AT2332U1 - INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

In an externally ignited internal combustion engine with a centrally arranged ignition device (8) and a fuel introduction device (9) per cylinder (1), the surface (3) of the piston (2) has asymmetrical, arc-shaped first and second guide ribs (13, 14) that support the swirl movement of the cylinder charge ) each with concave inner (15, 16) and convex outer flow guide surfaces (17, 18), the inner flow guide surfaces (15, 16) being directed towards the ignition device (8) and with the initial regions (19, 20) of the guide ribs (13 , 14) have a greater distance from the ignition device (9) than its end regions (21, 22). The first and second guide ribs (13, 14) are spaced apart from one another, the second guide rib (14) being at least partially guided around the first guide rib (13), preferably around its end region (21). The two guide ribs (13, 14) form a channel-like curvature (23) in a region of the combustion chamber (6) opposite the fuel introduction device (9). This enables optimal atomization and ignition of the fuel.

Description

AT 002 332 Ul

The invention relates to an internal combustion engine with spark ignition and at least one reciprocating piston, with an ignition device arranged approximately in the region of the piston axis and at least one fuel introduction device per cylinder for direct fuel introduction to the piston axis, and with at least one inlet duct producing a swirl flow in the combustion chamber, wherein the surface of the piston has an asymmetrical, arc-shaped first guide rib which supports the swirl movement of the cylinder charge and has an inner and a convex outer flow guide surface, viewed in the direction of the piston axis, the inner flow guide surface of which is directed towards the ignition device and the starting area of which is a greater distance from the ignition device has as its end region.

Constantly increasing demands on fuel consumption and the reduction of exhaust emissions, especially of hydrocarbons, require the use of new technologies in the field of internal combustion engines. Due to the usual use of external mixture formation in gasoline engines, such as through the use of an intake manifold injection or a carburetor, part of the mixture drawn into the combustion chamber and cylinder flows into the exhaust tract of the internal combustion engine during the valve overlap phase when the exhaust and intake valves are open at the same time. A not inconsiderable part of the measurable unburned hydrocarbons in the exhaust tract also comes from mixture parts that are in annular gaps or areas near the wall during combustion, where no combustion takes place. In addition to these points, there is the necessary homogenization of the cylinder charge with an almost stoichiometric mixture ratio of fuel and air, which ensures safe and intermittent combustion. This requires control of the engine load with the help of a throttle device to limit the total amount of mixture sucked in (quantity control).

This throttling of the intake flow leads to a thermodynamic loss, which increases the fuel consumption of the internal combustion engine. The potential for reducing the consumption of the internal combustion engine by circumventing this throttling can be estimated at around 20%.

To prevent or reduce these disadvantages, attempts have long been made to operate spark-ignited internal combustion engines without throttling and to introduce the fuel only after the air intake has ended, as in the case of a self-igniting internal combustion engine, within the combustion chamber and cylinder or a directly connected mixing chamber.

There are basically three mixture formation systems: - High-pressure liquid injection 2 AT 002 332 Ul - Air-assisted fuel injection - Mixture injection.

A method is known from SAE 780699 in which the fuel is injected directly into the combustion chamber of the internal combustion engine by means of a high-pressure injection nozzle. The time required for the preparation of the mixture limits the minimum time interval between the injection point and the ignition point. A high pressure level is necessary for the injection process in order to obtain short injection times on the one hand and good atomization of the fuel on the other hand with a correspondingly small drop spectrum. The preparation and metering of the fuel takes place simultaneously. On the other hand, in order to obtain only a localized area with a combustible fuel-air mixture, it is necessary to introduce the fuel very late in the engine cycle (if necessary only during the compression shortly before the ignition), in order to allow the time for the mixture to spread and dilute limit the combustion chamber air. The demands for a sufficiently early injection for complete fuel vaporization and as late as possible injection to maintain the mixture stratification therefore conflict with one another. Development efforts must therefore focus on shortening the characteristic time for mixture preparation on the one hand and extending the characteristic time for maintaining the desired mixture stratification on the other.

