internal combustion engine

Abstract

To provide an internal combustion engine which can increase a temperature of an oil early.SOLUTION: An internal combustion engine includes: an outer wall of a cylinder having a side surface facing to the outside and provided with an opening included in a passage in which an oil passes and recessed from the side surface; and a cover which closes the opening. The passage includes a labyrinth part which is provided with ribs each protruding from at least one of the outer wall of the cylinder and the cover to the inside of the opening to be arranged along the outer wall of the cylinder and extending in a direction intersecting with a vertical direction and which enables the oil to flow along the ribs.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] A conventional internal combustion engine is equipped with an oil drop passage that guides oil from the upper cylinder head to an oil sump, and a sub-oil return passage that guides oil from the oil sump to the lower crankcase. The oil sump is positioned in the oil path within the cylinder block so that heat exchange can occur between the oil in the oil sump and the outer wall of the cylinder bore. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-247218 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional internal combustion engines, oil receives heat in the oil sump, but the contact area between the oil flowing through the oil sump and the outer wall of the cylinder bore is small, so the oil temperature does not easily rise.

[0005] An object of the present invention is to provide an internal combustion engine that is capable of quickly increasing the oil temperature. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the internal combustion engine of the present invention comprises an outer wall of a cylinder having a side facing outward, which is included in a passage through which oil flows and which is provided with an opening recessed from the side, and a cover which closes the opening, and the passage includes a labyrinth portion which protrudes from at least one of the outer wall of the cylinder and the cover into the opening and is provided with ribs which extend along the outer wall of the cylinder and in a direction intersecting the vertical direction, allowing the oil to flow along the ribs.

[0007] With this configuration, the oil flows gradually downward along the ribs in a direction intersecting the vertical direction. This means that the distance the oil flows through the passage is longer than when the oil flows vertically downward at the opening. This increases the time the oil spends flowing through the passage, allowing the oil to absorb heat from the cylinder's outer wall for a longer period of time. This promotes heat exchange between the cylinder's outer wall and the oil, allowing the oil temperature to rise more quickly.

[0008] In the internal combustion engine according to the present invention, the passage includes a plurality of oil outlets that open into the opening and are connected to different flow paths.

[0009] According to this configuration, oil can be discharged from multiple oil outlets at the opening provided with the labyrinth portion. Therefore, oil that passes through the opening is supplied to different flow paths from the multiple oil outlets. This allows the internal combustion engine to distribute oil in different directions without providing a dedicated passage. Therefore, the internal combustion engine can reduce the number of machining steps required to provide a dedicated passage, thereby reducing costs.

[0010] In the internal combustion engine according to the present invention, two of the plurality of oil outlets open into the opening at both ends of the labyrinth portion in the lateral direction along the outer wall of the cylinder.

[0011] With this configuration, when oil flows through the passage, it flows along the ribs provided in the labyrinth portion. Two of the multiple oil outlets open into the opening at both ends of the labyrinth portion in the horizontal direction along the outer wall of the cylinder, so that the oil flows toward the two oil outlets while splitting horizontally. This allows the internal combustion engine to distribute the oil in two opposite directions in the horizontal direction without providing a dedicated passage. Therefore, the internal combustion engine can reduce the number of machining steps required to provide a dedicated passage, further reducing costs.

[0012] In the internal combustion engine according to the present invention, the plurality of oil outlets open into the opening at different positions in the up-down direction, and at least one of the plurality of oil outlets is provided on the upper surface of the rib.

[0013] According to this configuration, when oil flows through the passage, it flows along the upper surface of the rib toward the oil outlet provided on the upper surface of the rib. In other words, the oil initially flows toward the oil outlet located higher among the multiple oil outlets. Then, the oil that does not fit into that oil outlet overflows and flows toward the oil outlet located lower. In this way, by providing one oil outlet at a higher position than the other oil outlet, the amount of oil flowing into one oil outlet can be made greater than the other oil outlet. This allows the internal combustion engine to adjust the amount of oil flowing into the multiple oil outlets.

[0014] Furthermore, with this configuration, the internal combustion engine can adjust the amount of oil without providing a dedicated passage by providing at least one of the multiple oil outlets on the upper surface of the rib, which reduces the number of machining steps required to provide a dedicated passage, further reducing costs.

