Internal combustion engine
Patent Information
- Application Number
- JP2022076997
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2022-05-09
- Publication Date
- 2025-05-12
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to an internal combustion engine.
Background Art
[0002] For example, Japanese Patent Translation 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 upwardly open outer bowl portion and protrusions evenly arranged on the circumference of the outer bowl portion.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In the internal combustion engine described in Japanese Patent Translation Publication No. 2011-502226, flames colliding with each of the portions adjacent to each other in the circumferential direction across the protrusions in the outer bowl portion tend to move toward the central portion in the combustion chamber due to the protrusions. At this time, the flames adjacent to each other across the protrusions may interfere with each other, and the flames may stay near the outer bowl portion. In this case, the utilization of air in the central portion of the combustion chamber is not promoted, so the combustion efficiency decreases.
[0005] An object of the present invention is to provide an internal combustion engine capable of improving combustion in a combustion chamber.
Means for Solving the Problems
[0006] An internal combustion engine according to one aspect of this invention comprises a cylinder liner having a cylindrical inner surface, a cylinder head connected to the cylinder liner and having an intake port and an exhaust port, an intake valve for opening and closing the intake port, an exhaust valve for opening and closing the exhaust port, a piston that is movable relative to the cylinder liner in the direction of the central axis of the cylinder liner and has a cavity formed at a position opposite to the cylinder head, and an injector for injecting fuel from the cylinder head toward the cavity, wherein the cylinder head and the intake valve are configured to form a swirl flow in the combustion chamber formed between the cylinder head and the piston, the injector injects the fuel from the center of the combustion chamber toward the radially outward direction of the cylinder liner, and the piston is moved toward the cavity from the injector The cylinder liner includes a peripheral wall formed at a position where it collides with the flame formed when the injected fuel ignites, and having a shape that connects to 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 central part of the combustion chamber, wherein the protruding walls have a forward-facing surface that faces the swirl flow in the direction of the swirl flow and guides the flame that collides with the peripheral wall toward the central part of the combustion chamber, and a reverse-facing surface that faces the swirl flow in the opposite direction to the direction of the swirl flow, and the forward-facing surface is configured such that the momentum of the flame returning to the central part of the combustion chamber via the forward-facing surface after collision with the peripheral wall is greater than the momentum of the flame returning to the central part of the combustion chamber via the reverse-facing surface after collision with the peripheral wall. [Effects of the Invention]
[0007] This invention provides an internal combustion engine capable of improving combustion in the combustion chamber. [Brief explanation of the drawing]
[0008] [Figure 1] This is a schematic plan view showing an internal combustion engine in one embodiment of the present invention. [Figure 2]This is a cross-sectional view taken along line II-II in Figure 1. [Figure 3] This is a perspective view of the piston cavity. [Figure 4] This is a schematic plan view of the cavity. [Figure 5] This is a magnified view of the vicinity of the protruding wall. [Modes for carrying out the invention]
[0009] Embodiments of this invention will be described with reference to the drawings. In the drawings referred to below, the same or equivalent components are given the same numbers.
[0010] Figure 1 is a schematic plan view of an internal combustion engine in one embodiment of the present invention. Figure 2 is a cross-sectional view taken along line II-II in Figure 1. As shown in Figures 1 and 2, the internal combustion engine 1 comprises a cylinder liner 100, a cylinder head 200, an intake valve 300, an exhaust valve 400, a piston 500, and an injector 600. Although only one cylinder is shown in Figures 1 and 2, the internal combustion engine 1 is also applicable to multi-cylinder types.
[0011] The cylinder liner 100 is formed in a cylindrical shape.
[0012] The cylinder head 200 is connected to the end of the cylinder liner 100. The cylinder head 200 is formed in a disc shape. The cylinder head 200 has an intake port h1 and an exhaust port h2.
[0013] The intake valve 300 opens and closes the intake port h1. The intake valve 300 is held in place by the cylinder head 200.
[0014] The exhaust valve 400 opens and closes the exhaust port h2. The exhaust valve 400 is held in place by the cylinder head 200.
[0015] The piston 500 is movable relative to the cylinder liner 100 along the central axis direction of the cylinder liner 100 (the vertical direction in FIG. 2). As shown in FIG. 2, the piston 500 has a cavity CA formed at a position facing the cylinder head 200. The cavity CA has a shape that depresses in a direction away from the cylinder head 200 from the top surface 504 of the piston 500 (the downward direction in FIG. 2). A combustion chamber is formed between the piston 500 including this cavity CA and the cylinder head 200. The piston 500 has a partition wall 502 that partitions the cavity CA.
[0016] The cylinder head 200 and the intake valve 300 are configured to form a swirl flow SW (see FIG. 3) in the combustion chamber.
[0017] The injector 600 is provided at a position of the cylinder head 200 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 outward in the radial direction of the cylinder liner 100 from the central portion in the combustion chamber.