The principle of an injection valve is known from SAE 940188, which achieves a conical injection jet with a high atomization quality of the fuel. The cone angle of the injection jet can be influenced by changing the fuel pressure and the combustion chamber back pressure. A characteristic property of such injection nozzles is the improvement of the atomization quality with increasing injection pressure. However, this desired dependency leads to likewise increasing speeds of the injection jet of up to 100 m / s and thus to a high impulse of the fuel spray entering the combustion chamber. In contrast, the air flow in the combustion chamber, even with strong inlet-generated swirl or tumble movement with a maximum of about 25-30 m / s, has only a significantly smaller pulse, which is why the injection jet in a first phase of entering the combustion chamber is only marginally influenced by the combustion chamber flow becomes.

Under these conditions, the task arises of generating a locally limited mixture cloud from the injection jet, transporting it from the mouth of the injection valve into the vicinity of the spark plug and further mixing the mixture within the cloud with combustion chamber air. The following points are essential:

The mixture cloud must remain clearly delimited, especially at low engine loads, and must be located in the center of the combustion chamber for thermodynamic reasons and to reduce the emissions of unburned hydrocarbons. 3 AT 002 332 Ul - The dilution of the blown-in mixture to a preferably stoichiometric air ratio must take place in the comparatively short period between the injection point and the ignition point. - At the spark plug there should be a low average flow velocity and at the same time a high level of turbulence in order to promote the ignition of the mixture cloud by the ignition spark.

When designing a suitable combustion process for a direct-injection gasoline engine, the available combustion chamber dimensions must also be taken into account in addition to the characteristics of the injection jet spread. Displacements of the single cylinder typical for car gasoline engines lead to bore diameters of approx. 65 to 100 mm, whereby the piston stroke is of the same order of magnitude.

If the injection valve is arranged in the cylinder head in a position inclined by a maximum of approximately 70 ° to the cylinder axis, in the case of late injection, the injection jet has a free propagation distance of max. 50 - 60 mm available before the injection jet hits the opposite combustion chamber wall (usually the piston surface). In view of the above-mentioned speeds of propagation of the injection jet, it must therefore be expected that at least some of the fuel spray will strike the piston surface. The design of the internal combustion chamber flow should therefore take this process of wall wetting into account.

The following effects can be used to form the mixture cloud and to prepare the fuel spray: - Redirecting the high impulse of the injection jet to the spark plug using the piston surface.

High injection pressure to improve atomization and thus to accelerate the direct evaporation of the fuel spray in front of the wall.

Generation of an increased level of turbulence in the area of the injection jet through the internal flow of the combustion chamber. - Acceleration of the wall film evaporation by generating a high flow velocity at the wetted area of the piston surface.

All measures that can be achieved by the internal combustion chamber flow require the generation of a high charge movement level during the intake process. These high flow velocities should be maintained for as long as possible during the intake and compression phase or even increased during the compression. This requirement can best be achieved by an inlet-generated swirl or tumble movement of the combustion chamber air. A swirl movement (rotation around the cylinder axis) represents the most stable flow structure in cylinders, which leads to the least dissipation of the kinetic energy during compression. By forming a compared to 4 AT 002 332 Ul

Cylinder diameter smaller piston bowl can achieve an increase in the rotational speed of the swirl vortex during compression due to the maintenance of the swirl.

On the one hand, an inlet-generated tumble vortex (rotation about an axis parallel to the crankshaft) shows an acceleration of the rotation by reducing the cross-sectional area during compression. On the other hand, the tumble vortex is more unstable compared to the swirl and tends to disintegrate into more complex secondary vertebrae. In the final phase of the compression, a strong decay of the tumble vortex into smaller stochastically distributed vertebrae can be observed with a sufficiently flat valve angle (a typical four-valve combustion chamber).

