Internal combustion engine

Abstract

Invention details;

Description

internal combustion engine

[0001] The present invention relates to an internal combustion engine.

[0002] For example, Japanese Patent Publication No. 2011-502226 discloses an internal combustion engine including a cylinder, a piston, a cylinder head, and a fuel injection device. A piston bowl is provided on the upper surface of the piston. The piston bowl has an outer bowl portion that opens upward and protrusions that are evenly distributed around the circumference of the outer bowl portion.

[0003] Special Publication No. 2011-502226

[0004] In the internal combustion engine described in JP 2011-502226 A, flames that collide with adjacent portions of the outer bowl section in the circumferential direction across a protrusion tend to be directed toward the center of the combustion chamber by the protrusion. At this time, adjacent flames across the protrusion may interfere with each other, causing the flames to stagnate near the outer bowl section. In this case, utilization of air in the center of the combustion chamber is not promoted, resulting in reduced combustion efficiency.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide an internal combustion engine that allows for improved combustion in the combustion chamber.

[0006] an intake valve that opens and closes the intake port; an exhaust valve that opens and closes the exhaust port; a piston that is movable relative to the cylinder liner in a central axial direction of the cylinder liner and has a cavity formed at a position facing the cylinder head; and an injector that injects fuel from the cylinder head toward the cavity, wherein the cylinder head and the intake valve are configured to form a swirl flow in a combustion chamber formed between the cylinder head and the piston, and the injector injects the fuel from a center of the combustion chamber outward in a radial direction of the cylinder liner, and the piston injects fuel from the injector toward the cavity. The combustion chamber includes a peripheral wall formed at a position where it collides with a flame formed by ignition of the injected fuel and having a shape that continues in the circumferential direction of the cylinder liner, and a plurality of protruding walls provided at intervals in the circumferential direction of the peripheral wall, each having a shape that protrudes from the peripheral wall toward the center of the combustion chamber, wherein the protruding walls have a directly opposed surface that faces the swirl flow in the flow direction of the swirl flow and guides the flame that collides with the peripheral wall to the center of the combustion chamber, and a reversed surface that faces the swirl flow in the opposite direction to the flow direction of the swirl flow, and the directly opposed surface is configured so that the momentum of the flame that returns to the center of the combustion chamber via the directly opposed surface after colliding with the peripheral wall is greater than the momentum of the flame that returns to the center of the combustion chamber via the reversed surface after colliding with the peripheral wall.

[0007] According to the present invention, it is possible to provide an internal combustion engine that is capable of improving combustion in the combustion chamber.

[0008] It is a plan view which shows the internal combustion engine in one embodiment of the present invention. It is a cross-sectional view taken along the line II-II in Figure 1. It is a perspective view of a cavity of a piston. It is a plan view which shows the cavity. It is an enlarged view of the vicinity of a protruding wall.

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the accompanying drawings, in which the same or corresponding elements are designated by the same reference numerals.

[0010] Fig. 1 is a plan view that schematically shows an internal combustion engine according to one embodiment of the present invention. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. As shown in Figs. 1 and 2, the internal combustion engine 1 includes a cylinder liner 100, a cylinder head 200, an intake valve 300, an exhaust valve 400, a piston 500, and an injector 600. Although Figs. 1 and 2 show only one cylinder, the internal combustion engine 1 can also be applied to a multi-cylinder type.

[0011] The cylinder liner 100 is formed in a cylindrical shape. The cylinder head 200 is connected to one end of the cylinder liner 100. The cylinder head 200 is formed in a disk shape. The cylinder head 200 has an intake port h1 and an exhaust port h2.

[0012] The intake valve 300 opens and closes the intake port h1 and is held by the cylinder head 200.

[0013] The exhaust valve 400 opens and closes the exhaust port h2 and is held by the cylinder head 200.

[0014] The piston 500 is movable relative to the cylinder liner 100 along the central axis of the cylinder liner 100 (the up-down direction in FIG. 2 ). As shown in FIG. 2 , the piston 500 has a cavity CA formed in a position facing the cylinder head 200. The cavity CA has a shape that is recessed from a top surface 504 of the piston 500 in a direction away from the cylinder head 200 (downward in FIG. 2 ). A combustion chamber is formed between the piston 500, including the cavity CA, and the cylinder head 200. The piston 500 has a partition wall 502 that partitions the cavity CA.

[0015] The cylinder head 200 and the intake valve 300 are configured to form a swirl flow SW (see FIG. 3) in the combustion chamber.

[0016] The injector 600 is provided in the cylinder head 200 at a position facing the central axis of the cylinder liner 100. The injector 600 injects fuel from the cylinder head 200 toward the cavity CA. More specifically, the injector 600 injects fuel from the center of the combustion chamber outward in the radial direction of the cylinder liner 100.