[0015] In addition, in the internal combustion engine of the present invention, the rib has a first rib that protrudes from the outer wall of the cylinder toward the cover and is spaced apart from the cover, and a second rib that protrudes from the cover toward the outer wall of the cylinder and is spaced apart from the outer wall of the cylinder, and the upper surface of the first rib extends obliquely downward toward the cover, and the upper surface of the second rib extends obliquely downward toward the outer wall of the cylinder.

[0016] With this configuration, when the internal combustion engine is stopped and the oil flow stops, the oil flows downward through the gap between the first rib and the cover and the gap between the second rib and the outer wall of the cylinder, thereby preventing the oil from stagnating in the labyrinth portion.

[0017] Furthermore, with this configuration, the oil that flows down the gap between the second rib and the outer wall of the cylinder flows down along the outer wall of the cylinder. Because the oil flows down along the outer wall of the cylinder, it can absorb heat from the outer wall of the cylinder. This allows the internal combustion engine to increase the oil temperature more quickly. [Effects of the Invention]

[0018] According to the present invention, the oil temperature can be increased quickly. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a cross-sectional view showing a partial configuration of an internal combustion engine according to this embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing the internal combustion engine of this embodiment taken along line F2-F2 in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] (Embodiment) The internal combustion engine 1 according to this embodiment will be described below with reference to the drawings. The configuration of the embodiment described below, as well as the actions and results (effects) brought about by this configuration, are merely examples and are not limited to the following description. Note that in this specification, ordinal numbers are used only to distinguish between parts and members, and do not indicate order or priority.

[0021] Fig. 1 is a cross-sectional view showing a partial configuration of an internal combustion engine 1 according to this embodiment, and Fig. 2 is a cross-sectional view showing the internal combustion engine 1 of this embodiment along line F2-F2 in Fig. 1. Note that the internal combustion engine 1 of this embodiment is a reciprocating engine, but is not limited to this. Furthermore, the number of cylinders of the internal combustion engine 1 is not limited.

[0022] As shown in Fig. 2, the internal combustion engine 1 includes a cylinder block 2 and a cover 3. The cylinder block 2 may be divided into, for example, a cylinder block and a cylinder head located above the cylinder block. The upper surface of the cylinder block 2 is covered by a head cover or the like.

[0023] As shown in Fig. 1, a cylinder bore 22 is provided in the cylinder block 2. The cylinder bore 22 is a cylindrical space provided in the cylinder block 2. The cylinder bore 22 also forms a combustion chamber. The cylinder bore 22 is an example of a cylinder.

[0024] The cylinder block 2 has an outer wall 22a of the cylinder bore 22. The outer wall 22a is a part of the cylinder block 2 that defines the inner circumferential surface of the cylinder bore 22. In other words, the outer wall 22a is a part of the cylinder block 2 that surrounds the cylinder bore 22.

[0025] The cover 3 closes an opening 52, which will be described later, thereby including the opening 52 and forming an oil dropping passage 5 through which oil flows.

[0026] The internal combustion engine 1 is also provided with an oil dropping passage 5. The oil dropping passage 5 is an example of a passage.

[0027] The oil dropping passage 5 is a passage for guiding oil that has lubricated the inside of the cylinder block 2, for example, to the bottom of the internal combustion engine 1. The oil dropping passage 5 is provided in a position that does not interfere with bolt holes, etc. The oil dropping passage 5 has a hole portion 51, an opening portion 52, a labyrinth portion 53, and two oil outlets 54.

[0028] Hole 51 is a space that extends substantially vertically downward from a space in which, for example, a cam is disposed. Note that in this embodiment, hole 51 is provided along outer wall 22a of cylinder bore 22 and substantially in the center between cylinder bores 22 in the lateral direction (left-right direction in FIG. 1 ) that is perpendicular to the up-down direction, but the position of hole 51 is not limited thereto. Also, in this embodiment, hole 51 is a space that extends substantially vertically downward, but hole 51 may be, for example, inclined or curved as long as it has a shape that allows oil to be guided downward by gravity.

[0029] The opening 52 is provided in the outer wall 22a of the cylinder bore 22. For example, as shown in FIG. 2, the outer wall 22a has a substantially flat side surface 22a1 facing outward. The opening 52 is included in the oil dropping passage 5 through which oil flows. The opening 52 is a hole recessed from the side surface 22a1 toward the cylinder bore 22 and open to the outside.

