AU2023200209A1 - Internal combustion engine - Google Patents

Abstract

OF THE DISCLOSURE In an internal combustion engine according to the present disclosure, a head cover (70) is connected to both a cylinder body portion (10) and a chain cover (60) and houses a part of a cam sprocket (22) and a part of a chain (30). The head cover (70) 5 has a flange surface (71) and a protrusion (72). The flange surface (71) contacts both the cylinder body portion (10) and the chain cover (60) to form a three-surface mating portion (T). The protrusion (72) protrudes, on an inner surface of the head cover (70) constituting a housing space that houses the cam sprocket (22) and the chain (30), along a circumferential direction of the cam sprocket (22). The protrusion (72) is located 10 closer to the housing space than the flange surface (71). 3/4 FIG.4 10(17) 30 2 77 20(21) 706 71 A 12 U71 AM T72 R3 D 818382 R4 R2 31 80

Description

3/4

FIG.4

10(17)

30 2 77 20(21)

706

71 A

12 U71 AM T72 R3

D 818382 R4 R2 31

Internal Combustion Engine

This nonprovisional application is based on Japanese Patent Application No. 2022-009972 filed on January 26, 2022 with the Japan Patent Office, the entire contents of which are hereby incorporated by reference. BACKGROUND The present disclosure relates to an internal combustion engine. Description of the Background Art Japanese Patent Laying-Open Nos. 2016-108992 and 2008-231957 are examples of documents disclosing structures of internal combustion engines. Japanese Patent Laying-Open Nos. 2016-108992 and 2008-231957 each describe an internal combustion engine having a structure intended to improve the prevention of oil leakage from a three-surface mating portion formed on a cover that houses a chain. Conventionally, in order to prevent oil flowing down an inner surface of a head cover or the like from contacting the three-surface mating portion, it has been considered to add or form a shield that guides a flow of the oil on the inner surface. However, if a separation distance between the head cover and the chain (sprocket) is increased in order to add the shield, the internal combustion engine is increased in size. SUMMARY The present disclosure has been made in view of the aforementioned problem, and an object of the present disclosure is to provide an internal combustion engine capable of preventing an increase in size while attaining improved sealing performance by preventing contact of oil with a three-surface mating portion. An internal combustion engine based on the present disclosure includes a cylinder body portion, a cam shaft, a cam sprocket, a chain, a chain cover, and a head cover. The cam shaft is provided in the cylinder body portion, and has an axial end portion protruding from a side surface of the cylinder body portion. The cam sprocket is provided on the axial end portion of the cam shaft, and causes rotation of the cam shaft. The chain is wound around the cam sprocket, and causes rotation of the cam sprocket. The chain cover is located to face the cylinder body portion in an axial direction of the cam shaft, and together with the cylinder body portion, houses a part of the cam sprocket and a part of the chain. The head cover is connected to both the cylinder body portion and the chain cover, and houses another part of the cam sprocket and another part of the chain. The head cover has a flange surface and a protrusion. The flange surface contacts both the cylinder body portion and the chain cover to form a three-surface mating portion. The protrusion protrudes, on an inner surface of the head cover constituting a housing space that houses the cam sprocket and the chain, along a circumferential direction of the cam sprocket. The protrusion is located closer to the housing space than the flange surface. According to the present disclosure, oil flowing down the inner surface of the head cover under its own weight is guided by the protrusion so as to pass over the flange surface and drop on an inner surface of the cylinder body portion or the chain cover. Thus, contact of the oil with the three-surface mating portion can be reduced. Moreover, as the protrusion protrudes along the circumferential direction of the cam sprocket, an increase in separation distance between the head cover and the sprocket can be prevented, and an increase in size of the internal combustion engine can thereby be prevented. The foregoing and other objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description of the present disclosure when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram showing a configuration of an internal combustion engine according to a first embodiment. Fig. 2 is a schematic cross-sectional view of the internal combustion engine in Fig. 1 as seen from a direction of arrows of line II-II. Fig. 3 is a perspective cross-sectional view of the internal combustion engine in Fig. 2 as seen from a direction of arrows of lineI-I. Fig. 4 is an enlarged partial cross-sectional view of a region IV in Fig. 2.