From AT 001 392 Ul an internal combustion engine with spark ignition and at least one reciprocating piston with a piston recess is known, which accelerates the inlet-generated swirl flow during the upward movement of the piston. The piston bowl is designed asymmetrically and has an inlet area with increasing trough depth, a central area with maximum trough depth and an outlet area with decreasing trough depth. A wedge-shaped constriction is provided on the side of a fuel introduction device between the outlet region and the inlet region. The shape of the piston recess means that, on the one hand, an impact of the fuel jets is deflected in the direction of the centrally located spark plug, and, on the other hand, the downward flow is deflected and accelerated by the piston recess shape during the compression, so that a flow directed towards the spark plug is included in the area where the fuel jets strike high speed is reached. However, the level of turbulence is not sufficient to ensure safe ignition of the fuel at any speed.

From JP 7-102976 A an internal combustion engine of the type mentioned at the beginning with a single arcuate guide rib is known, which directs the swirl flow into the area of the centrally arranged spark plug. The fuel is injected into a trough-shaped region of the piston end face delimited by the concave guide surfaces of the guide ribs through an injection nozzle arranged on the edge of the combustion chamber roof. Due to the lateral injection towards the cylinder axis, however, the fuel particles are thrown over the guide rib and deflected into an area delimited by a convex guide surface of the guide rib and the piston rim. The deflected power surge particles must first be guided through the swirl flow into the area of the spark plug again, a relatively long flow path extending over an angular range of more than 180 ° along the piston edge having to be covered. This means that the deflected fuel particles only arrive in the area of the spark plug at a relatively late point in time and are no longer available for the ignition of the mixture. This has a detrimental effect on hydrocarbon emissions and on fuel consumption.

The object of the present invention is to avoid these disadvantages and to improve the atomization and ignition of the fuel in an internal combustion engine of the type mentioned at the outset. 5 AT 002 332 Ul

According to the invention, this is achieved in that the surface of the piston has an asymmetrical, arc-shaped second guide rib which supports the swirl movement of the cylinder charge and has a concave inner and a convex outer flow guide surface, the inner flow guide surface of which is directed towards the ignition device, and the initial region of which is at a greater distance from the ignition device has as its end region that the first and second guide ribs are spaced apart and the second guide rib is at least partially guided around the first guide rib, preferably around its end region, and that the outer flow guide surface of the first guide rib and the inner flow guide surface of the second guide rib are at least in one form a channel-like constriction of the fuel introduction device with respect to the area opposite the piston axis. As a result, fuel particles deflected radially outward beyond the first guide rib are caught by the second guide rib in the region of the constriction. A part of the swirl flow is directed through the channel-like connection and pulls the stray fuel particles in the direction of the ignition device. Due to the accelerated swirl flow, which is led in particular through the second guide rib to the ignition device, the fuel particles reach the area of the ignition device after a very short time and can still contribute to the ignition of the fuel. Particularly good flow guidance in the ignition area is achieved if the curvature of at least one guide rib increases towards the end area. The end region of the first guide rib is preferably at a smaller distance from the ignition device than the end region of the second guide rib.

In order to accelerate the swirl flow for a rapid transport of the mixture into the ignition area, it can further be provided that the starting area of at least one guide rib, preferably the second guide rib, is arranged in the area of the piston rim.

In order to simultaneously obtain a high level of turbulence and flow for the mixture preparation and for the mixture transport in the ignition area, it is provided that at least in the end area of the first guide rib, its inner flow guide surface is directed towards the fuel introduction device. In this case, the surface of the piston advantageously lies partly on the side facing the crankshaft of a plane spanned by the piston edge.

The piston end face can have trough-like depressions, the trough bottom not having to be flat and also having a slight crowning in the direction of the ignition device.

In a preferred embodiment variant it is provided that the inner flow guide surface of at least one guide rib has an undercut of preferably 0 ° to 30 °, measured to a piston axis parallel. Heavy cuts are caught by the undercut and quickly evaporated by the high tangential speeds of the swirl flow. 6 AT 002 332 Ul

The guide ribs themselves can be kept extremely slim, for example the thickness s of the guide ribs is chosen such that: 0.05 * D < s < 0.13 * D, where D is the piston diameter. The low thickness of the guide ribs prevents excessive material accumulation in the combustion chamber area.

