INTERNAL COMBUSTION ENGINE

Abstract

A cavity 40 of an internal combustion engine 1 comprises: a raised section 42 with a first inclined surface 43 inclined downwards from the radial center towards the radial outer side; a projection 45 arranged on the outer side of the raised section 42; and a connecting section 50 connecting the projection 45 and the raised section 42. The connecting section 50 comprises a second inclined surface 54 associated with a curved surface 52, the second inclined surface 54 being lower in the radial outer side; and a stepped section 56 formed between the second inclined surface 54 and the raised section 42, wherein an angle of the second inclined surface 54 with respect to an orthogonal plane perpendicular to the axial direction of the piston 30 is greater than an angle of the first inclined surface 43 with respect to the orthogonal plane.

Description

TECHNICAL AREA

[0001] The present disclosure relates to an internal combustion engine with a piston in which a cavity is formed. STATE OF THE ART

[0002] To mix fuel (unburned fuel) and air, the cavity of a piston, disclosed in Japanese patent application no. JP 2021-11843 A, is arranged with a stepped section for separating the fuel flowing along the curved section to the raised section in the middle. Brief description of the invention; task to be solved by the invention

[0003] However, with the technique described above, the fuel separated from the stage section easily comes into contact with the raised section before it mixes with the ambient air, resulting in insufficient air intake and reduced fuel-air mixing.

[0004] The present disclosure was made with these points in mind, and its purpose is to promote the mixing of fuel and air in a cavity. SOLUTION TO THE TASK

[0005] A first aspect of the present disclosure provides an internal combustion engine comprising: a piston with a cavity formed in a central section of its upper surface; and an injector injecting fuel into the cavity, the cavity comprising: a raised section with a first inclined surface inclined downwards in a radial direction from a radial center of the piston towards an outside surface; a projection arranged radially along a circumferential direction of the piston on an outside surface of the raised section;and a connecting section arranged to surround the raised section and to connect the projection and the raised section, the connecting section comprising a curved surface associated with the projection, a second inclined surface associated with the curved surface on an inside in a radial direction and inclined to become lower in a radial direction towards an outside, and a step section formed between the second inclined surface and the raised section, and an angle of the second inclined surface with respect to an orthogonal plane perpendicular to an axial direction of the piston being greater than an angle of the first inclined surface with respect to the orthogonal plane.

[0006] Furthermore, the second inclined surface can be a flat surface inclined at a given angle with respect to the orthogonal plane.

[0007] Furthermore, the step section can comprise a step surface inclined with respect to the second inclined surface, an upper end section connecting the step surface and the second inclined surface, and a lower end section connecting the step surface and the first inclined surface, and the lower end section can be arranged vertically below the upper end section.

[0008] Furthermore, a connecting section between the second inclined surface and the curved surface can be arranged in a vertical direction below the lower end section.

[0009] Furthermore, an imaginary line extending radially from the second inclined surface towards the inside along a surface of the second inclined surface can pass through the injector when the piston is at top dead center.

[0010] Furthermore, an imaginary line extending radially from the second inclined surface towards the inside can run along a surface of the second inclined surface between a vertex of the raised section and the injector.

[0011] Furthermore, the second inclined surface and the step section can be arranged along the circumferential direction.

[0012] Furthermore, a multitude of second inclined surfaces and a multitude of step sections can be arranged at predetermined intervals in the circumferential direction.

[0013] Furthermore, the step surface can be a flat surface perpendicular to the second inclined surface. IMPACT OF THE INVENTION

[0014] According to the present disclosure, an effect can be achieved to promote the mixing of fuel spray and air in a cavity. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic view showing an embodiment of an internal combustion engine 1 according to one embodiment. Fig. Figure 2 is a schematic view showing a cross-section of the design of a cavity 40. Fig. Figure 3 is a schematic view showing a state in which an injector 22 has sprayed fuel onto a projection 45. Fig. Figure 4 is a schematic view showing a condition in which the fuel flows along a second inclined surface 54. Fig. Figure 5 is a schematic view showing a state in which the fuel is separated from the top of the second inclined surface 54. DESCRIPTION OF EXAMPLES OF EXECUTION<Ausgestaltung eines Verbrennungsmotors>

[0015] Fig. Figure 1 is a schematic view showing an embodiment of an internal combustion engine 1 according to one embodiment. Here, the internal combustion engine 1 is mounted on a vehicle, such as a truck, but is not limited to this and can, for example, be mounted on a ship.