Fig. 5 is a partial cross-sectional view showing an internal combustion engine according to a second embodiment. DESCRIPTION OF THE PREFERRED EMBODIMENTS An internal combustion engine according to each embodiment of the present disclosure will be described hereinafter with reference to the drawings. In the following description of the embodiments, the same or corresponding parts in the drawings are designated by the same reference numbers and the description thereof will not be repeated. (First Embodiment) Fig. 1 is a schematic diagram showing a configuration of an internal combustion engine according to a first embodiment. Fig. 2 is a schematic cross-sectional view of the internal combustion engine in Fig. 1 as seen from a direction of arrows of line II-II. As shown in Figs. 1 and 2, an internal combustion engine 1 according to the present embodiment is specifically a V-type engine. The internal combustion engine 1 includes an engine body 2 which is substantially V-shaped when viewed in one direction. The engine body 2 has a first bank 3 protruding obliquely to an upper side U on the left side, and a second bank 4 protruding obliquely to the upper side U on the right side, when viewed in one direction. Fig. 3 is a perspective cross-sectional view of the internal combustion engine in Fig. 2 as seen from a direction of arrows of lineI-. As shown in Figs. I to 3, the internal combustion engine 1 according to the first embodiment of the present disclosure includes a cylinder body portion 10, a cam shaft 20, a cam sprocket 22, a chain 30, a chain cover 60, a head cover 70, and a rib 80. As shown in Fig. 2, the cylinder body portion 10 constitutes a part of the first bank 3 of the engine body 2 in the internal combustion engine 1. The cylinder body portion 10 has a first body flange surface 11 facing laterally (an axial direction A described later), and a second body flange surface 12 facing obliquely upward (toward the head cover 70). As shown in Figs. 1 and 2, the cylinder body portion 10 includes a cylinder block 15, a cylinder head 16, and a chain case 17. The cylinder head 16 is located on the head cover 70 side when viewed from the cylinder block 15, and pivotally supports the cam shaft 20. The cylinder head 16 is connected to the upper side U of the cylinder block 15. The chain case 17 is located on the chain cover 60 side when viewed from the cylinder block 15 and the cylinder head 16. That is, in the present embodiment, the chain case 17 has the first body flange surface 11 and the second body flange surface 12 in the cylinder body portion 10. The cylinder body portion 10 may not have the chain case 17. If the cylinder body portion 10 does not have the chain case 17, the cylinder head has the first body flange surface 11 and the second body flange surface 12. As shown in Figs. 1 and 2, the cam shaft 20 is provided in the cylinder body portion 10, and has an axial end portion 21 protruding from a side surface of the cylinder body portion 10. When viewed in the axial direction A, the camshaft 20 is located on one side in a horizontal direction of the internal combustion engine 1, with a center C in the horizontal direction as a boundary. The cam sprocket 22 is provided on the axial end portion 21 of the cam shaft 20, and causes rotation of the cam shaft 20. The internal combustion engine 1 further includes a second cam shaft 23 and a second cam sprocket 24. The second cam shaft 23 is provided in the cylinder body portion 10, and has an axial end portion 21 protruding from the side surface of the cylinder body portion 10. When viewed in the axial direction A, the second camshaft 23 is located on the same side as the (first) cam shaft 20 in the horizontal direction, with the center C as a boundary. The second cam shaft 23 is located on the center C side when viewed from the (first) cam shaft 20, and is located on the upper side U relative to the (first) cam shaft 20. Although the (first) cam shaft 20 is an intake cam shaft and the second cam shaft 23 is an exhaust cam shaft, these roles may be reversed. The second cam sprocket 24 is provided on the axial end portion of the second cam shaft 23, and causes rotation of the second cam shaft 23. The chain 30 is wound around the (first) cam sprocket 22, and causes rotation of the cam sprocket 22. The chain 30 is further wound around the second cam sprocket