To maintain a high flow level in the combustion chamber, it is also advantageous if the minimum distance between the outer flow guide surface in the end region of the first guide rib and the inner flow guide surface of the second guide rib is between 0.05 * D and 0.25 * D, where D is the piston diameter is. The mixture preparation after the introduction of fuel is further favored if the distance between the outer flow guide surfaces of the first and second guide ribs - measured in an engine plane running through the piston axis transverse to the longitudinal axis of the fuel introduction device, in which the crankshaft axis is preferably - lies between 0.3 5 * D and 0.75 * D, where D is the piston diameter. In order to obtain an optimal flow return to the ignition area, it can further be provided that the distance b between the end area of the second guide rib and the piston axis is selected such that: 0.1 * D < b < 0.32 * D, where D is the piston diameter.

In order to achieve a good mixture preparation and a high acceleration of the swirl flow, it is furthermore advantageous if the initial region of the first guide rib is arranged in such a way that the following angular relationship applies: 170 ° < a, < 90 °, where a is the angle measured about the piston axis between a reference plane spanned by the piston axis and the mouth of the fuel delivery device on the one hand and the initial region of the first guide rib on the other hand, and the reference plane is preferably normal to the crankshaft axis. The end region of the first guide rib should lie in an angular range ct2 between -30 ° and -90 °, where a2 is the angle measured around the piston axis between the reference plane and the end region of the first guide rib.

Experiments have shown that a high tangential velocity of the swirl flow can be achieved if the initial region of the second guide rib is arranged in an angular range β, between 0 ° and 70 °, where β, the angle measured around the piston axis between the reference plane and the initial region of the second guide rib is. In order to quickly return the stray fuel particles to the ignition area, it is further provided that the end area of the second guide rib is arranged such that: -90 ° &lt; β2 <-160 °, where β2 is the angle measured around the piston axis between the reference plane and the end region of the second guide rib.

In particular in the case of design variants with a plurality of inlet valves, it has proven to be advantageous for the acceleration of the swirl flow if the initial region of the first guide rib is arranged under an inlet valve. The end region of the second guide rib can be arranged under an intake valve both in engines with one and with a plurality of intake valves. 7 AT 002 332 Ul

The height of the guide ribs is advantageously adapted to the shape of the combustion chamber cover surface, it being preferably provided that the guide ribs in the top dead center of the piston movement come close to and essentially parallel to the remaining roof-shaped combustion chamber cover surface, preferably between 1 and 5 mm this run. It is entirely sufficient if the maximum height h ^ of the guide ribs is chosen such that: 0.07 * D &lt; h ^ c 0.25 * D, where D is the piston diameter. An excessive increase in the piston can be avoided.

The invention is explained in more detail with reference to the figures.

1 shows the internal combustion engine according to the invention in a longitudinal section through the piston along the line II in FIG. 2, FIG. 2 shows a top view of the partially cut piston according to the line II-II in FIG. 1, FIG. 3 shows a longitudinal section through the piston according to the line III-III in Fig. 2, Fig. 4 shows an embodiment of the piston according to the invention in longitudinal section analogous to Fig. 3, Fig. 5 shows an embodiment of the invention for internal combustion engines with three valves per cylinder, Fig. 6 shows an embodiment of the Invention for internal combustion engines with two valves per cylinder.

Parts with the same function are provided with the same reference symbols in the design variants.

A reciprocating piston 2 is arranged in a cylinder 1. The surface 3 of the piston 2, together with the combustion chamber cover surface 5, which is roof-shaped by the cylinder head 4, forms a combustion chamber 6, in which an ignition device 8 and a fuel introduction device 9, whose mouth 10 is located at the edge of the combustion chamber 6, open in the region of the piston axis 7. The longitudinal axis of the fuel introduction device is designated by 11. The fuel introduction device 9 is arranged such that an injected fuel jet 12 is directed toward the piston axis 7 and the fuel jet 12 strikes the surface 3 of the piston 2 approximately in the area of the center of the combustion chamber at the top dead center of the piston 2.