[0018] Here, referring also to FIGS. 3 and 4, the partition wall 502 of the piston 500 will be described in detail. FIG. 3 is a perspective view of the cavity of the piston. FIG. 4 is a plan view schematically showing the cavity. As shown in FIGS. 2 to 4, the partition wall 502 has a bottom wall 510, a peripheral wall 520, and a plurality of protruding walls 530.
[0019] 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 so as to gradually separate from the cylinder head 200 toward the outside in the radial direction from the central portion facing the injector 600 in the central axis direction.
[0020] The peripheral wall 520 has a shape that stands up from the edge of the bottom wall 510. The peripheral wall 520 has a shape that is annularly connected in the circumferential direction of the cylinder liner 100. The peripheral wall 520 is formed at a position where it collides with the flame B formed by the ignition of the fuel injected from the injector 600. As shown in FIGS. 2 and 3, the peripheral wall 520 has a shape that curves so as to be convex outward in the radial direction.
[0021] Each protruding wall 530 has a shape that protrudes from the peripheral wall 520 toward the central portion in the combustion chamber. The plurality of protruding walls 530 are provided at intervals along the circumferential direction. It is preferable that the plurality of protruding walls 5 three0 are arranged so as to be equally spaced along the circumferential direction. The number of the protruding walls 530 is set to about 7 to 10, for example. In the present embodiment, the number of the protruding walls 530 is set to 9.
[0022] As shown in FIGS. 3 and 4, the protruding wall 530 has a facing surface 532 and a reverse facing surface 534.
[0023] The facing surface 532 faces the swirl flow SW in the flow direction of the swirl flow SW. The facing surface 532 guides the flame B that has collided with the peripheral wall 520 to the central portion in the combustion chamber. The facing surface 532 has a shape that curves so as to be convex in the flow direction of the swirl flow SW.
[0024] The reverse facing surface 534 faces the swirl flow SW in the direction opposite to the flow direction of the swirl flow SW. The reverse facing surface 534 has a shape that curves so as to be convex in the direction opposite to the flow direction of the swirl flow SW.
[0025] As shown in Figure 5, the forward-facing surface 532 is configured such that the momentum of flame B1 returning to the center of the combustion chamber via the forward-facing surface 532 after impacting the peripheral wall 520 is greater than the momentum of flame B2 returning to the center of the combustion chamber via the reverse-facing surface 534 after impacting the peripheral wall 520. In this embodiment, the radius of curvature of the forward-facing surface 532 is formed to be larger than the radius of curvature of the reverse-facing surface 534. The radius of curvature of the forward-facing surface 532 is preferably about 1.5 to 5 times, and more preferably about 2 times, the radius of curvature of the reverse-facing surface 534. In Figure 5, flame B1 is shown by a solid line and flame B2 is shown by a dashed line.
[0026] In other words, the forward-facing surface 532 suppresses the decrease in momentum of the flame B1 that collides with the forward-facing surface 532 and guides the tip of the flame B1 toward the center of the combustion chamber, while the reverse-facing surface 534 reduces the momentum of the flame B2 that collides with the reverse-facing surface 534, thereby causing the tip of the flame B2 to remain in the space S (see Figure 5) in the combustion chamber between flames B1 that are adjacent to each other in the circumferential direction and in the vicinity of the protruding wall 530.
[0027] As described above, in the internal combustion engine 1 of this embodiment, the flame B1 that passes through the directly opposite surface 532 after impacting the peripheral wall 520 tends to return to the central part of the combustion chamber, while the flame B2 that passes through the inversely opposite surface 534 after impacting the peripheral wall 520 tends to remain in the space near the peripheral wall 520 within the combustion chamber. Therefore, interference between the flame B1 that impacts the directly opposite surface 532 of one protruding wall 530 and the flame B1 that impacts the inversely opposite surface 534 of the same protruding wall 530, and the resulting stagnation of the flame near the peripheral wall 520, is suppressed. As a result, the utilization of air in the central part of the combustion chamber is promoted, and combustion is improved.
[0028] Furthermore, the forward opposing surface 532 and the reverse opposing surface 534 are not limited to curved shapes. For example, both the forward opposing surface 532 and the reverse opposing surface 534 may be formed flat, or only one of them may be formed in a curved shape.
[0029] [Pattern] Those skilled in the art will understand that the exemplary embodiments described above are specific examples of the following embodiments.