[0016] The internal combustion engine 1 is, for example, a diesel engine. The internal combustion engine 1 is a power source that generates power to cause a vehicle to move by burning and expanding an air-fuel mixture of intake air and fuel in a combustion chamber 2. The internal combustion engine 1 comprises a cylinder block 10, a cylinder head 20, a piston 30, and a crankshaft 60.

[0017] The cylinder block 10 comprises a cylinder 12 in which the piston 30 is housed in such a way that the piston 30 can move back and forth, and a crankcase 16 in which the crankshaft 60 is housed. An oil pan 18, which stores lubricating oil, is attached to the crankcase 16.

[0018] The cylinder head 20 is located on an upper section of the cylinder block 10. The cylinder head 20 comprises an injector 22, an inlet valve 25, and an exhaust valve 26. The injector 22 injects fuel into the combustion chamber 2, which is defined by the top of the piston 30, an inner wall surface 13 of the cylinder 12, and the cylinder head 20. The inlet valve 25 opens and closes to introduce intake air (air) from an inlet port 23 into the combustion chamber 2. The exhaust valve 26 opens and closes to direct the exhaust gas from the combustion chamber 2 into the exhaust port 24.

[0019] The piston 30 moves back and forth within the cylinder 12. As the piston 30 moves between top dead center and bottom dead center, it slides on the inner wall surface 13 of the cylinder 12. Lubricating oil is supplied to the inner wall surface 13 to form an oil film. Because the oil film is formed on the inner wall surface 13, the frictional force is reduced as the piston 30 slides on the inner wall surface 13.

[0020] A top surface 31 of the piston 30 has a cavity 40 (see Fig. 2) The cavity 40 is formed by recessing the upper surface 31 and forms part of the combustion chamber 2. When the piston 30 is, for example, near top dead center, the injector 22 injects fuel into the cavity 40. The fuel injected into the cavity 40 mixes with air in the cavity 40 and combusts. A detailed design of the piston 30 will be described later.

[0021] The crankshaft 60 is coupled to the piston 30 via a connecting rod (hereinafter referred to as "connecting rod") 62. The crankshaft 60 converts the reciprocating motion of the piston 30 into a rotary motion. <Detaillierte Ausgestaltung des Hohlraums>

[0022] Fig. Figure 2 is a schematic view showing a cross-section of the design of the cavity 40. The in Fig. The vertical direction shown in Figure 2 is parallel to the axial direction of piston 30. Furthermore, the vertical direction is parallel to the up-down direction. Fig. Figure 2 shows piston 30, which is positioned near top dead center.

[0023] The cavity 40 is formed by deepening the central section of the upper surface 31 of the piston 30. As shown in Fig. As shown in Figure 2, the cavity 40 comprises a raised section 42, a projection 45 and a connecting section 50.

[0024] The raised section 42 is a section that extends from the bottom section of the cavity 40 towards the injector 22. For example, the raised section 42 is conically shaped. The raised section 42 is located on the radial center section of the piston 30. The raised section 42 faces the injector 22 when the piston 30 is at top dead center. The apex of the raised section 42 and the injector 22 are positioned on the central axis C of the piston 30.

[0025] The raised section 42 has a first inclined surface 43. The first inclined surface 43 is inclined downwards in the vertical direction from the apex (the radial center of the piston 30) of the raised section 42 towards the radial outer side. The first inclined surface 43 is, for example, a flat surface inclined at a predetermined angle. Here, as in Fig. 2 shown, the angle of the first inclined surface 43 with respect to an orthogonal plane D, which is perpendicular to the axial direction of the piston 30, is assumed to be angle α1.