[0030] The outer wall 22a has a bottom surface 22a2 of the opening 52. The bottom surface 22a2 is a substantially cylindrical curved surface that follows the cylinder bore 22. The opening 52 is formed by a peripheral wall 22a3 that protrudes from the bottom surface 22a2. An end surface of the peripheral wall 22a3 is a side surface 22a1.

[0031] Opening 52 is a space for temporarily storing oil flowing from hole 51. For example, hole 51 communicates with upper end 52a of opening 52. Hole 51 may also communicate with another portion located above lower end 52b of opening 52.

[0032] Opening 52 is covered (blocked) by cover 3, and functions as a passage for guiding oil downward in internal combustion engine 1. At this time, the space between side surface 22a1 and cover 3 around opening 52 is sealed by, for example, a sealing member, and oil is prevented from leaking from opening 52.

[0033] The labyrinth portion 53 is provided in the opening 52. In this embodiment, the labyrinth portion 53 is included in the opening 52. The labyrinth portion 53 is provided with a plurality of ribs 531. The labyrinth portion 53 can also be called, for example, a serpentine portion.

[0034] The plurality of ribs 531 include a first rib 531a and a second rib 531b. The number of ribs 531 may be changed as appropriate.

[0035] The first rib 531a protrudes from the outer wall 22a of the cylinder bore 22 into the opening 52. In this embodiment, the first rib 531a protrudes from the bottom surface 22a2 of the opening 52 toward the cover 3. The first rib 531a is spaced apart from the cover 3. That is, a gap is provided between the first rib 531a and the cover 3.

[0036] A portion of the first rib 531a is disposed below the outlet of the hole 51. The first rib 531a extends along the outer wall 22a of the cylinder bore 22 and in a direction intersecting the up-and-down direction of the internal combustion engine 1, allowing oil to flow along the first rib 531a. In this embodiment, the first rib 531a is inclined obliquely downward toward one end 531a1 of the first rib 531a.

[0037] An end 531a1 of the first rib 531a is located at one end of the labyrinth portion 53 in the lateral direction. The end 531a1 of the first rib 531a is connected to the peripheral wall 22a3. Note that the end 531a1 may be spaced apart from the peripheral wall 22a3.

[0038] The first rib 531a has an oil contact surface 531a2 that comes into contact with the oil that flows from the outlet of the hole 51. The oil contact surface 531a2 is the upper surface of the first rib 531a and faces substantially upward. The oil contact surface 531a2 faces the outlet of the hole 51.

[0039] 2, when the opening 52 is closed by the cover 3, the oil contact surface 531a2 of the first rib 531a extends obliquely downward toward the cover 3. For example, the first rib 531a protrudes from the outer wall 22a of the cylinder bore 22 so as to taper toward the cover 3.

[0040] The second rib 531b protrudes from the cover 3 into the opening 52. In the present embodiment, the second rib 531b protrudes from the cover 3 toward the bottom surface 22a2 of the opening 52. The second rib 531b is spaced apart from the outer wall 22a. That is, a gap is provided between the second rib 531b and the outer wall 22a.

[0041] The second rib 531b is spaced downward from the first rib 531a. The second rib 531b is located between the first rib 531a and the lower end 52b of the opening 52. A portion of the first rib 531a and a portion of the second rib 531b overlap in the vertical direction.

[0042] The second rib 531b extends along the outer wall 22a of the cylinder bore 22 and in a direction intersecting the vertical direction of the internal combustion engine 1. In this embodiment, the second rib 531b extends substantially parallel to the first rib 531a. Note that the extending direction of the first rib 531a and the extending direction of the second rib 531b may be different from each other.

[0043] The second rib 531b has an oil contact surface 531b1 that comes into contact with the oil flowing from the first rib 531a. The oil contact surface 531b1 is the upper surface of the second rib 531b and faces substantially upward. The oil contact surface 531b1 faces the first rib 531a.

[0044] When the opening 52 is closed by the cover 3, the oil contact surface 531b1 of the second rib 531b extends obliquely downward toward the bottom surface 22a2 of the outer wall 22a of the cylinder bore 22. For example, the second rib 531b protrudes from the cover 3 so as to taper toward the bottom surface 22a2 of the outer wall 22a.