The surface of the piston 2 has a first guide rib 13 and a second guide rib 14, both guide ribs 13, 14 being designed asymmetrically and in an arc shape. The concave, inner flow guide surfaces 15 and 16 of the first guide rib 13 and the second guide rib 14 are - viewed in the direction of the piston axis 7 - directed towards the ignition device 8. The outer flow guide surfaces of the first guide rib 13 and the second guide rib 14 are denoted by 17 and 18, respectively. The initial area 19 or 20 of the first guide rib 13 or the second guide rib 14 lies in the area of the piston rim 2a. The first guide rib 13 and the second guide rib 14 approach the ignition device 8 in continuously increasing, curved arches away from the starting area 19, 20, the end area 21 of the first guide rib 13 being at a smaller distance from the ignition device 8 than the end area 22 of the second guide rib 14 On the piston side opposite the mouth 10 of the fuel delivery device 9, the outer flow guide surface 17 of the first guide rib 8 AT 002 332 Ul 13 forms a channel-shaped constriction 23 with the inner flow guide surface 18 of the second guide rib 14, as can be seen in FIGS .

The initial region 19 is at an angle a, between 90 ° and 170 °, the angle a being measured away from a reference plane 24 spanning the piston axis 7 and the mouth 10. The reference plane 24 can coincide with the engine transverse plane 25 or be inclined to it (FIG. 6).

The end region 21 of the first guide rib 13 is arranged such that: -30 ° &lt; a2 &lt; -90 °, based on the reference plane 24. The initial region 20 of the second guide rib 14 is in an angular range β, between 0 and 70 ° from the reference plane 24. The end region 22 of the second guide rib 14 is located on the side of the fuel delivery device 9, the condition: -90 ° &lt; β2 <-160 ° is satisfied. The angle β2 is measured from the reference plane 24 to the end region 22 of the second guide rib 14.

The end region 22 of the second guide rib 14 is at a distance b from the ignition device 8 between 0.1 times the piston diameter D and 0.32 times the piston diameter D. The first guide rib 13 and second guide rib 14 are - measured in a motor plane 26 extending through the piston axis 7 transverse to the longitudinal axis 11 of the fuel introduction device 9 - spaced apart from one another by a value a between 0.35 times the piston diameter D and 0.75 times the piston diameter D. . The minimum distance c between the outer flow guide surface 17 in the end region 21 of the first guide rib 13 and the inner guide surface 16 of the second guide rib 14 is between 0.05 times the piston diameter D and 0.25 times the piston diameter D.

The first and second guide ribs 13, 14 can be made very narrow, the thickness s of the guide ribs being between 0.05 and 0.12 times the piston diameter D. This avoids excessive material accumulation in the combustion chamber area. The height of the first and second guide ribs 13, 14 is selected so that the guide ribs 13, 14 approach the roof-shaped combustion chamber top surface 5 and are essentially parallel to one another at the top dead center of the piston movement, except for a remaining distance which can be between 1 and 5 mm this run. The maximum height h ^ is between 0.07 and 0.25 times the piston diameter D.

The piston design according to the invention is not limited to a specific number of valves. It is suitable both for internal combustion engines with two intake valves 27 and two exhaust valves 28, as shown in FIG. 2, but also for internal combustion engines with two intake valves 27 and a single exhaust valve 28 (FIG. 5), and also for internal combustion engines with one intake valve 27 and an exhaust valve 28 as shown in FIG. 6.

The surface 3 of the piston 2 can partially lie on the side of the plane 29 spanned by the piston edge 2a facing the crankshaft axis. It is possible, 9 AT 002 332 Ul, that the area of the surface 3 lying between the inner flow guide surfaces 15 and 16 of the first guide rib 13 and the second guide rib 14 is designed as a piston recess.