24, and causes rotation of the second cam sprocket 24. The internal combustion engine 1 further includes a working shaft 40, a first working sprocket 41, a second working sprocket 42, a second chain 43, a crank sprocket 44, and a crankshaft 45. The working shaft 40 is pivotally supported to the engine body 2, and is located on the center C side when viewed from the cam shaft 20. The first working sprocket 41 is provided on an axial end portion of the working shaft 40, and is rotated clockwise when viewed from the chain cover 60 side by the working shaft 40. The chain 30 is wound around the first working sprocket 41. The first working sprocket 41 drives the chain 30 by rotating clockwise when viewed from the chain cover 60 side. As a result, a portion of the chain 30 that is opposite to the center C when viewed from the cam shaft 20 is driven from a lower side D to the upper side U. The second working sprocket 42 is provided on the axial end portion of the working shaft 40, and causes rotation of the working shaft 40 by rotating clockwise when viewed from the chain cover 60 side. The second chain 43 is a separate chain that is not connected to the (first) chain 30. The second chain 43 is wound around the second working sprocket 42. When the second chain 43 is driven, the second chain 43 causes rotation of the second working sprocket 42. The second chain 43 is wound around the crank sprocket 44. The crank sprocket 44 drives the second chain 43 by rotating clockwise when viewed from the chain cover 60 side. The crankshaft 45 is pivotally supported to the engine body 2. The crankshaft 45 is located on the center C side when viewed from the cam shaft 20, and is located on the lower side D relative to the cam shaft 20. The crank sprocket 44 is provided on an axial end portion of the crankshaft 45. Rotation of the crankshaft 45 causes rotation of the crank sprocket 44. In this manner, the chain 30 is indirectly driven by a rotational force of the crankshaft 45. The chain 30 may be directly wound around the crank sprocket 44. The internal combustion engine 1 further includes a tensioner 50. The tensioner 50 is located closer to the center C than the cam shaft 20 when viewed in the axial direction A, and more specifically is located between the cam shaft 20 and the working shaft 40 in the horizontal direction. The tensioner 50 is located on the lower side D relative to the chain 30, and applies a prescribed tension from the lower side D to the upper side U. As a result, the chain 30 has a portion extending obliquely upward from a lower end of the cam sprocket 22 toward the center C. The internal combustion engine 1 further includes an oil supply portion 55. The oil supply portion 55 is provided on the side of the cylinder body portion 10, and supplies oil so that the oil drops on the chain 30. The position of the oil supply portion 55 is not particularly limited, and may be any position that allows the oil to drop on any of the chains included in the internal combustion engine 1. As shown in Fig. 3, the chain cover 60 is located to face the cylinder body portion 10 in the axial direction A of the cam shaft 20, and together with the cylinder body portion 10, houses apart of the cam sprocket 22 and apart of the chain 30. In the cylinder body portion 10 according to the present embodiment, the chain case 17 has an inner surface constituting this housing space. If the cylinder body portion 10 does not have the chain case 17, the cylinder head and the cylinder block have inner surfaces constituting this housing space. The chain cover 60 has a first cover flange surface 61 facing the axial direction A (toward the cylinder body portion 10) and a second cover flange surface 62 facing obliquely upward (toward the head cover 70). The chain cover 60 is connected to the cylinder body portion 10 by contact of the first cover flange surface 61 with the first body flange surface 11. The head cover 70 is connected to both the cylinder body portion 10 and the chain cover 60, and houses another part of the cam sprocket 22 and another part of the chain30. The head cover 70 has a flange surface 71. Fig. 4 is an enlarged partial cross-sectional view of a region IV in Fig. 2. As shown in Figs. 3 and 4, when viewed in the axial direction A, the flange surface 71 is inclined obliquely to the horizontal direction. The flange surface 71 contacts both the cylinder body portion 10 and the chain cover 60 to form a three-surface mating portion T. Specifically, the three-surface mating portion T is formed by contact of the first body flange surface 11 of the cylinder body portion 10 with the first cover flange surface 61 of the chain cover 60, contact of the second body flange surface 12 of the cylinder body portion 10 with the flange surface 71 of the head cover 70, and contact of the second cover flange surface 62 of the chain cover 60 with the flange surface of the head cover 70. When viewed from the three-surface mating portion T, the chain 30 is driven from the lower side D to the upper side U. The head cover 70 further has a gasket 71A (not shown in Fig. 3). Thegasket 71A is disposed in contact with the flange surface 71 of the head cover 70. The gasket 71A is disposed such that, when viewed from the gasket 71A, the flange surface 71 is at least partially located opposite to the housing space that houses the cam sprocket 22 and the chain 30. When viewed from the gasket 71A, a sealing material such as a formed-in-place-gasket (FIPG) may be further provided on the housing space side that houses the cam sprocket 22 and the chain 30. The head cover 70 further has a protrusion 72. The protrusion 72 protrudes, on an inner surface of the head cover 70 constituting the housing space, along a circumferential direction of the cam sprocket 22. Specifically, the protrusion 72 protrudes obliquely downward when viewed in the axial direction A, and more specifically protrudes toward the center C in the horizontal direction and protrudes to the lower side D in a vertical direction. The protrusion 72 is located closer to the housing space than the flange surface 71. When viewed in the axial direction A, the protrusion 72 is located below the chain 30. When viewed from the cam sprocket 22, the protrusion 72 extends along the flange surface 71. The head cover 70 further has an overhang 75 located on the upper side U relative to the protrusion 72 and overhanging into the housing space so that the protrusion 72 protrudes. When viewed in the axial direction A of the cam shaft 20, the overhang 75 has a third surface portion 76 extending along the circumferential direction of the cam sprocket 22, and a fourth surface portion 77 connected to the third surface portion 76 and inclined to the upper side U with increasing distance from the cam sprocket 22.