[0045] The oil outlet 54 includes a first oil outlet 541 and a second oil outlet 542. The multiple oil outlets 54 open into the interior of the opening 52 at both ends of the labyrinth portion 53 in the lateral direction and are connected to different flow paths 55 from each other.

[0046] The first oil outlet 541 is provided on the oil contact surface 531a2 of the first rib 531a near the end 531a1 of the first rib 531a. That is, the first oil outlet 541 opens into the opening 52 at one end of the labyrinth portion 53 in the lateral direction. The first oil outlet 541 may be provided at another position on the oil contact surface 531a2.

[0047] The second oil outlet 542 is provided below the first oil outlet 541. That is, the first oil outlet 541 and the second oil outlet 542 open into the opening 52 at positions different from each other in the up-down direction. The second oil outlet 542 opens into the peripheral wall 22a3 at the other end of the labyrinth portion 53 in the lateral direction.

[0048] The flow path 55 includes a first flow path 551 and a second flow path 552. The first flow path 551 is connected to the first oil outlet 541, extends downward, and is connected to, for example, the vicinity of the rear ball bearing 6 that supports the balance shaft. The outlet of the first flow path 551 is located above at least a portion of the rear ball bearing 6. Therefore, the first flow path 551 can supply oil to the rear ball bearing 6.

[0049] The second flow passage 552 is connected to the second oil outlet 542, extends in a substantially horizontal direction, and is connected to, for example, the vicinity of the front ball bearing 7 that supports the balance shaft. The outlet of the second flow passage 552 is located above at least a portion of the front ball bearing 7. Therefore, the second flow passage 552 can supply oil to the front ball bearing 7.

[0050] In this embodiment, the diameter of the first oil outlet 541 is smaller than the diameter of the second oil outlet 542. In other words, the cross-sectional area of ​​the first oil outlet 541 is smaller than the cross-sectional area of ​​the second oil outlet 542. However, the diameter of the oil outlet 54 may be changed as appropriate in accordance with the amount of oil flowing through the oil dropping passage 5.

[0051] In the internal combustion engine 1 described above, for example, oil that has lubricated the inside of the cylinder block 2 flows vertically downward through the hole 51 of the oil dropping passage 5. The oil that has flowed from the hole 51 flows into the labyrinth portion 53 of the opening 52.

[0052] The oil that flows from the outlet of hole 51 into opening 52 flows along oil contact surface 531a2 of first rib 531a provided below hole 51 toward first oil outlet 541 provided on oil contact surface 531a2. At this time, the oil comes into contact with outer wall 22a of cylinder bore 22, and receives heat from outer wall 22a, causing the oil to increase in temperature. A portion of the oil, whose viscosity has decreased due to the increase in temperature, passes from first oil outlet 541 through first flow path 551 and is supplied to rear ball bearing 6.

[0053] On the other hand, the oil that continues to flow from the hole 51 eventually overflows from the first oil outlet 541. As a result, another part of the oil flows to the second rib 531b provided below the first rib 531a.

[0054] At this time, since the first rib 531a protrudes from the outer wall 22a of the cylinder bore 22 and the oil contact surface 531a2 is inclined obliquely downward toward the cover 3, some of the oil flows down into the gap between the first rib 531a and the cover 3. The oil may also flow downward, over the upper end of the first rib 531a.

[0055] The oil flowing from first rib 531a flows along oil contact surface 531b1 of second rib 531b toward second oil outlet 542, which is located below first oil outlet 541. At this time, the oil comes into contact with outer wall 22a of cylinder bore 22, and is heated by outer wall 22a. The oil, whose viscosity has decreased due to the temperature increase, is supplied from second oil outlet 542 through second flow path 552 to front ball bearing 7.

[0056] At this time, the second rib 531b protrudes from the cover 3, and the oil contact surface 531b1 is inclined obliquely downward toward the outer wall 22a of the cylinder bore 22, so that part of the oil flows down into the gap between the second rib 531b and the bottom surface 22a2 of the outer wall 22a of the cylinder bore 22. As a result, the oil flows down along the bottom surface 22a2 of the outer wall 22a and flows to the second oil outlet 542 while receiving heat from the outer wall 22a.

