INTERNAL COMBUSTION ENGINE

Abstract

 [Object]
To provide an internal combustion engine capable of suppressing vibration and deformation of a chain casing.
[Solution]
A chain casing 20 includes a cylindrical intake side cylinder portion 23 bulging in a crank shaft direction and allowing an intake hydraulic control valve 15 to be inserted thereinto, a cylindrical exhaust side cylinder portion 24 bulging in the crank shaft direction and allowing an exhaust hydraulic control valve 16 to be inserted thereinto, and an intake side fastening boss portion 25 and an exhaust side fastening boss portion 26 arranged below a bulging portion 21 and attaching the chain casing to a cylinder head 3. A lower portion of the bulging portion 21 is connected to upper portions of the intake side cylinder portion 23 and the exhaust side cylinder portion 24. An upper portion of the intake side fastening boss portion 25 is connected to a lower portion of the intake side cylinder portion 23. An upper portion of the exhaust side fastening boss portion 26 is connected to a lower portion of the exhaust side cylinder portion 24.

Description

[Technical Field]

[0001] This invention relates to an internal combustion engine.

[Background of the Invention]

[0002] In an internal combustion engine including a variable valve timing mechanism, a technique of forming a bulging portion covering the variable valve timing mechanism in a chain casing is known (see JP 4340908 B2). In the internal combustion engine described in JP 4340908 B2, an oil control valve that controls hydraulic oil to the variable valve timing mechanism is provided at the lower portion of the bulging portion.

[Prior Art]

[Patent Literature]

[0003] [Patent Literature 1] JP 4340908 B2

[Summary of the Invention]

[Problem to be solved by the Invention]

[0004] However, in the technique described in Patent Literature 1, since the internal space and the surface area of the bulging portion in the chain casing are large and the number of positions in which the bulging portion is directly supported by a cylinder head is small, it has been required to suppress vibration and deformation of the chain casing due to insufficient rigidity of the bulging portion.

[0005] This invention has been made in view of the above-described circumstances and an object of this invention is to provide an internal combustion engine capable of suppressing vibration and deformation of a chain casing.

[Means to solve the problem]

[0006] According to aspects of this invention, there is provided an internal combustion engine including: a variable valve timing mechanism configured by winding a timing chain thereon; a hydraulic control valve controlling a hydraulic oil supplied to the variable valve timing mechanism; and a chain casing fixed to a cylinder head to cover the timing chain and the variable valve timing mechanism, wherein a bulging portion bulging in a crank shaft direction and covering the variable valve timing mechanism is formed in the chain casing, wherein the hydraulic control valve is disposed below the bulging portion, wherein the hydraulic control valve includes an intake hydraulic control valve and an exhaust hydraulic control valve, wherein the chain casing includes a cylindrical intake side cylinder portion bulging in the crank shaft direction and allowing the intake hydraulic control valve to be inserted thereinto, a cylindrical exhaust side cylinder portion bulging in the crank shaft direction and allowing the exhaust hydraulic control valve to be inserted thereinto, and an intake side fastening boss portion and an exhaust side fastening boss portion arranged below the bulging portion and attaching the chain casing to the cylinder head, wherein a lower portion of the bulging portion is connected to upper portions of the intake side cylinder portion and the exhaust side cylinder portion, wherein an upper portion of the intake side fastening boss portion is connected to a lower portion of the intake side cylinder portion, and wherein an upper portion of the exhaust side fastening boss portion is connected to a lower portion of the exhaust side cylinder portion.

[Effect of the Invention]

[0007] In this way, according to this invention, it is possible to provide an internal combustion engine capable of suppressing vibration and deformation of a chain casing.

[Brief description of figures]

[0008] 

[Fig. 1] Fig. 1 is a front view of an internal combustion engine according to an embodiment of this invention.

[Fig. 2] Fig. 2 is a side view of the internal combustion engine according to an embodiment of this invention.

[Fig. 3] Fig. 3 is a perspective view of a chain casing of the internal combustion engine according to an embodiment of this invention.

[Fig. 4] Fig. 4 is a front view of the chain casing of the internal combustion engine according to an embodiment of this invention.

[Fig. 5] Fig. 5 is a side view of the chain casing of the internal combustion engine according to an embodiment of this invention.

[Fig. 6] Fig. 6 is a cross-sectional view when viewed from a direction VI-VI of Fig. 1.

