INTERNAL COMBUSTION ENGINE

Abstract

A piston of an internal combustion engine 1 has a cavity 40 comprising: a raised section 42 located in a central section, a projection 45 arranged along a circumferential direction of the piston 30 on an outer surface 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 curved surface 52 associated with the projection 45, a flat surface 54 associated with the curved surface 52 on the radial inner surface, and a stepped section 56 formed between the flat surface 54 and the raised section 42. The flat surface 54 is inclined between a connection point with the curved surface 52 and the stepped section 56 such that it becomes lower towards the radial outer surface.

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] One 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 arranged radially in a central section of the piston; a projection arranged radially along a circumferential direction of the piston on an outer 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 flat surface associated with the curved surface on an inside in a radial direction, and a step section formed between the flat surface and the raised section, the flat surface between the curved surface and the step section being inclined such that it becomes lower towards an outside in a radial direction.

[0006] Furthermore, an imaginary line extending radially from the flat surface towards the inside can run along a surface of the flat surface between a vertex of the raised section and the injector.

[0007] Furthermore, the raised section can have an inclined surface that is inclined radially outwards from a vertex of the raised section, and the step section can be formed between the inclined surface and the flat surface.

[0008] Furthermore, the step section can comprise a step surface inclined with respect to the flat surface, an upper end section connecting the step surface and the flat surface, and a lower end section connecting the step surface and the inclined surface, and the lower end section can be arranged vertically below the upper end section.

[0009] Furthermore, the flat surface can be parallel to the inclined surface. Furthermore, the flat surface and the stepped section can be arranged along the circumferential direction.

[0010] Furthermore, a large number of flat surfaces and a large number of step sections can be arranged at predetermined intervals in the circumferential direction.

[0011] Furthermore, the width of the flat surface in the radial direction can be longer than the width of the curved surface in the radial direction.

[0012] Furthermore, the apex of the raised section can be located vertically below the projection. IMPACT OF THE INVENTION

[0013] According to the present disclosure, an effect can be achieved to promote the mixing of fuel 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 state in which the fuel flows along a flat surface 54. Fig. Figure 5 is a schematic view showing a state in which the fuel is separated from the top of the flat surface 54. Fig. Figure 6 is a schematic view showing a modification of a cross-section of the design of a cavity 40. DESCRIPTION OF THE EXECUTION FORMS<Ausgestaltung eines Verbrennungsmotors>

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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>

[0021] 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 top-bottom direction is parallel to the vertical direction. Fig. Figure 2 shows piston 30, which is positioned near top dead center.

[0022] 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.

[0023] 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 is positioned on the central axis C of the piston 30 and the injector 22.

[0024] The raised section 42 has an inclined surface 43. The inclined surface 43 is inclined downwards in the vertical direction from the vertex of the raised section 42 towards the radial outer surface. The inclined surface 43 is, for example, a planar surface inclined at a predetermined angle. However, the present disclosure is not limited to this, and the inclined surface 43 can be a curved surface.

[0025] 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 upper surface 31 of the piston 30 than the raised section 42 is within the cavity 40.

[0026] In particular, the projection 45 is arranged 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 arranged along the circumferential direction of the piston 30. Here, the projection 45 is arranged continuously 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 flat surface 54, and a stepped section 56. The curved surface 52 is a section of the connecting section 50 located on the outside in the radial direction 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 flat surface 54 is arranged on the inner (central) side of the curved surface 52 in the radial direction of the piston 30. Specifically, the flat 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 flat surface 54 is connected to the curved surface 52, and the other end of the flat surface 54 is connected to the step section 56. Similar to the curved surface 52, the flat surface 54 is arranged circumferentially. Similarly to the curved surface 52, the flat surface 54 extends continuously around the entire circumference in the circumferential direction. Starting from the curved surface 52, the flat surface 54 directs the fuel towards the center of the cavity 40.