[0026] The projection 45 extends vertically upwards at a position outside the raised section 42 in the radial direction of the piston 30. The projection 45 is located closer to the top surface 31 of the piston 30 than the raised section 42 within the cavity 40. Specifically, the projection 45 is positioned vertically above the apex of the raised section 42. It should be noted that the vertical relationship between the projection 45 and the raised section 42 can be suitably varied depending on the specifications required for the internal combustion engine 1. The projection 45 is also arranged along the circumferential direction of the piston 30. In this case, the projection 45 is continuous around the entire circumference to surround the raised section 42 circumferentially.

[0027] As in Fig. As shown in Figure 2, injector 22 sprays fuel in the direction of projection 45. Injector 22 has a plurality of injection holes arranged at predetermined intervals in the circumferential direction, and each injection hole sprays fuel. Fig. Figure 2 shows, for the sake of simplicity, only the fuel injection direction through one injection hole. The fuel injected by injector 22 (especially the fuel spray) is deflected by the projection 45. Part of the deflected fuel flows towards the connecting section 50, as indicated by arrow A1. Fig. 2 is shown, while the remaining fuel flows outwards in a radial direction from cavity 40, as indicated by arrow A2.

[0028] The connecting section 50 is arranged radially along the piston 30 between the raised section 42 and the projection 45, connecting the projection 45 and the raised section 42. The connecting section 50 is arranged vertically below the projection 45. The connecting section 50 is positioned at a location corresponding to the projection 45 in the circumferential direction. The projection 45 is arranged to surround the raised section 42 in the circumferential direction, and the connecting section 50 is also arranged to surround the raised section 42. Here, the connecting section 50 is arranged along the circumferential direction of the piston 30. A portion of the fuel deflected by the projection 45 (unburned fuel) flows along the connecting section 50 toward the center of the cavity 40.

[0029] As in Fig. As shown in Figure 2, the connecting section 50 has a curved surface 52, a second inclined surface 54, and a stepped section 56. The curved surface 52 is a section of the connecting section 50 located on the radially outer side of the piston 30 and is connected to the projection 45. The curved surface 52 acts as a guide surface, directing the fuel deflected by the projection 45 toward the center of the cavity 40. Here, the curved surface 52 is curved with a predetermined curvature to facilitate the flow of fuel toward the center of the cavity 40.

[0030] The curved surface 52 is arranged along the circumferential direction. The curved surface 52 extends continuously around its entire circumference to surround the raised section 42. Accordingly, even if the fuel is deflected by the projection 45 and spreads circumferentially, it can flow more easily along the curved surface 52, thus facilitating its flow towards the center of the cavity 40.

[0031] The second inclined surface 54 is arranged on the inner (central) side of the curved surface 52 in the radial direction of the piston 30. Specifically, the second inclined surface 54 is located between the curved surface 52 and the step section 56 in the radial direction of the piston 30. One end of the second inclined surface 54 is connected to the curved surface 52, and the other end of the second inclined surface 54 is connected to the step section 56. Similar to the curved surface 52, the second inclined surface 54 is arranged circumferentially. Similarly to the curved surface 52, the second inclined surface 54 extends continuously around the entire circumference in the circumferential direction. Starting from the curved surface 52, the second inclined surface 54 directs the fuel towards the center of the cavity 40.

[0032] The second inclined surface 54 is inclined towards the injector 22. Specifically, the second inclined surface 54 is inclined such that a connecting section (one end of the second inclined surface 54) with the curved surface 52 is arranged vertically below a connecting section (the other end of the second inclined surface 54) with the step section 56. The second inclined surface 54 is inclined between the curved surface 52 and the step section 56 such that it decreases in height towards the radial outer side. The second inclined surface 54 is a planar surface inclined at a predetermined angle α2 with respect to the orthogonal plane D, which is perpendicular to the axial direction of the piston 30. Because the second inclined surface 54 is inclined in this way, the fuel flowing along the second inclined surface 54 can flow directly towards the radial central section and vertically upwards.

