influence of high pressure and high temperature for a very short time; in contrast, for example, to the gasoline engine, in which the mixture is compressed together and is available for a long time before it is burned. The consequence of this is that the compression ratio and thus the performance and economy of the engine are limited with the level of the octane number in Otto engines. In the mixture formation process and combustion process according to the main patent, there is no such restriction. The prerequisite here, however, is that reliable ignition is ensured with a low compression ratio that is predetermined for spark ignition. The ignition source provided in the subject of the main patent represents a useful means for this purpose. It must be taken into account, however, that when a spark plug is used, as is considered expedient in many cases, only one locally and spatially limited ignition spark is formed will. If the compression ratio is small, this can lead to difficulties under certain circumstances. In this case it cannot be determined with certainty that the mixture suitable for ignition is also present at the point of ignition spark formation.

To overcome these difficulties, the invention proposes that the combustion chamber wall in the direction of air rotation at the end or immediately behind the wall surface wetted by the fuel film-like in a known manner as locally limited, with a catalytic substance, for. B. sodium, platinum sponge od. Like. Affected. or lined, lined wall zone of increased reaction speed> C is formed. This forms the zone of the combustion chamber wall with the catalyst. a band extending transversely to the air or mixture flow, the width of which is preferably smaller than that which is wetted with fuel. Wall bend is.

It is known per se, combustion chambers of internal combustion engines to be lined with metal.

For example, there is thermal insulation in the cylinder of a known internal combustion engine provided, which consists of a porous, liquid-permeable metal layer. A hydraulic fluid is pumped into this lining from the outside. While running of the engine then forms on the liner surface exposed to the hot combustion gases a heat-insulating vapor skin.

Another known internal combustion engine has catalytic converters at suitable points within the combustion chamber, for example on the inner wall of the cylinder head or arranged on the piston crown. The catalysts form here the replacement of the liquid anti-knock agents added to the fuel in such a way that by Such a catalyst the rest of the at the spark ignition source (spark plug) is imperfect burned mixture can now burn definitively. So the catalyst has here only the task of eraänzuno, or the completion of the combustion process a mixture consisting of liquid fuel and air without this the ignition process at the spark plug itself is influenced.

Finally, the use of a catalytic converter in an injection internal combustion engine has become known, in which the liquid fuel is injected directly into the combustion air by-C Cre. Here, too, it is assumed that as a result. the only shortly before einaeleiteten Zündun- fuel injection, the mixing ades liquid fuel with the air and thus the ignition and the combustion process are themselves imperfect and therefore by special means - here catalysts - in turn should only be supplemented. The above-mentioned imperfect fuel-air mixture is attributed to the fact that, due to the inertia of the still liquid fuel droplets, they do not move quickly enough during the injection and combustion process, which takes place in a very short time, to the extent necessary for good combustion could mix the air, which led to poor combustion and gave rise to the aforementioned wall lining.

In the present additional invention, too, the concept of the catalytic wall lining for the purpose of influencing the engine combustion is assumed, but in application t2 b to the externally ignited internal combustion engine according to the main patent described above.

The measure according to the invention lies in. The case of the mixing of two media of the same state provided here, namely the mixing of evaporated fuel films with the combustion air, is not immediately obvious, since the inertia of the individual, now vaporous fuel particles plays no or only a subordinate role. If a catalytic wall lining and on top of that in a special way is proposed here, then this is based on considerations about the above-described, flat injection and mixture formation process and the peculiarity of the ignition source used. return. As a result of this zone-wise lining of the combustion chamber wall with a catalytic converter, the reaction speed of the fuel-vapor-air mixture is locally greatly increased and the ignition is initiated with certainty. This has a favorable especially during cold starting of the engine - off.

The invention is shown schematically in the drawing using an exemplary embodiment. -Hierbei Fig. 1 shows a section through the piston of a spark-ignition internal combustion engine having arranged therein the combustion chamber, wherein the injection nozzle is shown in perspective F i g. 2 a view of the piston crown and combustion chamber. of the piston of FIG. 1.

In the numbering, reference is made only to the parts essential for the invention. The combustion chamber 2, the diameter d of which is smaller than the cylinder diameter D , is arranged in the piston 1 of the internal combustion engine, which is not shown further. The selected combustion chamber 2 has a shape similar to a rotational body with a combustion chamber opening 2a, which is not constricted in the present example. However, the combustion chamber opening could just as well be constricted with respect to a widest cross-sectional area of the combustion chamber, which for example lies in a plane perpendicular to the piston axis, without thereby restricting the invention. 3 the injection "is edanke a, nozzle designated, from whose nozzle mouth, 3 a fuel jets 4, 5 (the number is only exemplary) are so applied in a known manner at acute angles of incidence on the combustion chamber wall, that the wall coated. Fuel to the combustion chamber wall surface spreads like a film, as indicated under 6, 7. Over the wall surface wetted by the fuel in a film-like manner, the combustion air is led away in a known manner in the sense of the air rotation indicated by the arrow 8 , this air rotation already at its entry is introduced in the indicated under 9 working cylinder. the, esehene upstream in a spark ignition internal combustion engine spark plug is indicated at 10. According to the invention the combustion chamber wall in the direction of air rotation is now indicated 8 at the end of the film-like wetted wall surface, such as below 11, or immediately after artery Wall surface 6, 7 which is wetted in a film-like manner by the fuel as locally admitted enzte, with a catalytic substance, e.g. B. sodium, platinum sponge or the like., Coated or lined wall zone 11, 12 formed of increased reaction speed, via which the fuel-vapor-air mixture is carried away immediately after its formation in the direction of the air rotation 8 , the catalyst- affected combustion chamber wall zone 11, 12 forms a strip extending transversely to the air or mixture flow, the width b, b of which is preferably smaller than the fuel-wetted wall bend cc.

Claims (2)

Claims: 1. Spark-ignition internal combustion engine, in which the combustion chamber is arranged in the piston and the ignition source in the cylinder head and in which a circular air movement is generated in the compression and combustion chamber, with one or more fuel jets in a closed jet shape with a short, free jet path length impinge on the combustion chamber wall at an acute angle in such a way that the fuel injected in this way spreads on the combustion chamber wall as a thin film over a large surface, the combustion chamber wall being kept at a temperature below the decomposition temperature of the fuel, but still in its boiling range is, and furthermore the time of the fuel injection in the vicinity of the top dead center of the piston at the beginning of the suction stroke and / or at the end of the compression stroke is selected so that the fuel adhering to the wall evaporates weakly until ignition, after which the flames burst front always s occurs chneller expectant evaporation according to Patent 1019125, characterized denotes Ge, that to ensure the ignition of the combustion chamber wall in the direction of air rotation (8) at the end of or immediately behind the film-like wetted by the K-raftstoff wall surface (6, 7) in a manner known per Way as a localized, with a catalytic substance, e.g. B. sodium, Platinschwanini od. The like. Affected or lined wall zone (11, 12) of increased reaction rate is formed. 2. Externally ignited internal combustion engine according to claim 1, characterized in that the catalyst- affected combustion chamber wall zone (11, 12) forms a band extending transversely to the air or mixture flow, the width (b, b) of which is preferably smaller than the fuel-wetted wall arch (cc) is. Considered publications: German Patent Nos. 489 034, 191 694; U.S. Patent No. 2,552,555.