Although the protrusion 72 and the overhang 75 are formed integrally with the head cover 70, they may be provided by attaching a bracket or the like separate from the head cover 70 to the head cover 70. The rib 80 protrudes, on the housing space side, from at least one of the cylinder body portion 10 and the chain cover 60 toward the cam sprocket 22 when viewed in the axial direction A of the cam shaft 20. Specifically, the rib 80 is provided on both the cylinder body portion 10 (the chain case 17) and the chain cover 60. The rib 80 has a first rib 80A and a second rib 80B. The first rib 80A protrudes from the cylinder body portion 10, and the second rib 80B protrudes from the chain cover 60. Thefirstrib 80A and the second rib 80B are located adjacent to each other in a direction along the flange surface 71. That is, the rib 80 extends along the flange surface 71. When viewed from the cam shaft 20, the rib 80 has a first surface portion 81 located forward in the direction in which the chain 30 is driven, and a second surface portion 82 connected to the first surface portion 81 and located rearward in the direction in which the chain 30 is driven. The first surface portion 81 is located on the lower side D relative to the protrusion 72, and is inclined to the lower side D toward a connection portion 83 with the second surface portion 82 when viewed in the axial direction A of the cam shaft 20. The second surface portion 82 faces a portion 31 of the chain 30 that is located at the lower end of the cam sprocket 22. Theprotrusion72 protrudes toward the connection portion 83 of the first surface portion 81 and the second surface portion 82. Although the rib 80 is formed integrally with the cylinder body portion 10 and the chain cover 60, the rib 80 may be provided by attaching a bracket or the like separate from the cylinder body portion 10 and the chain cover 60 to the cylinder body portion 10 and the chain cover 60. As described above, in the internal combustion engine 1 according to the present embodiment, the head cover 70 has the flange surface 71 and the protrusion 72. The flange surface 71 contacts both the cylinder body portion 10 and the chain cover 60 to form the three-surface mating portion T. The protrusion 72 protrudes, on the inner surface of the head cover 70 constituting the housing space that houses the cam sprocket 22 and the chain 30, along the circumferential direction of the cam sprocket 22. The protrusion 72 is located closer to the housing space than the flange surface 71. As a result, when the chain 30 wound around the cam sprocket 22 is driven upward, the oil scattered from the chain 30 to the head cover 70 and flowing down the inner surface of the head cover 70 under its own weight reaches the protrusion 72. Then, as indicated by a path RI in Fig. 4, the oil is guided by the protrusion 72 so as to pass over the flange surface 71 and drop on an inner surface of the cylinder body portion 10 or the chain cover 60. Thus, contact of the oil with the three-surface mating portion T can be reduced. Moreover, as the protrusion 72 protrudes along the circumferential direction of the cam sprocket 22, an increase in separation distance between the head cover 70 and the cam sprocket 22 can be prevented, and an increase in size of the internal combustion engine 1 can thereby be prevented. In addition, the cylinder body portion 10 includes the cylinder block 15, the cylinder head 16, and the chain case 17. The cylinder head 16 is located on the head cover 70 side when viewed from the cylinder block 15, and pivotally supports the cam shaft 20. The chain case 17 is located on the chain cover side when viewed from the cylinder block 15 and the cylinder head 16, and has an inner surface constituting the housing space in the cylinder body portion 10. As the cylinder body portion 10 includes the chain case 17 in this manner, the position of the three-surface mating portion can be adjusted, and the three-surface mating portion can be formed at an advantageous position to prevent oil leakage. In addition, the internal combustion engine 1 further includes the rib 80 that protrudes, on the housing space side, from at least one of the cylinder body portion 10 and the chain cover 60 toward the cam sprocket 22 when viewed in the axial direction A of the cam shaft 20, and that extends along the flange surface 71. As a result, the oil scattered from a portion of the chain 30 that is driven toward