[0032] The flat surface 54 is inclined at a predetermined angle in the radial direction. The flat surface 54 is inclined such that a connecting section (one end of the flat surface 54) with the curved surface 52 is arranged vertically below a connecting section (the other end of the flat surface 54) with the stepped section 56. The flat surface 54 is inclined between the curved surface 52 and the stepped section 56 such that it becomes lower towards the radial outer side. Here, the flat surface 54 is parallel to the inclined surface 43 of the raised section 42. However, the present embodiment is not limited to this, and the flat surface 54 need not be parallel to the inclined surface 43. Because the flat surface 54 is inclined in this way, the fuel flowing along the flat surface 54 can flow straight along the radial central section and vertically upwards.

[0033] 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 flat surface 54. Specifically, the step section 56 is formed between the inclined surface 43 and the flat 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 flat surface 54 to be more easily separated at the step section 56. In other words, the fuel flowing along the flat surface 54 can be more easily separated at the step section 56 from the surface forming the cavity 40.

[0034] 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 flat surface 54 and is, for example, a flat surface perpendicular to the flat surface 54. The upper end section 64 is a section that connects the step surface 57 and the flat surface 54 at one end (upper end) of the step surface 57. Since the step surface 57 is perpendicular to the flat surface 54, the upper end section 64 forms a corner section. The lower end section 65 is a section that connects the step surface 57 and the inclined surface 43 at the other end (lower end) of the step surface 57. The fuel flowing along the flat surface 54 is more easily separated from the surface forming the cavity 40 at the upper end section 64, which is the corner section.The fuel flowing along the connecting section 50 travels straight towards the radial central section and vertically upwards as it flows along the flat surface 54. The fuel flowing along the flat surface 54 continues straight, without changing direction, even after passing the upper end section 64. Therefore, at the upper end section 64, where the flat surface 54 and the stepped surface 57 are joined, the fuel flowing along the flat surface 54 separates from the surface forming the cavity 40 and continues its course.

[0035] The lower end section 65 of the step section 56, which is connected to the inclined surface 43, is arranged vertically below the upper end section 64 of the step section 56, which is connected to the flat 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.

[0036] The flat surface 54 is arranged such that an imaginary line B, which extends from the in Fig. The imaginary line B extends from the flat surface 54 shown in Figure 2, passing over the apex of the raised section 42. This imaginary line extends from the flat surface 54 towards the radial inner (central) side of the piston 30 along the surface of the flat surface 54. Specifically, the imaginary line B extending from the flat 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 inclined surface 43 of the raised section 42, allowing the fuel to draw in air around the inclined surface 43 and thus promoting the mixing of fuel and air. It should be noted that the imaginary line B extending from the flat surface 54 can pass through the injector 22 when the piston 30 is at top dead center.

[0037] 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 flat 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.

[0038] 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.

[0039] 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 flat surface 54 in continuation of the curved surface 52. By flowing along the flat surface 54, the flow direction of the fuel becomes straight. In particular, the fuel flows directly along the flat surface 54 in the direction of the radial central section and vertically upwards.

[0040] As piston 30 continues to move towards bottom dead center, as in Fig. As shown in Figure 5, the fuel flowing along the flat surface 54 separates at the upper end section 64, which is connected to the stepped surface 57 of the flat surface 54, from the surface forming the cavity 40. Since the fuel flows directly along the flat 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 flat 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.

[0041] The separated fuel does not contact the raised section 42 (in particular the inclined surface 43) and flows away from the 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 inclined surface 43, air is easily drawn from this space into the fuel, thus promoting fuel combustion. <abwandlung>

[0042] Fig. Figure 6 is a schematic view showing a modified example of the cross-section of the cavity 40. In this modification, the width L1 of the flat surface 54 is radially longer than the width L2 of the curved surface 52. With the longer width L1 of the flat surface 54, as described above, a straight flow of fuel along the flat surface 54 is more easily formed, which causes the fuel to separate more readily at the upper end section 64.