[0057] When the internal combustion engine 1 is stopped, oil is discharged from the first oil outlet 541 to the outside of the opening 52, and is also discharged from the second oil outlet 542 through the gap between the first rib 531a and the cover 3 and the gap between the second rib 531b and the outer wall 22a of the cylinder bore 22. Therefore, the labyrinth portion 53 can prevent oil from remaining in the opening 52.

[0058] As described above, the internal combustion engine 1 of this embodiment includes the outer wall 22a of the cylinder bore 22 and the cover 3. The outer wall 22a of the cylinder bore 22 has a side surface 22a1 facing outward, is included in the oil dropping passage 5 through which oil flows, and is provided with an opening 52 recessed from the side surface 22a1. The cover 3 closes the opening 52. The oil dropping passage 5 includes a labyrinth portion 53. The labyrinth portion 53 is provided with ribs 531 that protrude into the opening 52 from at least one of the outer wall 22a of the cylinder bore 22 and the cover 3, extend along the outer wall 22a of the cylinder bore 22, and extend in a direction intersecting the up-down direction, allowing the oil to flow along the ribs 531.

[0059] As a result, the oil gradually flows downward while flowing along the ribs 531 in a direction intersecting the up-down direction. That is, the distance that the oil flows in the oil dropping passage 5 is longer than when the oil flows vertically downward in the opening 52.

[0060] This increases the time that the oil flows through the oil dropping passage 5, allowing the oil to receive heat from the outer wall 22a of the cylinder bore 22 for a longer period of time in the oil dropping passage 5. This promotes heat exchange between the outer wall 22a of the cylinder bore 22 and the oil, allowing the oil temperature to rise quickly.

[0061] In this embodiment, the oil dropping passage 5 opens into the opening 52 and includes a plurality of oil outlets 54 connected to different flow paths 55 .

[0062] For example, in the opening 52 provided with the labyrinth portion 53, oil can be discharged from a plurality of oil outlets 54. Therefore, the oil that has passed through the opening 52 is supplied to different flow paths 55 from the plurality of oil outlets 54.

[0063] This allows the internal combustion engine 1 to distribute oil in different directions without providing a dedicated passage, thereby reducing the number of machining steps required to provide a dedicated passage, and thus reducing costs.

[0064] In this embodiment, the first oil outlet 541 and the second oil outlet 542 open into the opening 52 at both ends of the labyrinth portion 53 in the lateral direction along the outer wall 22 a of the cylinder bore 22 .

[0065] For example, when oil flows through the oil dropping passage 5, it flows along the ribs 531 provided in the labyrinth portion 53. The first oil outlet 541 and the second oil outlet 542 open into the opening 52 at both ends of the labyrinth portion 53 in the lateral direction along the outer wall 22a of the cylinder bore 22, so that the oil flows toward the first oil outlet 541 and the second oil outlet 542 while splitting in the lateral direction along the outer wall 22a of the cylinder bore 22.

[0066] This allows the internal combustion engine 1 to distribute oil in two opposite lateral directions without providing a dedicated passage, thereby reducing the number of machining steps required to provide a dedicated passage, and further reducing costs.

[0067] In addition, in this embodiment, the multiple oil outlets 54 open into the interior of the opening 52 at different positions in the vertical direction, and the first oil outlet 541 of the multiple oil outlets 54 is provided on the oil contact surface 531a2 of the first rib 531a.

[0068] For example, when oil flows through the oil drop passage 5, the oil flows along the oil contact surface 531a2 of the first rib 531a toward the first oil outlet 541 provided on the oil contact surface 531a2 of the first rib 531a. In other words, the oil first flows toward the oil outlet 54 (first oil outlet 541) located at the upper end of the multiple oil outlets 54. Then, the oil that does not fit into the oil outlet 54 overflows and flows toward the oil outlet 54 (second oil outlet 542) located at the lower end. In this way, by providing one oil outlet 54 at a higher position than the other oil outlet 54, the amount of oil flowing into one oil outlet 54 can be made greater than the other oil outlet 54. This allows the internal combustion engine 1 to adjust the amount of oil flowing into the multiple oil outlets 54.

[0069] Furthermore, the internal combustion engine 1 can adjust the amount of oil without providing a dedicated passage by providing the first oil outlet 541, among the multiple oil outlets 54, on the oil contact surface 531a2 of the first rib 531a. This allows the internal combustion engine 1 to reduce the number of machining steps required to provide a dedicated passage, further reducing costs.

