阅读说明：本技术 内燃机 (Internal combustion engine ) 是由 W·布拉克 F·施瓦茨米勒 D·萨卡特 A·希雷特 T·克莱斯 L·谢弗 于 2018-08-08 设计创作，主要内容包括：本发明涉及一种用于机动车的内燃机(10),所述内燃机具有至少一个气缸(12)、缸盖(14)和在气缸(12)中可运动地支承的活塞(16),所述活塞具有燃烧室侧面(18),所述燃烧室侧面与缸盖(14)和气缸(12)一起限定燃烧室(20),所述缸盖(14)具有燃烧室顶(21),在燃烧室顶中设置至少两个阀座(22、24),所述至少两个阀座用于至少一个进气阀(26)和至少一个排气阀(28),并且所述燃烧室顶(21)具有至少一个设置在所述至少两个阀座(22、24)之间的、背离燃烧室(20)地定向的、拱曲的缸盖区段(46、47)。(The invention relates to an internal combustion engine (10) for a motor vehicle, comprising at least one cylinder (12), a cylinder head (14) and a piston (16) which is mounted so as to be movable in the cylinder (12) and which has a combustion chamber side (18) which, together with the cylinder head (14) and the cylinder (12), delimits a combustion chamber (20), wherein the cylinder head (14) has a combustion chamber ceiling (21) in which at least two valve seats (22, 24) are provided for at least one intake valve (26) and at least one exhaust valve (28), and wherein the combustion chamber ceiling (21) has at least one curved cylinder head section (46, 47) which is arranged between the at least two valve seats (22, 24) and is oriented away from the combustion chamber (20).)

1. An internal combustion engine (10) for a motor vehicle, having at least one cylinder (12), a cylinder head (14) and a piston (16) movably mounted in the cylinder (12), which has a combustion chamber side (18) that, together with the cylinder head (14) and the cylinder (12), delimits a combustion chamber (20), the cylinder head (14) having a combustion chamber ceiling (21), in which at least two valve seats (22, 24) are provided for at least one intake valve (26) and at least one exhaust valve (28), and the combustion chamber ceiling (21) having at least one curved cylinder head section (46, 47) which is arranged between the at least two valve seats (22, 24) and is oriented away from the combustion chamber (20).

2. Internal combustion engine (10) according to claim 1, characterized in that the effective area (41) of the combustion dome (21) is formed essentially without edges.

3. Internal combustion engine (10) according to one of the preceding claims, characterized in that the combustion dome (21) is made completely cut.

4. Internal combustion engine (10) according to one of the preceding claims, characterized in that the piston (16) has a rotationally symmetrical, in particular lens-shaped, recess (50) with respect to a piston axis (54), the diameter (D) of the recess (50) being smaller than the overall diameter (D) of the piston (16).

5. Internal combustion engine (10) according to claim 4, characterized in that the recess (50) has a depth between 0.2mm and 10mm, in particular between 0.5mm and 8mm, at its centre point.

6. Internal combustion engine (10) according to one of claims 4 and 5, characterized in that the recess (50) encloses an approximately spherical space together with the combustion dome (21), in particular together with the active area (41) of the combustion dome (21).

7. Internal combustion engine (10) according to one of the preceding claims, characterized in that the cylinder head (14) has pressing surfaces (32, 34) in the form of circular surface sections only on two edge sections lying opposite one another, which are each delimited by one of two transitions (42, 44) in the cylinder head (14) running parallel to one another, the two pressing surfaces (32, 34) having different surface sizes.

8. Internal combustion engine (10) according to claim 7, characterized in that the pressing surfaces (32, 34) are associated with an inlet side and an outlet side of the cylinder head (14), in particular the pressing surface (32) associated with the inlet side has a larger area than the pressing surface (34) associated with the outlet side.

9. Internal combustion engine (10) according to one of the preceding claims, characterized in that a screen (48) is provided in the combustion dome (21) beside the valve seat (22) parallel to the valve axis of the intake valve (26), said screen having a height of between 2mm and 3.5 mm.

10. Internal combustion engine (10) according to one of the preceding claims, characterized in that two curved head sections (46, 47) are provided, which are each arranged between two valve seats (22, 24) which are assigned to one inlet valve (26) and one outlet valve (28).

Technical Field

The invention relates to an internal combustion engine for a motor vehicle.

Background

Internal combustion engines usually have at least one cylinder, a cylinder head and a piston movably mounted in the cylinder. These elements collectively define a combustion chamber of the internal combustion engine in which a mixture comprising at least air and fuel is combusted.

During the combustion process, the piston moves up and down between top dead center and bottom dead center, which are also referred to as top dead center and bottom dead center. The mixture in the combustion chamber may be compressed when the piston moves upward, particularly when the piston moves toward the cylinder head. If the piston reaches top dead center, a spark plug disposed in the cylinder head ignites the mixture by generating an initial flame.