[0030] (Aspect 1) A cylinder liner having a cylindrical inner surface, A cylinder head connected to the cylinder liner and having an intake port and an exhaust port, An intake valve that opens and closes the aforementioned intake port, An exhaust valve that opens and closes the exhaust port, A piston having a cavity formed at a position opposite to the cylinder head, which is movable relative to the cylinder liner in the direction of the central axis of the cylinder liner, The system includes an injector that injects fuel from the cylinder head toward the cavity, The cylinder head and the intake valve are configured to form a swirl flow in the combustion chamber formed between the cylinder head and the piston. The injector injects the fuel from the central part of the combustion chamber outward in the radial direction of the cylinder liner, The aforementioned piston is A circumferential wall is formed at a position where it collides with the flame formed when the fuel injected from the injector ignites, and has a shape that connects to the circumferential direction of the cylinder liner, It includes a plurality of protruding walls provided at intervals in the circumferential direction of the circumferential wall, each having a shape that protrudes from the circumferential wall toward the central part of the combustion chamber, The aforementioned protruding wall is A directly opposite surface that faces the swirl flow in the direction of the swirl flow and guides the flame that has struck the peripheral wall to the central part of the combustion chamber, It has an inversely opposing surface that faces the swirl flow in the opposite direction to the flow direction of the swirl flow, An internal combustion engine in which the forward-facing surfaces are configured such that the momentum of the flame returning to the center of the combustion chamber via the forward-facing surfaces after impacting the peripheral wall is greater than the momentum of the flame returning to the center of the combustion chamber via the opposite-facing surfaces after impacting the peripheral wall.
[0031] In this internal combustion engine, flames that pass through the directly opposite surface after impacting the peripheral wall tend to return to the center of the combustion chamber, while flames that pass through the opposite surface after impacting the peripheral wall tend to remain in the space near the peripheral wall within the combustion chamber. Therefore, interference between flames that impact the directly opposite surface of one protruding wall and flames that impact the opposite surface of the same protruding wall, and the resulting flame stagnation near the peripheral wall, is suppressed. As a result, the utilization of air in the center of the combustion chamber is promoted, and combustion is improved.
[0032] (Aspect 2) The aforementioned directly opposing surfaces have a shape that is curved so as to be convex in the direction of the swirl flow, The opposite opposing surfaces have a shape that curves so as to be convex in the direction opposite to the flow direction of the swirl flow, The internal combustion engine according to embodiment 1, wherein the radius of curvature of the forward-facing surface is greater than the radius of curvature of the reverse-facing surface.
[0033] It should be noted that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the description of the embodiments above, and further includes all modifications within the meaning and scope equivalent to the claims. [Explanation of Symbols]
[0034] 1 Internal combustion engine, 100 Cylinder liner, 200 Cylinder head, 300 Intake valve, 400 Exhaust valve, 500 Piston, 502 Compartment wall, 504 Top surface, 510 Bottom wall, 520 Peripheral wall, 530 Projecting wall, 532 Opposite surfaces, 534 Opposite surfaces, 600 Injector, B Flame, CA Cavity, h1 Intake port, h2 Exhaust port, SW Swirl flow.
Claims
1. A cylinder liner having a cylindrical inner peripheral surface; a cylinder head connected to the cylinder liner and having an intake port and an exhaust port; 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 axis direction of the cylinder liner and has a cavity formed at a position facing the cylinder head; an injector that injects fuel from the cylinder head toward the cavity, 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, The injector injects the fuel from a center portion of the combustion chamber toward an outer side in a radial direction of the cylinder liner, The piston is a peripheral wall formed at a position where the flame formed by ignition of the fuel injected from the injector collides with the peripheral wall, the peripheral wall having a shape continuing in the circumferential direction of the cylinder liner; a plurality of protruding walls provided at intervals in a circumferential direction of the peripheral wall, each of the protruding walls having a shape protruding from the peripheral wall toward a center of the combustion chamber; The protruding wall is a directly opposed surface that faces the swirl flow in a flow direction of the swirl flow and guides the flame that has collided with the peripheral wall to a center portion of the combustion chamber; a counter-facing surface that faces the swirl flow in a direction opposite to the flow direction of the swirl flow, the directly opposed surface is configured so that the momentum of the flame returning 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 returning to the center of the combustion chamber via the reverse opposed surface after colliding with the peripheral wall.
2. The directly opposed surface has a curved shape that is convex in a flow direction of the swirl flow, The reverse facing surface has a shape curved so as to be convex in a direction opposite to a flow direction of the swirl flow, The internal combustion engine according to claim 1 , wherein a radius of curvature of the forward facing surface is larger than a radius of curvature of the reverse facing surface.
3. An internal combustion engine as described in claim 2, wherein the protruding wall is formed between the forward opposing surface and the reverse opposing surface and has a top that is curved convexly toward the center of the combustion chamber.
4. An internal combustion engine as described in claim 3, wherein the angle between a straight line passing through the inflection point between the forward opposing surface and the apex and a straight line passing through the inflection point between the reverse opposing surface and the apex is an acute angle.
5. The piston has an inclined surface facing the cylinder head and inclining gradually toward the cylinder head as it moves toward the outside in the radial direction, The inclined surface is formed on an outer side of the peripheral wall in the radial direction and is annularly connected in the circumferential direction, The internal combustion engine of claim 1 , wherein the protruding wall is spaced from the inclined surface.