DE102004032818A1 - Injector for injecting fuel into a combustion chamber of a diesel engine - Google Patents

Abstract

An injection nozzle (42) for injecting fuel into a combustion space (14) of a diesel engine via at least one first partial jet (44) and at least one second partial jet (46) which is emitted simultaneously with the first partial jet (44) is presented Direction (46) of a first partial beam (44) on a first cone sheath with a first opening angle (28). The injection nozzle (42) is characterized in that one direction (52, 54) of at least one second partial jet (48, 50) lies on a second cone shell with a second opening angle (56) which is smaller than the first opening angle (28) ,

Description

The The invention relates to an injection nozzle for the injection of fuel in a combustion chamber of a diesel engine via at least a first Partial beam and at least a second partial beam, the same time is output with the first partial beam, wherein a direction of a first partial beam on a first cone sheath with a first opening angle.

A such injector is, for example, from the Automotive Handbook, 23rd Edition, Page 556 known. The injectors shown there are for an inclined installation provided in a cylinder head of an internal combustion engine and give through several injection holes Partial rays whose directions lie on a cone. The axis of the Kegels goes through the piston, which moves the combustion chamber seals. The opening angle of the cone of these known injection nozzles is in the range of 140 up to 160 degrees. This geometry results in an injection in a comparatively flat volume. Fits to the done Injection relatively late near top dead center of compression of the upwardly moving piston.

Because of the late Injection into a highly compressed air filling represents a mixture preparation in the combustion chamber only a very short period of time until the onset of Combustion available. Of the injected fuel is therefore not distributed homogeneously throughout Combustion chamber. Instead, charge clouds are formed in the combustion chamber the or the injection jets in which the fuel concentration from the inside to the outside decreases. This type of charge distribution is also referred to as stratified combustion chamber filling.

When Side effect occurs at this comparatively wide opening angle a good cold start ability on. The good cold start ability results from the fact that because of the wide opening angle fuel in the roundabouts a arranged in the cylinder head glow plug is injected. The glow plug is heated electrically in the cold start case and makes it easier to ignite the filling of the combustion chamber.

To diesel engines will also be able to respond to newer development trends in the future with homogeneous combustion chamber fillings work. A homogeneous distribution of the fuel in the combustion chamber gets through a comparatively early and deep into the combustion chamber reaching, far before the top dead center of compression takes place Injection achieved, allowing for a homogeneous distribution of the fuel in the combustion chamber more time to disposal stands. The homogeneous distribution is also supported by the fact that the up running piston during further compression of the combustion chamber filling Air and fuel swirled.

The size Penetration depth in this process results from the fact that the fuel in a much sharper opening angle towards the upwards current, but still comparatively far away piston injected becomes.

at Trying with such new combustion has become essential worse cold start capability as with usual Diesel engines with direct injection shown.

In front In this background, the object of the invention in the specification of measures, the one for one Improvement of cold start ability for diesel engines with homogeneous combustion processes.

These Task is with an injection nozzle of the type mentioned solved by a direction of at least a second partial beam on a second cone sheath with a second opening angle is smaller as the first opening angle is.

Advantages of invention

By This measure the task is completely solved. The invention is based on the finding that the undesirable effect the deterioration of cold start capability is less a direct one The result of homogeneous combustion is, but rather a direct Result of the much smaller opening angle of a cone of injection directions at a homogeneous combustion process is.

According to the invention two opening angles used, so that a distribution of the injection quantity in at least an ignition jet and gives further rays, which for a homogeneous mixture distribution in the combustion chamber. It is preferable that the second opening angle between 30 and 130 degrees.

It has shown that with this opening angle a very good homogeneity the fuel distribution can be achieved.

Prefers is also that the first opening angle between 130 and 160 degrees.

This Angular interval is approximately the usual for one layered charge used angular interval at which a good cold start capability showed.

Thereby, that in the injector according to the invention at least a partial beam in one for one layered charge usual Angle direction, a can be mounted as usual in the cylinder head Heating device, such as a glow plug, much more Heat in inject the injected fuel, which helps to ignite low combustion chamber temperatures and thus the cold start capability in a homogeneous combustion diesel engine significantly improved.

It is preferred that the injection nozzle at the same time exactly one first partial beam and a plurality of second partial beams outputs.