A fuel jet 12 injected by the fuel introduction device 9 strikes the surface 3 of the piston 2 approximately in the region of the piston axis 7. Due to the lateral injection, fuel particles may bounce back from the surface and be thrown over the first guide rib 13. They get into the constriction 23 behind the first guide rib 13, which is delimited by the second guide rib 14 and are entrained by the swirl flow accelerated in this area and are returned between the two guide ribs 13, 14 into the area of the ignition device 8. Due to the special design of the first and second guide ribs 13, 14, the fuel particles have to cover only a very short flow path, which is why they arrive at the ignition device 8 after a short delay and can participate in the ignition of the fuel.

As indicated by flow arrows 30 and 31 in FIGS. 2, 5 and 6, the inlet-generated swirl flow is supported by the guide ribs 13, 14. In this case, both the flow 30 guided between the outer flow guide surface 17 of the first guide rib 13 and the inner flow guide surface 16 of the second guide rib 14 and the flow 31 guided outside the outer flow guide surface 18 of the second guide rib 14 are guided into the area of the ignition device 8 near the piston axis 7 .

As indicated in FIG. 4, the inner flow guide surfaces 15 and 16 of the first guide rib 13 and the second guide rib 14 can be undercut by an angle δ which, based on a piston axis parallel 7a, can be between 0 ° and 30 °. This has the advantage that heavier mixture parts are trapped and are rapidly evaporated there by the high tangential speeds of the currents 30 and 31.

The best results are achieved with a roof-shaped combustion chamber top surface 5, the valve angle γ spanned by the inlet valve axis 27a and the outlet valve axis 28a being approximately 10 to 60 °. 10th

Claims (19)