[0033] The angle α2 of the second inclined surface 54 with respect to the orthogonal plane D is larger than the angle α1 of the first inclined surface 43 with respect to the orthogonal plane D. That is, the second inclined surface 54 is a surface that is steeper than the first inclined surface 43. Accordingly, the fuel separated from the second inclined surface 54 can more easily draw in air around the first inclined surface 43 while being separated from it. As a result, the mixing of fuel and air is promoted.

[0034] The step section 56 is a section that forms a step between the raised section 42 and the connecting section 50. The step section 56 is formed between the raised section 42 and the second inclined surface 54. Specifically, the step section 56 is formed between the first inclined surface 43 and the second inclined surface 54 of the raised section 42. The step section 56 is arranged circumferentially. The step section 56 is arranged continuously around the entire circumference. The provision of the step section 56 allows the fuel flowing along the second inclined surface 54 to be more easily separated at the step section 56. In other words, the fuel flowing along the second inclined surface 54 can be more easily separated at the step section 56 from the surface forming the cavity 40.

[0035] The step section 56 has a step surface 57, an upper end section 64, and a lower end section 65. The step surface 57 is a surface inclined with respect to the second inclined surface 54. The upper end section 64 is a section that connects the step surface 57 and the second inclined surface 54 at one end (upper end) of the step surface 57. The lower end section 65 is a section that connects the step surface 57 and the first inclined surface 43 at the other end (lower end) of the step surface 57. The step surface 57 is, for example, a flat surface perpendicular to the second inclined surface 54. In this embodiment, the upper end section 64 forms a corner, so that the fuel flowing along the second inclined surface 54 is more easily separated at the upper end section 64 from the surface forming the cavity 40.The fuel flowing along the connecting section 50 travels straight towards the radial central section and vertically upwards as it flows along the second inclined surface 54. The fuel flowing along the second inclined surface 54 continues straight, without changing direction, even after passing the upper end section 64. Therefore, at the upper end section 64, where the second inclined surface 54 and the step surface 57 are joined, the fuel flowing along the second inclined surface 54 separates from the surface forming the cavity 40 and continues on its course.

[0036] The lower end section 65 of the step section 56, which is connected to the first inclined surface 43, is arranged vertically below the upper end section 64 of the step section 56, which is connected to the second inclined surface 54. In the above description, the step surface 57 is a flat surface, but is not limited to this, and the step surface 57 can be a curved surface.

[0037] The connecting section, where the second inclined surface 54 and the curved surface 52 are connected, can be arranged vertically below the lower end section 65, which connects the stepped section 56 (the stepped surface 57) and the first inclined surface 43. In this case, the depth of the raised section 42 from the top 31 of the piston 30 can be reduced, thereby decreasing the volume of the cavity 40, which is the recessed section. As a result, the compression ratio during the compression stroke of the internal combustion engine 1 can be increased.

[0038] The second inclined surface 54 is arranged such that an imaginary line B, which extends from the one in Fig. The imaginary line B extends from the second inclined surface 54, shown in Figure 2, across the apex of the raised section 42. This imaginary line extends from the second inclined surface 54 towards the radial inside (center) of the piston 30 along the surface of the second inclined surface 54. Specifically, the imaginary line B extending from the second inclined surface 54 passes between the apex of the raised section 42 and the injector 22. Consequently, the separated fuel can more easily flow away from the first inclined surface 43 of the raised section 42, allowing the fuel to draw in air around the first inclined surface 43 and thus promoting the mixing of fuel and air. It should be noted that the imaginary line B extending from the second inclined surface 54 can pass through the injector 22 when the piston 30 is at top dead center.