By This embodiment is achieved that a majority of the injected Fuel for a homogeneous distribution is available and only a minor one Amount for an improvement in cold start capability is branched off. This will sacrifice the benefits that through a largely homogeneous distribution of the fuel in the combustion chamber, only slightly reduced.

Further is preferred that in each case a partial beam by an associated Injection hole issued at a combustion chamber end of the injection nozzle becomes.

The Output of fuel over several Injection holes allows a reproducible distribution of the amount of fuel to be injected on several partial beams, what for An optimization of a subsequent combustion is essential.

Prefers is also that the two cone coats have the same cone axis and that n injection jets on the two cone coats are distributed so that when projecting the n directions the injection jets on a plane perpendicular to the cone axis a n-fold Symmetry results. An arrangement has an n-fold symmetry, when they are self-imaging when rotated 360 ° / n becomes.

With This feature is as far as possible Achieved rotational symmetry of the arrangement of the injection jets. Thus, the arrangement of the injection jets as much as possible the symmetry adapted to the volume of air injected into. Because the injection takes place relatively early in a homogeneous combustion process, this air volume is essentially due to the cylinder shape over the up defined current piston.

A Another preferred embodiment is characterized in that a partial beam whose direction lies on the first cone sheath, has a smaller penetration depth into a combustion chamber than a partial jet, whose direction lies on the second cone sheath.

These Design considered, that the partial beam on the first cone sheath substantially transversely is radiated to the cylinder axis and that a central in the direction the cylinder axis arranged injector only by a comparatively small distance from a lateral cylinder wall is separated. At a quadratic ratio from cylinder bore diameter to piston stroke is the distance a piston at bottom dead center to the injection nozzle about twice as large as the Removal of injector from the cylinder jacket. At an early, with the aim of a homogeneous mixture distribution injection is therefore a comparatively large one Seek penetration depth in the cylinder. Would the subtray be in a flatter angle is output, with a comparable Penetration depth would be spent he hit the cylinder wall or combustion chamber wall, which is not desirable. An impact on the cylinder wall could, for example, the lubricating film affect and an impact liquid Fuel on a hot glow plug would be too locally high temperature fluctuations and thus to mechanical loads the glow plug to lead.

Further it is preferred that the injection holes are dimensioned that over a second partial beam at an injection a larger mass of fuel is injected as over a first partial beam.

These On the one hand, the design effects the lower penetration depth of the ignition spray and do about it in addition, that the larger amount of fuel for the desirable homogeneous distribution in the cylinder is available and only possible little fuel for an ignition jet must be diverted. This will result in losses resulting from the break the symmetry of the injection jet arrangement with a warm combustion engine can result, kept small.

Prefers is also that the injection holes so are dimensioned that over two second partial beams at an injection equal amounts of fuel be measured.

This Feature carries to the widest possible extent Maintaining symmetry of fuel distribution in the cylinder and thus positively influences combustion.

A further preferred embodiment is characterized in that the injection nozzle has markings for determining a built-in rotational angle position. It is further preferred that the Markers define a built-in rotation angle position in which a first partial beam has a predetermined orientation to a heater or igniter in the combustion chamber.

By these embodiments, it is possible to injection installed in a cylinder head so that the first partial jet, so the ignition, in a predetermined direction in the combustion chamber, in which a possible slight ignition is to be expected. This can be for example the Direction in which a glow plug is arranged as a cold start aid.

Prefers is also that the first partial beam directed to a heater is.

These Arrangement ensures that the cold start improvement potential the injection jet arrangement according to the invention also comes into play, if one arranged at a certain angle Heating device is used. For annular or other, over the Scope of the cylinder distributed heaters would be this Characteristic dispensable.

Further It is preferred that the markings form a positive rotation exhibit.

A Another preferred embodiment is characterized by a fastening means for axially fixing the injection nozzle in a cylinder head of a Internal combustion engine off.

at Such a configuration is particularly preferred that the fastening means a threaded sleeve or a union nut exhibit.

By these embodiments is at the same time an angular orientation a longitudinal axis the injector and a high-strength mounting of the injection nozzle through in the direction of the longitudinal axis acting clamping forces possible.

Further Advantages will be apparent from the description and the attached figures.