[0017] Here, the partition wall 502 of the piston 500 will be described in detail with reference to Figures 3 and 4. Figure 3 is a perspective view of the cavity of the piston. Figure 4 is a plan view schematically showing the cavity. As shown in Figures 2 to 4, the partition wall 502 has a bottom wall 510, a peripheral wall 520, and a plurality of protruding walls 530.

[0018] The bottom wall 510 faces the injector 600 in the central axis direction of the cylinder liner 100. As shown in Fig. 2, the bottom wall 510 has a shape that slopes gradually away from the cylinder head 200 from the central portion facing the injector 600 in the central axis direction toward the outer side in the radial direction.

[0019] The peripheral wall 520 has a shape that rises from the edge of the bottom wall 510. The peripheral wall 520 has a shape that continues in an annular shape in the circumferential direction of the cylinder liner 100. The peripheral wall 520 is formed at a position where it collides with a flame B that is formed by ignition of fuel injected from the injector 600. As shown in Figures 2 and 3, the peripheral wall 520 has a shape that is curved so as to be convex outward in the radial direction.

[0020] Each protruding wall 530 has a shape that protrudes from the peripheral wall 520 toward the center of the combustion chamber. The multiple protruding walls 530 are provided at intervals along the circumferential direction. The multiple protruding walls 530 are preferably arranged at equal intervals along the circumferential direction. The number of protruding walls 530 is set to, for example, about 7 to 10. In this embodiment, the number of protruding walls 530 is set to 9.

[0021] As shown in FIGS. 3 and 4 , the protruding wall 530 has a forward facing surface 532 and an inverse facing surface 534 .

[0022] The directly opposed surface 532 faces the swirl flow SW in the flow direction of the swirl flow SW. The directly opposed surface 532 guides the flame B that has collided with the peripheral wall 520 to the center of the combustion chamber. The directly opposed surface 532 has a curved shape that is convex in the flow direction of the swirl flow SW.

[0023] The opposite facing surface 534 faces the swirl flow SW in the direction opposite to the flow direction of the swirl flow SW. The opposite facing surface 534 has a curved shape that is convex in the direction opposite to the flow direction of the swirl flow SW.

[0024] As shown in Fig. 5, the directly opposed surface 532 is configured so that the momentum of flame B1 returning to the center of the combustion chamber via the directly opposed surface 532 after colliding with the peripheral wall 520 is greater than the momentum of flame B2 returning to the center of the combustion chamber via the reverse opposed surface 534 after colliding with the peripheral wall 520. In this embodiment, the radius of curvature of the directly opposed surface 532 is greater than the radius of curvature of the reverse opposed surface 534. The radius of curvature of the directly opposed surface 532 is preferably about 1.5 to 5 times, and more preferably about 2 times, the radius of curvature of the reverse opposed surface 534. In Fig. 5, flame B1 is shown by a solid line, and flame B2 is shown by a dashed line.

[0025] In other words, the directly opposed surface 532 guides the tip of the flame B1 toward the center of the combustion chamber while suppressing a decrease in the momentum of the flame B1 that collides with the directly opposed surface 532, while the reverse opposed surface 534 reduces the momentum of the flame B2 that collides with the reverse opposed surface 534, thereby causing the tip of the flame B2 to remain in the space S (see Figure 5) between the flames B1 that are adjacent to each other in the circumferential direction of the combustion chamber and near the protruding wall 530.

[0026] As described above, in the internal combustion engine 1 of this embodiment, the flame B1 that passes through the directly opposed surface 532 after colliding with the peripheral wall 520 attempts to return to the center of the combustion chamber, while the flame B2 that passes through the reversed surface 534 after colliding with the peripheral wall 520 attempts to remain in the space of the combustion chamber near the peripheral wall 520. This prevents the flame B1 that collides with the directly opposed surface 532 of one protruding wall 530 and the flame B1 that collides with the reversed surface 534 of the one protruding wall 530 from interfering with each other, and prevents the flames from remaining near the peripheral wall 520 as a result. This promotes utilization of the air in the center of the combustion chamber, thereby improving combustion.

[0027] The shapes of the forward facing surface 532 and the reverse facing surface 534 are not limited to being curved. For example, both the forward facing surface 532 and the reverse facing surface 534 may be formed flat, or only one of them may be formed in a curved shape.