[0039] Here, the flow of the fuel injected by injector 22 into cavity 40 is described with reference to the Fig. 3, Fig. 4 to Fig. 5 described. Fig. Figure 3 is a schematic view showing the state immediately after injector 22 has sprayed fuel onto protrusion 45. Fig. Figure 4 is a schematic view showing the state in which the fuel flows along the second inclined surface 54. Fig. Figure 5 is a schematic view showing the state in which the fuel is separated from the surface forming the cavity 40 at the upper end section 64. Fig. Figure 3 shows piston 30, which is positioned near top dead center, and the Fig. 4 and Fig. Figure 5 shows the state in which the piston 30 is moving towards bottom dead center.

[0040] Here, it is assumed that injector 22 sprayed fuel when piston 30 was near top dead center. As in Fig. As shown in Figure 3, injector 22 sprays fuel towards projection 45. The injected fuel strikes projection 45 and is deflected. Part of the deflected fuel flows over projection 45 towards the outside in a radial direction, while the remaining fuel flows onto the curved surface 52 of connecting section 50.

[0041] After injector 22 has sprayed the fuel, piston 30 moves towards bottom dead center. At this point, as in Fig. As shown in Figure 4, the fuel, which has flowed from the projection 45 onto the curved surface 52, flows along the second inclined surface 54 in continuation of the curved surface 52. By flowing along the second inclined surface 54, the flow direction of the fuel becomes straight. In particular, the fuel flows directly along the second inclined surface 54 in the direction of the radial central section and vertically upwards.

[0042] As piston 30 continues to move towards bottom dead center, as in Fig.As shown in Figure 5, the fuel flowing along the second inclined surface 54 separates at the upper end section 64, which is connected to the stepped surface 57 of the second inclined surface 54, from the surface forming the cavity 40. Since the fuel flows directly along the second inclined surface 54, it separates more readily. In contrast to the present embodiment, if the curved surface 52 is directly connected to the stepped surface 57 without the second inclined surface 54, the fuel flow direction is not straight, making separation less likely. Furthermore, even if the fuel does separate, its flow direction is not straight, making it more likely that the fuel will come into contact with the raised section 42.

[0043] The separated fuel does not contact the raised section 42 (in particular the first inclined surface 43) and flows away from the first inclined surface 43. At this point, the fuel draws in ambient air and combusts. Since there is a space between the flowing fuel and the first inclined surface 43, air is easily drawn from this space into the fuel, thus promoting fuel combustion. <abwandlung>

[0044] In the description above, the stepped section 56 and the second inclined surface 54 are arranged continuously around the raised section 42 along the circumferential direction over the entire circumference. However, the present embodiment is not limited to this. For example, a plurality of stepped sections 56 and a plurality of second inclined surfaces 54 are arranged at predetermined intervals in the circumferential direction. In particular, the stepped section 56 and the second inclined surface 54 are arranged in the circumferential direction corresponding to the positions of the plurality of injection holes of the injector 22. Even in this case, it is likely that the fuel injected from each injection hole of the injector 22 and flowing along the connecting section 50 will separate at the upper end section 64.

[0045] In the description above, the second inclined surface 54 is a flat surface, but its design is not limited to this. For example, the second inclined surface 54 can be a curved surface. Likewise, the first inclined surface 43 can also be a curved surface. <Wirkungen der Ausführungsform>

[0046] The cavity 40 of the piston 30 of the embodiment described above comprises: the raised section 42 with the first inclined surface 43; the projection 45, which is arranged along the circumferential direction of the piston 30 on the outside of the raised section 42; and the connecting section 50, which is arranged to surround the raised section 42 and connect the projection 45 and the raised section 42. The connecting section 50 comprises: the curved surface 52, which is associated with the projection 45; the second inclined surface 54, which is associated with the curved surface 52 on the radial inside and is inclined such that it becomes lower towards the radial outside; and the stepped section 56, which is formed between the second inclined surface 54 and the raised section 42.The angle α2 of the second inclined surface 54 with respect to the orthogonal plane D, which is perpendicular to the axial direction of the piston 30, is greater than the angle α1 of the first inclined surface 43 with respect to the orthogonal plane D. The provision of the second inclined surface 54 described above allows the fuel, which has flowed along the second inclined surface 54 and along the curved surface 52, to separate more easily at the upper end section 64, which connects the second inclined surface 54 and the step section 56. Furthermore, since the angle of inclination α2 of the second inclined surface 54 is greater than the angle of inclination α1 of the first inclined surface 43, the separated fuel is less likely to come into contact with the first inclined surface 43, thus allowing the fuel to draw in ambient air.As a result, the mixing of the separated fuel and air is promoted, thereby increasing the efficiency of combustion.