It it is understood that the above and the following yet to be explained features not only in the specified combination, but also in other combinations or alone, without to leave the scope of the present invention.

drawings

embodiments The invention are illustrated in the drawings and in the following description explained. Show it:

1 schematically a combustion chamber with a known, centrally arranged injector for a stratified diesel combustion process;

2 schematically a combustion chamber with an injection nozzle according to the invention for a homogeneous diesel combustion process; and

3 a viewed from the direction of a piston injection nozzle as an embodiment of an injection nozzle according to the invention.

description the embodiments

In the 1 is an injector 10 shown, the combustion chamber side end 12 in a combustion chamber 14 protrudes. The injector 10 indicates at its combustion chamber end 12 Holes or openings 16 . 18 . 20 on, over the injection jets 22 in an air filling of the combustion chamber 14 be issued. In this case, the output of the injection jets takes place 22 in different directions 24 . 26 that define a first opening angle of a first cone shroud.

The combustion chamber 14 gets up through a cylinder head 30 and to the sides by a cylinder jacket 32 limited and by a piston 34 movably sealed. The numeral 36 in the 1 marks the position of a top dead center of movement of the piston 34 in the cylinder jacket 32 , The presentation of the 1 represents a known combustion chamber and injection jet geometry as used in conjunction with a late fuel injection for the formation of a stratified combustion chamber charge. The injection takes place relatively late, so only shortly before the piston 34 its top dead center 36 reached. Accordingly, the remaining volume of the combustion chamber 14 at this time comparatively flat and wide. This geometry of the combustion chamber 14 At the time of injection is taken into account by a geometry of the injection jet angle, which is characterized by a comparatively wide first opening angle 28 distinguished. The first opening angle 28 lies in the in the 1 illustrated boundary conditions typically between 130 and 160 °.

To improve the cold start properties is usually in the cylinder head 30 a glow plug 38 arranged, the combustion chamber side end 40 is electrically heated. The very wide first opening angle, which is an interval between 130 ° and 160 °, as used in the prior art, has shown good cold start properties.

2 schematically shows a combustion chamber 14 with an injection nozzle according to the invention 42 for a homogeneous diesel combustion process. The injector 42 gives a first partial beam 44 in a direction 46 made on a first cone sheath with a first opening angle 28 lies. In addition, there is the injector 42 at least a second partial beam 48 and or 50 in a second direction 52 and or 54 out, each on a second cone sheath with a second opening angle 56 lie, which is smaller than the first opening angle 28 is. The second opening angle 56 is preferably in an interval between 30 ° and 130 °, during the first opening angle 28 the known from the prior art forth usual opening angle from the interval between 130 and 160 ° corresponds.

The second partial beams 48 and 50 be with the comparatively small opening angle 56 injected to achieve a large penetration depth with a comparatively early injection. The piston 34 is still relatively far from its top dead center in this case 36 removed, leaving the known injection geometry, as in the 1 is pictured, would capture only a portion of the combustion chamber volume. The piston continues to rise during and after an injection 34 swirls the injected fuel with the air filling of the combustion chamber 14 , so that as a result, a largely homogeneous fuel-air mixture distribution in the combustion chamber 14 results.

To ensure reliable ignition of the combustion chamber filling even at low temperatures of the combustion chamber 14 and the cylinder jacket 32 , the cylinder head 30 and the piston 34 to ensure the first partial beam 44 preferably with the flatter, or wider, first opening angle 28 discontinued. This is done with the aim of local fuel enrichment at the combustion chamber end 40 the glow plug 38 to achieve. With a suitable orientation of the injection nozzle 42 Sufficient to a single first partial beam 44 out, the one in comparison to the second partial beams 48 and 50 has less penetration and also transported less fuel.

By injecting a comparatively small amount of fuel in the vicinity of the combustion chamber end 40 the glow plug 38 and by dosing the majority of the injected fuel by second partial beams 48 at an acute angle into the depth of the combustion chamber 14 Both a homogeneous diesel combustion process can be realized as well as a reliable ignition of the combustion chamber fillings at low temperatures can be achieved. The first partial beam 44 thus serves as a kind of ignition. He is, for example, by a smaller injection hole 16 , designed for a lower injection quantity than the other partial beams 48 . 50, to influence the pollutant emissions with warm combustion engine as little as possible.