[0070] In this embodiment, the rib 531 has a first rib 531a and a second rib 531b. The first rib 531a protrudes from the outer wall 22a of the cylinder bore 22 toward the cover 3 and is spaced apart from the cover 3. The second rib 531b protrudes from the cover 3 toward the outer wall 22a of the cylinder bore 22 and is spaced apart from the outer wall 22a of the cylinder bore 22. An oil contact surface 531a2 of the first rib 531a extends obliquely downward toward the cover 3, and an oil contact surface 531b1 of the second rib 531b extends obliquely downward toward the outer wall 22a of the cylinder bore 22.

[0071] For example, when oil flows through the oil dropping passage 5, the oil flows over the oil contact surface 531a2 of the first rib 531a and the oil contact surface 531b1 of the second rib 531b. Because the oil contact surface 531a2 extends obliquely downward toward the cover 3, the oil flowing over the oil contact surface 531a2 of the first rib 531a flows toward the cover 3 and drops into the gap between the first rib 531a and the cover 3. Because the oil contact surface 531b1 extends obliquely downward toward the outer wall 22a of the cylinder bore 22, the oil flowing over the oil contact surface 531b1 of the second rib 531b flows toward the outer wall 22a of the cylinder bore 22 and drops into the gap between the second rib 531b and the outer wall 22a of the cylinder bore 22.

[0072] When the flow of oil stops due to the internal combustion engine 1 being stopped, the oil flows downward through the gap between the first rib 531a and the cover 3 and the gap between the second rib 531b and the outer wall 22a of the cylinder bore 22. This prevents the oil from stagnating in the labyrinth portion 53 in the internal combustion engine 1.

[0073] Furthermore, the oil that flows down through the gap between the second rib 531b and the outer wall 22a of the cylinder bore 22 flows down along the outer wall 22a of the cylinder bore 22. Because the oil flows down along the outer wall 22a of the cylinder bore 22, it can receive heat from the outer wall 22a of the cylinder bore 22. This makes it possible to raise the temperature of the oil even more quickly.

[0074] Although the embodiments of the present invention have been described above, the above embodiments are merely examples and are not intended to limit the scope of the invention. The above embodiments can be implemented in various other forms, and various omissions, substitutions, combinations, and modifications can be made without departing from the spirit of the invention. Furthermore, the specifications of each configuration, shape, and the like (structure, type, direction, format, size, length, width, thickness, height, number, arrangement, position, material, etc.) can be modified as appropriate. [Explanation of symbols]

[0075] 1. Internal combustion engine 22 Cylinder bore (cylinder) 22a Exterior wall 22a1 side 3 Cover 5 Oil removal passage (passage) 52 Opening 53 Labyrinth Club 531 Rib 531a First Rib 531a2 Oil contact surface (upper surface) 531b Second Rib 531b1 Oil contact surface (upper surface) 54 Oil outlet 55 Flow path

Claims

1. an outer wall of the cylinder having an outwardly facing side, the outer wall including an oil passage and having an opening recessed from the side; a cover that closes the opening; Equipped with The passage includes a labyrinth portion having ribs that protrude into the opening from at least one of the outer wall of the cylinder and the cover and extend along the outer wall of the cylinder in a direction intersecting the up-down direction, allowing the oil to flow along the ribs, and a plurality of oil outlets that open into the opening and are connected to different flow paths. Internal combustion engine.

2. Two of the plurality of oil outlets open into the opening at both ends of the labyrinth portion in the lateral direction along the outer wall of the cylinder.

2. The internal combustion engine according to claim 1.

3. The plurality of oil outlets open into the opening at positions different from each other in the vertical direction, At least one of the plurality of oil outlets is provided on the upper surface of the rib.

3. An internal combustion engine according to claim 1 or 2.

4. The rib has a first rib that protrudes from the outer wall of the cylinder toward the cover and is spaced apart from the cover, and a second rib that protrudes from the cover toward the outer wall of the cylinder and is spaced apart from the outer wall of the cylinder, an upper surface of the first rib extends obliquely downward toward the cover; The upper surface of the second rib extends obliquely downward toward the outer wall of the cylinder. An internal combustion engine according to any one of claims 1 to 3.

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