AT 002 332 Ul PROTECTION CLAIMS 1. Internal combustion engine with spark ignition and at least one reciprocating piston (2), with an ignition device (8) arranged approximately in the area of the piston axis (7) and at least one fuel introduction device (9) per cylinder (1) direct fuel introduction to the piston axis (7), and with at least one inlet duct producing a swirl flow in the combustion chamber (6), the surface (3) of the piston (2) also having an asymmetrical, arc-shaped first guide rib (13) that supports the swirl movement of the cylinder charge one - viewed in the direction of the piston axis (7) - has a concave inner (15) and a convex outer flow guide surface (17), the inner flow guide surface (15) of which is directed towards the ignition device (8), and whose initial region (19) is at a greater distance from Ignition device (8) has as its end region (21), characterized in that the surface (3) of the piston (2) has a dra Asymmetrical, arc-shaped second guide rib (14) supporting the cylinder charge with a concave inner (16) and a convex outer flow guide surface (18), the inner flow guide surface (16) of which is directed towards the ignition device (8), and the initial region (20) is at a greater distance from the ignition device (8) than its end region (22), that the first and second guide ribs (13, 14) are spaced apart and the second guide rib (14) is at least partially around the first guide rib (13), preferably around its end region (21), and that the outer flow guide surface (17) of the first guide rib (13) and the inner flow guide surface (16) of the second guide rib (14) at least in one of the fuel introduction device (9) with respect to the piston axis (7) opposite Area form a trough-like narrowing (23). 2. Internal combustion engine according to claim 1, characterized in that the curvature of at least one guide rib (13, 14) increases towards the end region (21, 22). 3. Internal combustion engine according to claim 1 or 2, characterized in that the end region (21) of the first guide rib (13) is at a smaller distance from the ignition device (8) than the end region (22) of the second guide rib (14). 4. Internal combustion engine according to one of claims 1 to 3, characterized in that the initial region (19, 20) of at least one guide rib (13, 14), preferably the second guide rib (14), is arranged in the region of the piston rim. 5. Internal combustion engine according to one of claims 1 to 4, characterized in that at least in the end region (21) of the first guide rib (13) whose inner flow guide surface (15) is directed towards the fuel introduction device (9). 11 AT 002 332 Ul 6. Internal combustion engine according to one of claims 1 to 5, characterized in that the surface (3) of the piston (2) is partly on the side facing the crankshaft of a plane (29) spanned by the piston edge (2a). 7. Internal combustion engine according to one of claims 1 to 6, characterized in that the inner flow guide surface (15, 16) at least one guide rib (13, 14) an undercut (δ) of preferably 0 ° to 30 °, measured to a piston axis parallel (7a ), having. 8. Internal combustion engine according to one of claims 1 to 7, characterized in that the maximum height 1ι "of the guide ribs (13, 14) is selected so that applies: 0.07 * D ch ^ 0.25 * D, where D is the Piston diameter is. 9. Internal combustion engine according to one of claims 1 to 8, characterized in that the thickness s of the guide ribs (13, 14) is selected such that the following applies: 0.05 * D &lt; s &lt; 0.13 * D, where D is the piston diameter. 10. Internal combustion engine according to one of claims 1 to 9, characterized in that the minimum distance (c) between the outer flow guide surface (17) in the end region (21) of the first guide rib (13) and the inner flow guide surface (16) of the second guide rib ( 14) is between 0.05 * D and 0.25 * D, where D is the piston diameter. 11. Internal combustion engine according to one of claims 1 to 10, characterized in that the distance (a) between the outer flow guide surfaces (17, 18) of the first and second guide rib (13, 14) - measured in a through the piston axis (7) Engine plane (26) transverse to the longitudinal axis (11) of the fuel introduction device (9), in which the crankshaft axis is preferably - is between 0.35 * D and 0.75 * D, where D is the piston diameter. 12. Internal combustion engine according to one of claims 1 to 11, characterized in that the distance b between the end region (22) of the second guide rib (14) and the piston axis (7) is chosen such that: 0.1 * D &lt; b &lt; 0.32 * D, where D is the piston diameter. 13. Internal combustion engine according to one of claims 1 to 12, characterized in that the initial region (19) of the first guide rib (13) is arranged such that the following angular relationship applies: 170 ° &lt; a, &lt; 90 °, where a is the angle measured around the piston axis (7) between a reference plane (24) spanned by the piston axis (7) and the mouth (10) of the fuel introduction device (9) on the one hand and the initial region (19) of the first guide rib ( 13) on the other hand, and wherein the reference plane (24) is preferably normal to the crankshaft axis. 14. Internal combustion engine according to one of claims 1 to 13, characterized in that the end region (21) of the first guide rib (13) is arranged such that the following applies: -30 ° &lt; a2 &lt; -90 °, 12 AT 002 332 Ul where a2 is the angle measured around the piston axis (7) between the reference plane (24) and the end region (21) of the first guide rib (13). 15. Internal combustion engine according to one of claims 1 to 14, characterized in that the initial region (20) of the second guide rib (14) is arranged such that: 0 ° &lt; ß, &lt; 70 °, where β is the angle, measured around the piston axis (7), between the reference plane (24) and the initial region (20) of the second guide rib (14). 16. Internal combustion engine according to one of claims 1 to 15, characterized in that the end region (22) of the second guide rib (14) is arranged such that: -90 ° &lt; ß2 &lt; -160 °, where β2 is the angle measured around the piston axis (7) between the reference plane (24) and the end region (22) of the second guide rib (14). 17. Internal combustion engine according to one of claims 1 to 16, characterized in that the initial region (19) of the first guide rib (13) is arranged under an inlet valve (27). 18. Internal combustion engine according to one of claims 1 to 17, characterized in that the end region (22) of the second guide rib (14) is arranged under an inlet valve (27). 19. Internal combustion engine according to one of claims 1 to 18, characterized in that the guide ribs (13, 14) in the top dead center of the piston movement up to a remaining distance, preferably between 1 and 5 mm, the preferably roof-shaped combustion chamber cover surface (5) approximate and run essentially parallel to this. 13