By reducing the first partial beam 44 Transporting fuel quantity will also increase the penetration depth of the first sub-jet 44 in the combustion chamber 14 reduced. The injector 42 is preferred in the cylinder head 30 used that the first sub-beam 44 in the direction of the glow plug 38 is discontinued. For this purpose, the injector 42 at its periphery a firm mark 58 have, the form-fitting manner in a correspondingly formed counterpart of the cylinder head 30 fits and the injector 42 in the desired angular position. fixed. In the axial direction, the injector 42 preferably by means of threaded sleeves, banjo bolts, union nuts or claws with the cylinder head 30 braced.

3 shows a from the direction of the piston 34 considered injection pattern of an embodiment of an injection nozzle 42 , The injector after the 3 has a first injection port 16 and seven second injection ports 18 on. The total of eight injection ports 16 . 18 are arranged so that the directions of the output partial beams have an eightfold symmetry. It is preferred that via the second injection openings 18 each with the same injection quantities are output, so that via the injection openings 18 output partial beams 48 have the same penetration depth. In contrast, the first partial beam 44 have a lower penetration depth and transport a lower fuel mass. This is in the 3 by one compared to the second sub-beams 48 shortened partial beam 44 shown.

Claims (15)

Injector ( 42 ) for injecting fuel into a combustion chamber ( 14 ) of a diesel engine via at least a first partial beam ( 44 ) and at least a second sub-beam ( 46 ), which coincides with the first sub-beam ( 44 ) is output, with one direction ( 46 ) of a first sub-beam ( 44 ) on a first cone shell with a first opening angle ( 28 ), characterized in that one direction ( 52 . 54 ) at least one second sub-beam ( 48 . 50 ) on a second cone shell with a second opening angle ( 56 ), which is smaller than the first opening angle ( 28 ). Injector ( 42 ) according to claim 1, characterized in that the second opening angle ( 56 ) is between 30 and 130 degrees. Injector ( 42 ) according to claim 1 or 2, characterized in that the first opening angle ( 28 ) is between 130 and 160 degrees. Injector ( 42 ) according to at least one of claims 1 to 3, characterized in that the Injector ( 42 ) at the same time exactly a first partial beam ( 44 ) and a plurality of second partial beams ( 48 . 50 ). Injector ( 42 ) according to at least one of the preceding claims, characterized in that in each case a partial beam ( 44 . 48 . 50 ) through an associated injection hole ( 16 . 18 . 20 ) at a combustion chamber end of the injection nozzle ( 42 ) is output. Injector ( 42 ) according to at least one of the preceding claims, characterized in that the two cone shells have the same cone axis and that n injection jets ( 44 . 48 . 50 ) are distributed on the two cone shells in such a way that when the directions ( 46 . 52 . 54 ) of the injection jets ( 44 . 48 . 50 ) gives an n-fold symmetry on a plane perpendicular to the cone axis. Injector ( 42 ) according to one of the preceding claims, characterized in that a partial beam ( 44 ), whose direction lies on the first cone sheath, a smaller penetration depth into a combustion chamber ( 14 ) has as a partial beam ( 48 . 50 ), whose direction ( 52 . 54 ) lies on the second cone coat. Injector ( 42 ) according to at least one of claims 5 to 7, characterized in that the injection holes ( 16 . 18 . 20 ) are dimensioned so that over a second partial beam ( 48 . 50 ) is injected with an injection of a larger mass of fuel than via a first partial beam ( 44 ). Injector ( 42 ) according to claim 5, characterized in that the injection holes ( 16 . 18 . 20 ) are dimensioned so that over two second partial beams ( 48 . 50 ) are metered at an injection equal amounts of fuel. Injector ( 42 ) according to at least one of the preceding claims, characterized in that the injection nozzle ( 42 ) Markings ( 58 ) for fixing a built-in rotation angle position. Injector ( 42 ) according to claim 10, characterized in that the markings ( 58 ) define a built-in rotation angle position in which a first partial beam ( 44 ) a predetermined orientation to a heating device ( 38 ) or ignition device in the combustion chamber. Injector ( 42 ) according to claim 11, characterized in that the first partial beam ( 44 ) to a heating device ( 38 ). Injector ( 42 ) according to at least one of claims 10 to 12, characterized in that the markings ( 58 ) form a positive rotation. Injector ( 42 ) according to at least one of the preceding claims, characterized by a fastening means for axially fixing the injection nozzle ( 42 ) in a cylinder head ( 30 ) of an internal combustion engine. injection according to claim 14, characterized in that the fastening means a threaded sleeve or a union nut exhibit.