[0028] Aspects It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0029] a piston that is movable relative to the cylinder liner in a central axial direction of the cylinder liner and has a cavity formed at a position facing the cylinder head; and an injector that injects fuel from the cylinder head toward the cavity, wherein the cylinder head and the intake valve are configured to form a swirl flow in a combustion chamber formed between the cylinder head and the piston, and the injector injects the fuel radially outward from a center of the combustion chamber, and the piston is formed at a position where it collides with a flame formed by ignition of the fuel injected from the injector, and includes: a peripheral wall that has a shape that continues in the circumferential direction of the cylinder liner; and a plurality of protruding walls that are provided at intervals in the circumferential direction of the peripheral wall, each of which has a shape that protrudes from the peripheral wall toward the center of the combustion chamber, the protruding wall has a directly opposed surface that faces the swirl flow in the flow direction of the swirl flow and guides the flame that collides with the peripheral wall to a center of the combustion chamber, and a reversed surface that faces the swirl flow in the opposite direction to the flow direction of the swirl flow, and the directly opposed surface is configured so that the momentum of the flame that returns to the center of the combustion chamber via the directly opposed surface after colliding with the peripheral wall is greater than the momentum of the flame that returns to the center of the combustion chamber via the reversed surface after colliding with the peripheral wall.

[0030] In this internal combustion engine, the flame that passes through the directly opposed surface after colliding with the peripheral wall tends to return to the center of the combustion chamber, while the flame that passes through the oppositely opposed surface after colliding with the peripheral wall tends to remain in the space in the combustion chamber near the peripheral wall. This prevents the flame that hits the directly opposed surface of one protruding wall and the flame that hits the oppositely opposed surface of the one protruding wall from interfering with each other, and prevents the flame from remaining near the peripheral wall as a result. This promotes the use of air in the center of the combustion chamber, thereby improving combustion.

[0031] (Aspect 2) The internal combustion engine according to Aspect 1, wherein the directly opposed surface has a curved shape that is convex in a flow direction of the swirl flow, the reverse opposed surface has a curved shape that is convex in a direction opposite to the flow direction of the swirl flow, and a radius of curvature of the directly opposed surface is larger than a radius of curvature of the reverse opposed surface.

[0032] It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the description of the above embodiments, and further includes all modifications within the meaning and scope of the claims.

[0033] 1 internal combustion engine, 100 cylinder liner, 200 cylinder head, 300 intake valve, 400 exhaust valve, 500 piston, 502 partition wall, 504 top surface, 510 bottom wall, 520 peripheral wall, 530 protruding wall, 532 directly opposed surface, 534 oppositely opposed surface, 600 injector, B flame, CA cavity, h1 intake port, h2 exhaust port, SW swirl flow.

Claims

DEPCT681. An internal combustion engine comprising a cylinder liner with an inner circumferential surface, a cylinder head connected to the liner with intake and exhaust ports, intake valves that open and close the intake ports, exhaust valves that open and close the exhaust ports, a piston that is relatively movable in the central axis of the liner relative to the liner and a cavity molded to face the cylinder head, and an injector that injects fuel from the cylinder head into the cavity. The cylinder head and intake valve are molded to form swirling flow in the combustion chamber between the cylinder head and the piston. The injector injects fuel outward in a radial direction across the liner from the center of the combustion chamber. The piston, including its circumferential walls, is molded to meet the flame ignited by the fuel injected from the injector and has a continuous shape along the circumferential direction of the liner, and a number of protruding walls spaced apart along the circumferential direction of the walls.A number of projecting walls, each with a shape extending from the perimeter wall toward the center of the combustion chamber, each projecting wall has a forward-facing surface that faces the vortices in the direction of vortice flow and guides the flame impacting the perimeter wall toward the center of the combustion chamber, and an opposite-facing surface that faces the vortices in the opposite direction of vortice flow. The forward-facing surfaces are configured in such a way that the momentum of the flame returning toward the center of the combustion chamber through the forward-facing surface after impact with the perimeter wall is greater than the momentum of the flame returning toward the center of the combustion chamber through the opposite-facing surface after impact with the perimeter wall.

2. Internal combustion engine according to claim 1, where the forward-facing surfaces are curved in shape to bulge in the direction of vortice flow.

3. Internal combustion engine under claim 2, where each projecting wall has a top section formed between the projecting and opposite surfaces and curves to convex towards the center of the combustion chamber.

4. Internal combustion engine under claim 3, where the angle formed by the straight line passing through the concavity transition between the projecting and top section and the straight line passing through the concavity transition between the opposite surface and top section is an acute angle.

5. Internal combustion engine under claim 1, where the piston has an inclined surface facing the cylinder head and inclined to gradually approach the cylinder head outwards in the radial direction; the inclined surface is formed on the outside of the wall along the circumference in the radial direction and continues as an annular shape in the circumferential direction, and the projecting wall is at a certain distance from the inclined surface;

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