[0043] At the in Fig. In the modification shown in Figure 6, increasing the width L1 of the flat surface 54 in the radial direction reduces the width of the inclined surface 43 in the radial direction. Furthermore, in this modification, because the length between the upper end section 64 and the lower end section 65 of the stepped surface 57 is reduced, the angle of inclination of the inclined surface 43 connected to the lower end section 65 is also reduced. As a result, the volume of the cavity 40, which is the recessed section, can be reduced, and thus the compression ratio during the compression stroke of the internal combustion engine 1 can be increased.

[0044] In the description above, the stepped section 56 and the flat surface 54 are arranged continuously around the raised section 42 along the circumferential direction over the entire circumference, but the present embodiment is not limited to this. For example, a plurality of stepped sections 56 and a plurality of flat surfaces 54 are arranged at predetermined intervals in the circumferential direction. In particular, the stepped section 56 and the flat 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. <Wirkungen der Ausführungsform>

[0045] The cavity 40 of the piston 30 of the embodiment described above comprises: the raised section 42, which is arranged on the radial central section of the piston 30; the projection 45, which is arranged along the circumferential direction 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 flat surface 54, which is associated with the curved surface 52 on the radial inner side; and the stepped section 56, which is formed between the flat surface 54 and the raised section 42. The flat surface 54 is inclined between the curved surface 52 and the stepped section 56 such that it becomes lower in the direction of the radial outer side.The provision of the flat surface 54 described above allows the fuel, which has flowed along the flat surface 54 and the curved surface 52, to separate more easily at the upper end section 64, which connects the flat surface 54 and the stepped section 56. Furthermore, by angling the flat surface 54 so that it recedes from the bottom section of the cavity 40, the separated fuel is less likely to come into contact with the raised section 42, and ambient air is drawn in more easily. As a result, the mixing of the separated fuel and air is promoted, thereby increasing the combustion efficiency.

[0046] 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 inclined surface 45 lead 50 connecting section 52 curved surface 54 flat 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 an upper surface thereof; and an injector (22) injecting fuel into the cavity (40), the cavity (40) comprising: a raised section (42) arranged radially in a central section of the piston (30); a projection (45) arranged radially along a circumferential direction of the piston (30) on an outer 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 flat surface (54) associated with the curved surface (52) on an inside in a radial direction, and a step section (56) formed between the flat surface (54) and the raised section (42), and the flat surface (54) between the curved surface (52) and the step section (56) being inclined such that it becomes lower in a radial direction towards an outside. Internal combustion engine (1) according to claim 1, wherein an imaginary line extending radially from the planar surface (54) towards the inside along a surface of the planar surface (54) between a vertex of the raised Internal combustion engine (1) according to claim 1 or 2, wherein the raised section (42) has an inclined surface (43) which is inclined radially outwards from a vertex of the raised section (42), and the step section (56) is formed between the inclined surface (43) and the flat surface (54). Internal combustion engine (1) according to claim 3, wherein the stage section (56) comprises a step surface (57) inclined with respect to the flat surface (54), an upper end section (64) connecting the step surface (57) and the flat surface (54), and a lower end section (65) connecting the step surface (57) and the 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 claim 3 or 4, wherein the flat surface (54) is parallel to the inclined surface (43). Internal combustion engine (1) according to one of claims 1 to 5, wherein the flat surface (54) and the step section (56) are arranged along the circumferential direction. Internal combustion engine (1) according to one of claims 1 to 5, wherein a plurality of flat surfaces (54) and a plurality of step sections (56) are arranged at predetermined intervals in the circumferential direction. Internal combustion engine (1) according to one of claims 1 to 7, wherein a width of the flat surface (54) in the radial direction is longer than a width of the curved surface (52) in the radial direction. Internal combustion engine (1) according to claim 2, wherein the apex of the raised section (42) is arranged in a vertical direction below the projection (45).

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