Abstract:
An air-compressing internal combustion engine with oblique injection into an antechamber having a sphere-like combustion space and conduit of arranged offset relative to one another. A spheroid impact head with a cup shaped recess on the underside thereof facing the conduit is provided in the lower half of the combustion space. A glow plug is arranged in the downward current of the air flow downstream of the injection nozzle in the antechamber.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     The invention relates to an air-compressing self igniting internal combustion engine, with a main combustion space and an insert adjoining the latter, accommodated in the cylinder head and having an antechamber which comprises a sphere-like combustion space and a conduit. 
     An insert provided for air-compressing internal combustion engines and featuring an antechamber and oblique injection is disclosed in &#34;Technischer Rundschau&#34;, 25/90 page 37. In that device, the insert has, in the combustion space, in the region of the mouth of the conduit, an insertion pin with a spherical impact head, the underside of which is set obliquely to produce a moderate air turbulence. The glow plug protruding into the combustion space of the antechamber is arranged in the downward current, that is, downstream of the injection nozzle. Approximately half of the injection spray strikes the upper side of the impact head. 
     A high standard has already been achieved with such measures on the insert as regards fuel consumption, exhaust-gas and noise behavior. 
     It is the underlying object of the invention to reduce further the pollutant content in the exhaust gas by special measures on the antechamber side. 
     This and other objects and advantages are achieved according to the invention by the eccentricity of the conduit relative to the sphere-like combustion space and the special arrangement of the insertion pin with a pronounced positional offset relative to the conduit, which results in a substantially larger main inflow cross-section and a correspondingly smaller inflow cross-section of the air, and thus in more intensive mixing of the air with the fuel. This arrangement also reduces considerably the content of carbon monoxides and hydrocarbons and of particles in the engine exhaust gas, and meets all engine-specific requirements, e.g. with respect to naturally aspirated or supercharged engines and large- and small-volume engines. 
     Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-section of an internal combustion engine with the insert in the cylinder head and having an injection nozzle; and 
     FIGS. 2-5 depict the combustion space of the antechamber--viewed from above--showing various positions of the conduit and insertion pin and various arrangements of the glow plug and or the injection nozzle, indicated by an arrow. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a partial cut-out of an air-compressing internal combustion engine I with an insert 3, inserted obliquely in the cylinder head 2, and an injection nozzle 4. The insert 3 with its centrally adjoining insert neck 5 contains an antechamber which comprises a sphere-like combustion space 6 and a conduit 7 which is arranged eccentrically in the insert neck 5 and connects the combustion space 6 with the main combustion space 8 of the internal combustion engine 1 via burner openings 9 arranged in a star shape. The elongate combustion space 6 is formed by a cylindrical portion 6a and hemispheres 6b, 6c adjoining on both sides. 
     The longitudinal axis a of the conduit 7 is offset relative to the longitudinal axis b of the insert 3 by a distance of 0.25 to 1.25 mm and the longitudinal axis c of the injection nozzle 4 is arranged obliquely to the longitudinal axis b of the insert 3, the angle α of obliquity corresponding to about 5°. The latter can be between 2° and 10°. The injection nozzle 4 is situated opposite the conduit 7 in such a way that the fuel spray which it discharges is directed obliquely into the combustion space 6 in the direction of a spherical impact head 10, which is the centrally situated part of an insertion pin 11 arranged offset in the combustion space 6 in a region facing away from the mouth of the conduit 7 (FIGS. 2-5) and, on its underside, has a cup-shaped recess 12, the plane d of which (as defined by the rim) is arranged obliquely by an angle β of about 25° towards the conduit 7 relative to a center plane f extending transversely to the center plane e of the insert 3. 
     The eccentric arrangement of the insertion pin 11 and of the conduit 7 gives rise, on the one hand, to a secondary inflow cross-section x and, on the other hand, to a main inflow cross-section y, with a cross-section ratio of between 0.55 and 0.8. The impact head 10 is provided on its cup-shaped underside with a bell mouth 10a, by which the inflowing air is additionally swirled. 
     Protruding into the combustion space 6 is a glow plug 13, the longitudinal axis of which lies in the plane g defined by the longitudinal axes a, b of insert 3 and conduit 7 (FIG. 2). The glow plug 13 is arranged on the side of combustion space 6, opposite the injection nozzle 4 and the conduit 7, to be precise in the upper half of the combustion space 6. The obliquely discharged fuel spray passes close by the glow pencil of the glow plug 13 and in part strikes that half of the upper side of the impact head 10 which is on the glow-plug side and in part strikes a niche 15 lying at the bottom of the combustion space 6. 
     FIG. 2 shows an illustrative embodiment in which the injection nozzle 4 and the glow plug 13 lie in the plane g extending through the longitudinal axes a, b of insert 3 and conduit 7 and in which the longitudinal axis h of the insertion pin 11 provided with the spherical impact head 10 lies at a right angle to this plane g. The longitudinal axis of the injection nozzle 4 can be rotated by a maximum of 50° in the clockwise direction or by a maximum of 20° in the anticlockwise direction about the longitudinal axis b of the insert 3. 
     FIG. 3 shows another illustrative embodiment in which the eccentrically situated conduit 7 is arranged in a position rotated by 50° in the clockwise direction relative to that in FIG. 2 about the longitudinal axis b of the insert 3, as in the position of the insertion pin 11. 
     FIG. 4 shows an illustrative embodiment which differs from the illustrative embodiment in accordance with FIG. 2 in that the injection nozzle 4 and the conduit 7 are both arranged in a position rotated by 50° in the clockwise direction about the longitudinal axis b of the insert 3, the longitudinal axis of the insertion pin 11 being situated in a position rotated by 110° in the anticlockwise direction from the plane g, about the longitudinal axis b of the insert 3. FIG. 5 shows an illustrative embodiment in which the injection nozzle 4 is arranged in a position rotated by 20° in the anticlockwise direction relative to that in accordance with FIG. 2, as is the insertion pin 11. 
     If required, the glow plug 13 can be arranged in a position rotated slightly in the clockwise or anticlockwise direction out of a basic position, about the longitudinal axis b of the insert 3. 
     Although the invention has been described and illustrated in detail, it is to be clearly understood that the same is by way of illustration and example, and is not to be taken by way of limitation. The spirit and scope of the present invention are to be limited only by the terms of the appended claims.