the cam sprocket 22 to the cylinder body portion 10 or the chain cover 60 flows along the inner surface of the cylinder body portion 10 or the chain cover 60 due to a scattering force, and reaches the rib 80. Then, as indicated by a path R2 in Fig. 4, the oil is held back by the rib 80 and splashed back in a direction away from the flange surface71. Thus, contact of the oil with the three-surface mating portion T can be reduced. In addition, the chain 30 is driven from the lower side to the upper side when viewed from the three-surface mating portion T. When viewed from the cam shaft 20, the rib 80 has the first surface portion 81 located forward in the direction in which the chain 30 is driven, and the second surface portion 82 connected to the first surface portion 81 and located rearward in the direction in which the chain 30 is driven. The first surface portion 81 is located below the protrusion 72, and is inclined downward toward the connection portion with the second surface portion 82 when viewed in the axial direction A of the cam shaft 20. As a result, even when the rib 80 is provided, the oil that has dropped on the first surface portion 81 from the protrusion 72 is guided further downward, as indicated by a path R3 in Fig. 4. Thus, contact of the oil on the first surface portion 81 with the flange surface 71 and the three-surface mating portion T is prevented. In addition, the second surface portion 82 faces the portion 31 of the chain 30 that is located at the lower end of the cam sprocket 22. As a result, the oil scattered directly to the flange surface 71 from the above portion 31 of the chain 30 can be effectively held back by the second surface portion 82, and guided downward. Consequently, contact of the oil with the three-surface mating portion T can be prevented. In addition, the protrusion 72 protrudes toward the connection portion 83 of the first surface portion 81 and the second surface portion 82. As a result, the oil flowing on the protrusion 72 at the cam sprocket 22 side can readily pass over the rib 80 when the oil flies from the protrusion 72 along its flow direction, as indicated by a path R4 in Fig. 4. Thus, the oil can be prevented from staying on the first surface portion 81. Consequently, contact of the oil with the three surface mating portion T can be prevented. In addition, the head cover 70 has the overhang 75 located above the protrusion 72 and overhanging into the housing space so that the protrusion 72 protrudes. When viewed in the axial direction A of the cam shaft 20, the overhang 75 has the third surface portion 76 extending along the circumferential direction of the cam sprocket 22, and the fourth surface portion 77 connected to the third surface portion 76 and inclined upward with increasing distance from the cam sprocket 22. As a result, the oil that has adhered to the fourth surface portion 77 can be guided to the third surface portion 76, and the oil on the third surface portion 76 can be guided further downward. Consequently, the oil can be prevented from staying on the inner surface of the head cover 70 above the protrusion 72. In addition, when viewed in the axial direction A of the cam shaft 20, the protrusion 72 is located below the chain 30. As a result, the oil dropping directly from the chain 30 can also be received by the protrusion 72 and guided downward. Consequently, contact of the oil with the flange surface 71 and the three-surface mating portion T can be prevented. (Second Embodiment) An internal combustion engine according to a second embodiment of the present disclosure will be described hereinafter. The internal combustion engine according to the second embodiment of the present disclosure is mainly different from the first embodiment in the shape of the protrusion. Thus, the description of a configuration similar to that of the internal combustion engine 1 according to the first embodiment of the present disclosure will not be repeated. Fig. 5 is a partial cross-sectional view showing the internal combustion engine according to the second embodiment. As shown in Fig. 5, in an internal combustion engine la according to the second embodiment of the present disclosure, when viewed from the portion 31 of the chain 30 that is located at the lower end of the cam sprocket 22, a protrusion 72a protrudes to cover the three-surface mating portion T. As a result, contact of the oil flowing down the inner surface of the head cover