In order to achieve as rapid and efficient a combustion of the mixture as possible, it is advantageous if the mixture has as high a Turbulent Kinetic Energy (TKE) as possible. The turbulent kinetic energy is derived from the flow properties of the mixture and is decisively influenced by the geometry of the combustion chamber.

Disclosure of Invention

The object of the present invention is therefore to provide an internal combustion engine for a motor vehicle with an optimized combustion chamber.

The object is solved according to the invention by an internal combustion engine for a motor vehicle having at least one cylinder, a cylinder head and a piston movably mounted in the cylinder, the piston having a combustion chamber side which, together with the cylinder head and the cylinder, delimits a combustion chamber, the cylinder head having a combustion chamber ceiling in which at least two valve seats are arranged for at least one intake valve and at least one exhaust valve, and the combustion chamber ceiling having a curved cylinder head section arranged between the at least two valve seats and oriented away from the combustion chamber.

By means of the curved cylinder head section, which is oriented away from the combustion chamber, the combustion chamber dome can have an approximately hemispherical geometry. A particularly advantageous combustion chamber geometry can thus be achieved in respect of the cylinder head. Thus, the flow characteristics of the mixture during the intake process can be favorably influenced.

According to one embodiment, the active region of the combustion chamber ceiling is formed substantially without edges. The effective area of the combustion dome is the following area: which essentially forms the hemispherical geometry of the combustion dome. Due to the edgeless design of the combustion chamber roof, the tumble flow of the mixture is not disturbed in particular. Turbulent kinetic energy of the air-fuel mixture can thus be generated and optimally maintained during compression.

By means of the high turbulent kinetic energy, a high combustion speed can be achieved, so that the initial flame can propagate in the mixture particularly quickly. Furthermore, the high combustion speed results in the mixture present in the combustion chamber burning as completely as possible during the combustion cycle and hardly any unburned fuel remaining in the combustion chamber.

Overall, a particularly good thermodynamic efficiency and reduced fuel consumption are achieved by the internal combustion engine according to the invention.

Preferably, the combustion dome is completely machined. Reproducibility of the combustion dome is thus improved, since machining has less manufacturing error than casting. In particular, it is thus possible to form an effective region with little divergence, which is essentially edgeless, and which in turn leads to a hemispherical geometry.

Preferably, the piston has a recess, in particular a lens-shaped recess, which is rotationally symmetrical about the piston axis and whose diameter is smaller than the overall diameter of the piston. The recess allows the flow to develop optimally in order to generate a tumble flow movement in the combustion chamber (already during the inflow). In this regard, the recesses support the maintenance of turbulent kinetic energy at the moment of combustion. Furthermore, the recess has an effect on the combustion chamber, and thus on the compression ratio of the internal combustion engine, as does the combustion dome.

The recess of the piston preferably has a depth of between 0.2mm and 10mm, in particular between 0.5mm and 8mm, at the center point of the recess. Said depth has proven to be particularly advantageous in terms of aeration movement and flame propagation. In general, the depth of the recess is determined in accordance with a predetermined compression ratio of the internal combustion engine in conjunction with the combustion dome. The compression ratio corresponds to the ratio of the entire combustion chamber before compression when the piston is at bottom dead center to the remaining combustion chamber after compression when the piston is at top dead center.

The projected area of the recess preferably has an area fraction of 70% to 80% of the piston on the end face of the piston, i.e. on the combustion chamber side. This geometry ensures a correspondingly high surface portion of the recess and accordingly the influence of the recess on the entire combustion chamber.

The recess can enclose an approximately spherical space with the combustion dome, in particular with the active area of the combustion dome, which serves as a combustion chamber. This promotes flame propagation in the combustion chamber, which results in particularly efficient combustion.

According to one embodiment, the cylinder head has only on two edge sections lying opposite one another compression surfaces in the form of circular surface sections, which are each delimited by one of two transitions in the cylinder head running parallel to one another, the two compression surfaces having different surface sizes.

The spark plug is preferably arranged eccentrically in the cylinder head. Depending on the structure of the combustion chamber, in particular the arrangement of the valves in the cylinder head and the arrangement of the injectors. If air, or at least a mixture comprising air and fuel, flows into the combustion chamber via the intake valve, it generally accelerates towards the exhaust side of the combustion chamber.

A low flow velocity in the region of the spark plug is advantageous, since the initial flame can propagate particularly well at low flow velocities. Once the flow velocity is too high, the spark may be blown away and the corresponding flame extinguished, and therefore the mixture may not burn sufficiently or even at all, which adversely affects the efficiency of the combustion process.