[0047] The present disclosure is explained with reference to the exemplary embodiments. The technical scope of the present disclosure is not limited to that described in the embodiments above, and it is possible to make various changes and modifications within the scope of the disclosure. For example, all or part of the device may be configured with any unit that is functionally or physically distributed or integrated. Furthermore, new exemplary embodiments generated by any combination thereof are included in the exemplary embodiments. Moreover, effects of the new exemplary embodiments brought about by the combinations also exhibit the effects of the original exemplary embodiments. REFERENCE MARK LIST 1 Internal combustion engine 22 injectors 30 pistons 40 cavity 42 elevated section 43 first inclined surface 45 lead 50 connecting section 52 curved surface 54 second inclined surface 56th stage section QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2021-11843 A

[0002] < / abwandlung>

Claims

Internal combustion engine (1), comprising: a piston (30) with a cavity (40) formed in a central section of a top surface thereof; and an injector (22) injecting fuel into the cavity (40), wherein: the cavity (40) comprises: a raised section (42) with a first inclined surface (43) inclined downwards in a radial direction from a radial center of the piston (30) to an outside surface; a projection (45) arranged radially along a circumferential direction of the piston (30) on an outside surface of the raised section (42);and a connecting section (50) arranged to surround the raised section (42) and to connect the projection (45) and the raised section (42), the connecting section (50) comprising: a curved surface (52) associated with the projection (45), a second inclined surface (54) associated with the curved surface (52) on an inner side in a radial direction and inclined such that it becomes lower towards an outer side in a radial direction, and a step section (56) formed between the second inclined surface (54) and the raised section (42), wherein an angle of the second inclined surface (54) with respect to an orthogonal plane perpendicular to an axial direction of the piston (30) is greater than an angle of the first inclined surface (43) with respect to the orthogonal plane. Internal combustion engine (1) according to claim 1, wherein the second inclined surface (54) is a planar surface inclined at a predetermined angle with respect to the orthogonal plane. Internal combustion engine (1) according to claim 1 or 2, wherein the stage section (56) comprises a stage surface (57) inclined with respect to the second inclined surface (54), an upper end section (64) connecting the stage surface (57) and the second inclined surface (54), and a lower end section (65) connecting the stage surface (57) and the first inclined surface (43), and the lower end section (65) is arranged in a vertical direction below the upper end section (64). Internal combustion engine (1) according to one of claims 1 to 3, wherein a connecting section between the second inclined surface (54) and the curved surface (52) is arranged in a vertical direction below the lower end section (65). Internal combustion engine (1) according to one of claims 1 to 4, wherein an imaginary line extending from the second inclined surface (54) towards the inside in a radial direction along a surface of the second inclined surface (54) passes through the injector (22) when the piston (30) is at top dead center. Internal combustion engine (1) according to one of claims 1 to 4, wherein an imaginary line extending radially from the second inclined surface (54) towards the inside runs along a surface of the second inclined surface (54) between a vertex of the raised section (42) and the injector (22). Internal combustion engine (1) according to one of claims 1 to 6, wherein the second inclined surface (54) and the step section (56) are arranged along the circumferential direction. Internal combustion engine (1) according to one of claims 1 to 6, wherein a plurality of second inclined surfaces (54) and a plurality of step sections (56) are arranged at predetermined intervals in the circumferential direction. Internal combustion engine (1) according to claim 3, wherein the step surface (57) is a flat surface perpendicular to the second inclined surface (54).

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