70 with the three-surface mating portion T can be prevented, and furthermore, the oil scattered when the direction in which the chain 30 is driven is directed from the above portion 31 to the upper side U can be received by the protrusion 72a and guided to the lower side D. Consequently, the oil can be prevented from reaching the flange surface 71 that forms the three-surface mating portion T. In addition, the protrusion 72a extends along an inner surface of at least one of the cylinder body portion 10 and the chain cover 60 constituting the housing space. As a result, the oil flowing down the inner surface of the head cover 70 can be more readily guided to the inner surface of at least one of the cylinder body portion 10 and the chain cover 60, and therefore, contact of the oil with the three-surface mating portion T can be further prevented. Although the internal combustion engine l a according to the second embodiment does not include a rib because the contact of the oil with the three-surface mating portion T can be sufficiently prevented by the protrusion 72a, the internal combustion engine la may include a rib 80 similar to that of the first embodiment. Although the embodiments of the present disclosure have been described, it should be understood that the embodiments disclosed herein are illustrative and non restrictive in every respect. The scope of the present disclosure is defined by the scope of the claims, and is intended to include any modifications within the scope and meaning equivalent to the scope of the claims.

Claims (10)

WHAT IS CLAIMED IS:

1. An internal combustion engine comprising: a cylinder body portion; a cam shaft that is provided in the cylinder body portion and that has an axial end portion protruding from a side surface of the cylinder body portion; a cam sprocket that is provided on the axial end portion of the cam shaft and that causes rotation of the cam shaft; a chain that is wound around the cam sprocket and that causes rotation of the cam sprocket; a chain cover that is located to face the cylinder body portion in an axial direction of the cam shaft, and that, together with the cylinder body portion, houses a part of the cam sprocket and a part of the chain; and a head cover that is connected to both the cylinder body portion and the chain cover and that houses another part of the cam sprocket and another part of the chain, the head cover having a flange surface contacting both the cylinder body portion and the chain cover to form a three-surface mating portion, and a protrusion protruding, on an inner surface of the head cover constituting a housing space that houses the cam sprocket and the chain, along a circumferential direction of the cam sprocket, the protrusion being located closer to the housing space than the flange surface.

2. The internal combustion engine according to claim 1, wherein the cylinder body portion includes a cylinder block, a cylinder head that is located on the head cover side when viewed from the cylinder block and that pivotally supports the cam shaft, and a chain case that is located on the chain cover side when viewed from the cylinder block and the cylinder head and that has an inner surface constituting the housing space in the cylinder body portion.

3. The internal combustion engine according to claim 1 or 2, further comprising a rib that protrudes, on the housing space side, from at least one of the cylinder body portion and the chain cover toward the cam sprocket when viewed in the axial direction of the cam shaft, and that extends along the flange surface.

4. The internal combustion engine according to claim 3, wherein the chain is driven from a lower side to an upper side when viewed from the three-surface mating portion, when viewed from the cam shaft, the rib has a first surface portion located forward in a direction in which the chain is driven, and a second surface portion connected to the first surface portion and located rearward in the direction in which the chain is driven, and the first surface portion is located below the protrusion, and is inclined downward toward a connection portion with the second surface portion when viewed in the axial direction of the cam shaft.

5. The internal combustion engine according to claim 4, wherein the second surface portion faces a portion of the chain that is located at a lower end of the cam sprocket.

6. The internal combustion engine according to claim 4 or 5, wherein the protrusion protrudes toward the connection portion of the first surface portion and the second surface portion.

7. The internal combustion engine according to any one of claims 1 to 6, wherein the head cover has an overhang located above the protrusion and overhanging into the housing space so that the protrusion protrudes, and when viewed in the axial direction of the cam shaft, the overhang has a third surface portion extending along the circumferential direction of the cam sprocket, and a fourth surface portion connected to the third surface portion and inclined upward with increasing distance from the cam sprocket.

8. The internal combustion engine according to any one of claims 1 to 7, wherein when viewed in the axial direction of the cam shaft, the protrusion is located below the chain.

9. The internal combustion engine according to any one of claims 1 to 8, wherein when viewed from the portion of the chain that is located at the lower end of the cam sprocket, the protrusion protrudes to cover the three-surface mating portion.

10. The internal combustion engine according to claim 9, wherein the protrusion extends along an inner surface of at least one of the cylinder body portion and the chain cover constituting the housing space.