The piston preferably has a piston pressing surface on its combustion chamber side corresponding to the cylinder head. In particular, the piston has two piston contact surfaces which are diametrically opposite one another with reference to the longitudinal piston axis. In an alternative embodiment, the piston compression surface may be smaller than the compression surface of the cylinder head. This corresponds to an increased diameter of the recess.

The piston contact surface is preferably formed in a partial circle, in particular in the shape of a circle segment or in the shape of an arc.

The piston pressure surface associated with the outlet side of the cylinder head is approximately equal in area to the corresponding pressure surface of the cylinder head. The piston compression surface associated with the inlet side of the cylinder head can be smaller in area than the corresponding compression surface of the cylinder head.

Preferably, a screen is arranged in the combustion chamber ceiling beside the valve seat parallel to the valve axis of the inlet valve, the screen having a height of between 2mm and 3.5 mm. By means of the screen, an overflow of the inlet valve occurs, which leads to a tumble motion of the mixture, in particular at small valve strokes. The turbulence level is increased by the tumble motion.

Preferably, the piston has at least two recesses on its combustion chamber side, which recesses are designed as valve bowls. The valve bowl serves as a mechanical safety to avoid collisions between the valve and the piston.

According to a preferred embodiment, two curved cylinder head sections are provided in the cylinder head, in particular in the combustion chamber ceiling, which are each arranged between two valve seats which are assigned to an intake valve and an exhaust valve. This results in a particularly advantageous combustion chamber configuration in terms of the combustion process, in particular in the form of a sphere. The two curved cylinder head sections are therefore both located between the intake side and the exhaust side of the cylinder head, so that the two curved cylinder head sections have approximately the same contribution to the improvement of the flow behavior.

Drawings

Other features and advantages of the present invention will become apparent from the ensuing description and the appended drawings to which reference is made. The attached drawings are as follows:

FIG. 1 schematically illustrates an internal combustion engine according to the present invention;

fig. 2 shows a combustion chamber space of an internal combustion engine according to the invention;

fig. 3 shows a sectional view of a piston of an internal combustion engine according to the invention;

FIG. 4 shows a perspective view of the piston of FIG. 3; and is

Fig. 5 shows a top view of a combustion chamber of an internal combustion engine according to the invention, wherein a piston associated with the combustion chamber is depicted in a transparent manner.

Detailed Description

Fig. 1 schematically shows an internal combustion engine 10 having a cylinder 12, a cylinder head 14, and a piston 16 movably mounted in the cylinder 12.

The piston 16 has a combustion chamber side 18 which, together with the cylinder head 14 and the cylinder 12, defines a combustion chamber 20 of the internal combustion engine 10, the cylinder head 14 having a combustion chamber roof 21 oriented towards the combustion chamber 20. In the cylinder head 14, in particular in the combustion chamber ceiling 21, valve seats 22, 24 for at least one intake valve 26 and exhaust valve 28 and a spark plug 30 are provided. The spark plug 30 is in particular arranged eccentrically.

The elements schematically depicted in fig. 1 are explained in detail in the following figures.

The general operating mode of an internal combustion engine is sufficiently known from the prior art, so that no further explanation is necessary here, since what is important in the following is the geometry of the cylinder head 14, in particular of the side of the cylinder head 14 oriented toward the combustion chamber 20.

Fig. 2 shows the combustion chamber space 31 of the internal combustion engine 10 according to the invention in a state in which the piston 16 is at top dead center. The combustion chamber space 31 is delimited by the cylinder head 14 (in particular the combustion chamber ceiling 21 of the cylinder head) together with the cylinder 12 and the piston 16.

Fig. 2 therefore shows essentially a negative diagram of the cylinder head 14 (in particular the combustion chamber ceiling 21 of the cylinder head) and of the piston 16.

The cylinder head 14 (in particular the combustion chamber ceiling 21) has a rounded outer geometry in top view and essentially five surfaces 32, 34, 36, 38, 40 angled to each other. The surfaces 38, 40 and 36, 40 are respectively rounded to one another in order to avoid sharp edges at the respective transitions of the surfaces 36-40 in the active region 41 of the combustion dome 21. The active area 41 of the combustion dome 21 preferably additionally comprises surfaces 36, 38, 40.

The surfaces 32, 34 arranged laterally to the cylinder head 14 are in each case pressure surfaces. The shape of the pressing surfaces 32, 34 corresponds to the shape of the circular segment, the pressing surfaces 32, 34 being each delimited toward the (radially) inner side by one of two transitions 42, 44 running parallel to one another, whereas the outer edges of the cylinder running surfaces delimit the pressing surfaces 32, 34 toward the (radially) outer side. The two pressing surfaces 32, 34 are therefore arranged in opposite edge sections of the cylinder head 14.

The transitions 42, 44 are each arranged between the pressing surfaces 32, 34 and the adjacent surfaces 36, 38, which extend from the pressing surfaces 32, 34 toward the center of the cylinder head 14 and are part of the active region 41. The transitions 42, 44 have different distances from the center point of the cylinder head 14.

In the illustrated embodiment, the contact surface 32 associated with the intake side, i.e., the intake valve 26, is larger in area than the contact surface 34 associated with the exhaust side, i.e., the contact surface 34 associated with the exhaust valve 28.

Between the valve seats 22, 24, in particular between in each case one valve seat 22 for the inlet valve 26 and one valve seat 24 for the outlet valve 28, in each case curved sections 46, 47 are provided in the cylinder head 14. The curved sections 46, 47 are also part of the active region 41 of the combustion chamber roof 21, and they are curved in such a way that their curvature is directed away from the combustion chamber 20.

By means of the curved sections 46, 47, in particular by means of their curvature, the combustion dome 21 can have a substantially hemispherical geometry. The propagation of the flame in the combustion chamber 20 is thus promoted, which in turn leads to thermodynamically optimized combustion, as will be explained later.

The cylinder head 14, in particular the combustion chamber ceiling 21, has a total of four valve seats 22, 24 for two intake valves 26 and two exhaust valves 28. In the combustion chamber ceiling 21, adjacent to the valve seat 22 of the intake valve 26, one screen 48 is arranged parallel to the valve axis, which has a height of between 2mm and 3.5 mm. The screen 48 ensures a tumbling movement of the mixture flowing in via the inlet valve 26, which leads to an increase in the turbulent kinetic energy of the mixture and thus to an increased combustion speed and optimized flame propagation.

Fig. 3 shows a cross-sectional view of a piston 16, which is produced, for example, in a die casting method.

A recess 50 is formed in the combustion chamber side 18 of the piston 16, which together with the cylinder 12 and the cylinder head 14 (in particular the combustion chamber roof 21) delimit the combustion chamber 20 of the internal combustion engine 10, said recess being rotationally symmetrical and lens-shaped. The recess 50 has a bottom surface 52 and a height h of between 0.5mm and 8 mm. The recess 50 of the piston 16 is rotationally symmetrical about a longitudinal axis 54.

The curvature of the recess 50, which is oriented in the opposite direction, corresponds, for example, substantially to the curvature of the curvature sections 46, 47 of the cylinder head 14. The combustion chamber 20 can therefore be designed as symmetrically as possible. By the interaction of the active region 41 (in particular the arcuate sections 46, 47) with the lens-shaped recess, the combustion chamber 20 is approximately spherical, which is optimized with regard to combustion.

The tumble flow generated when the mixture flows in is supported and maintained based on this geometry of the combustion chamber 20.

The diameter D of the recess 50 is smaller than the overall diameter D of the piston 16, so that a circumferential land 56 is formed, which radially surrounds the recess 50. A portion of the circumferential land 56 forms piston pressing surfaces 58, 60 of the piston 16, which are described in more detail in connection with fig. 4. The overall diameter D of the piston 16 is approximately equal to the inner diameter of the cylinder 12.

The compression ratio of the internal combustion engine 10 can be adjusted (additionally) via the depth of the recess 50 overall, as long as mechanical boundary conditions or mechanical limitations are taken into account, for example with regard to the stability of the piston 16.

Fig. 4 shows a perspective view of the piston 16. From this view, it can be seen that the piston 16 has, in addition to the recess 50 which is already visible in fig. 3, a recess 62 which is designed as a valve cup. The gap 62 serves as a mechanical fuse 64 to avoid collision of the valves 26, 28 with the piston 16.

Fig. 5 shows a combustion chamber 20, in particular a combustion chamber space 21, in a plan view, the piston 16 being illustrated in a transparent manner.

The piston pressure surfaces 58, 60 are oriented on the pressure surface 34 of the cylinder head 14 associated with the exhaust gas side, in particular the pressure surfaces 58, 60 at least partially cover the pressure surfaces 32, 34 of the cylinder head 14. In an alternative embodiment, the piston compression surfaces 58, 60 may be smaller in area than the compression surfaces 32, 34 of the cylinder head 14.

As already explained, not only the generated tumble flow but also the turbulent kinetic energy of the drawn-in mixture is maintained as long as possible on the basis of the geometry of the combustion chamber 20, so that a high combustion speed can be achieved, so that the initial flame starting from the spark plug 30 can propagate rapidly in the mixture. Thereby correspondingly increasing the efficiency of the internal combustion engine 10.

The geometry of the combustion chamber 20 required for this purpose is furthermore realized by an effective region 41 of the combustion chamber crown 21, which is formed essentially without edges and which interacts with a recess 50 in the piston 16.

In order to form the combustion dome 21 in this way, it is (merely) machined.