[Embodiment(s) of the Invention]

[0009] An internal combustion engine according to embodiments of this invention is an internal combustion engine including: a variable valve timing mechanism configured by winding a timing chain thereon; a hydraulic control valve controlling a hydraulic oil supplied to the variable valve timing mechanism; and a chain casing fixed to a cylinder head to cover the timing chain and the variable valve timing mechanism, wherein a bulging portion bulging in a crank shaft direction and covering the variable valve timing mechanism is formed in the chain casing, wherein the hydraulic control valve is disposed below the bulging portion, wherein the hydraulic control valve includes an intake hydraulic control valve and an exhaust hydraulic control valve, wherein the chain casing includes a cylindrical intake side cylinder portion bulging in the crank shaft direction and allowing the intake hydraulic control valve to be inserted thereinto, a cylindrical exhaust side cylinder portion bulging in the crank shaft direction and allowing the exhaust hydraulic control valve to be inserted thereinto, and an intake side fastening boss portion and an exhaust side fastening boss portion arranged below the bulging portion and for attaching the chain casing to the cylinder head, wherein a lower portion of the bulging portion is connected to upper portions of the intake side cylinder portion and the exhaust side cylinder portion, wherein an upper portion of the intake side fastening boss portion is connected to a lower portion of the intake side cylinder portion, and wherein an upper portion of the exhaust side fastening boss portion is connected to a lower portion of the exhaust side cylinder portion.

[0010] Accordingly, the internal combustion engine according to embodiments of this invention can suppress the vibration and the deformation of the chain casing.

[Embodiments]

[0011] Hereinafter, an internal combustion engine according to an embodiment of this invention will be described with reference to the drawings. Figs. 1 to 6 are diagrams showing the internal combustion engine according to an embodiment of this invention.

[0012] In Figs. 1 to 6, the up, down, front, rear, right, and left directions are based on the state in which the internal combustion engine separated from the vehicle is upright so that the cylinder head is directly above the crank shaft. Further, the front to rear direction is expressed to coincide with the front to rear direction of the vehicle equipped with the internal combustion engine.

[0013] First, a configuration will be described. In Figs. 1 and 2, an internal combustion engine 1 mounted on the vehicle includes a cylinder block 2. The cylinder block 2 is provided with a crank shaft 2A and the crank shaft 2A extends in the front to rear direction.

[0014] The cylinder block 2 is provided with three cylinders (not shown) arranged in the front to rear direction and the cylinders extend in the up to down direction. The internal combustion engine 1 of this embodiment is an FR (front engine-rear drive) type vertical engine. Additionally, the internal combustion engine 1 is not limited to an in-line engine and may be, for example, a V-type engine. Then, the number of cylinders is not limited to three.

[0015] A cylinder head 3 is provided on the upper side of the cylinder block 2. The cylinder head 3 includes an intake port 3A (see Fig. 2) which takes air, an exhaust port 3B (see Fig. 1) which discharges an exhaust gas, an intake valve, and an exhaust valve or the like (not shown). The intake port 3A opens to the right wall of the cylinder head 3 and the exhaust port 3B opens to the left wall of the cylinder head 3.

[0016] A cylinder head cover 4 is provided on the upper side of the cylinder head 3. An oil pan 5 is provided below the cylinder block 2 and the oil pan 5 stores oil for lubricating the internal combustion engine 1.

[0017] The internal combustion engine 1 is installed below a floor panel of the vehicle (not shown). The cylinder block 2 is installed so that the center lines of the plurality of cylinders are inclined with respect to the vertical direction of the vehicle. Specifically, the cylinder block 2 is installed so that the upper portion thereof is located on the left side and the lower portion is located on the right side by inclining the center line in the left to right direction with respect to the vertical direction.

[0018] An undercover 1A is provided below the internal combustion engine 1. The undercover 1A extends in the horizontal direction and covers the internal combustion engine 1 from below. A bottom surface 5A of the oil pan 5 is located at the bottom portion of the internal combustion engine 1 in a vehicle mounted state. This bottom surface 5A is inclined with respect to the left to right direction of the internal combustion engine 1 itself to extend in parallel to the undercover 1A in the vehicle mounted state.

[0019] In this way, the internal combustion engine 1 is mounted on the front portion of the vehicle while being largely inclined. Therefore, in the vehicle mounted state, the right side surface (intake side) of the internal combustion engine 1 faces the upper side of the vehicle and the left side surface (exhaust side) of the internal combustion engine 1 faces the lower side of the vehicle.

[0020] The internal combustion engine 1 includes a variable valve timing mechanism 11 on which a timing chain 10 is wound, an intake hydraulic control valve 15 and an exhaust hydraulic control valve 16 which have a cylindrical shape and serve as a hydraulic control valve controlling a hydraulic oil supplied to the variable valve timing mechanism 11, and a chain casing 20 which is fixed to the cylinder head 3 to cover the timing chain 10 and the variable valve timing mechanism 11.

[0021] The variable valve timing mechanism 11 includes an intake side variable valve timing mechanism 12 which changes an opening and closing timing of the intake valve and an exhaust side variable valve timing mechanism 13 which changes an opening and closing timing of the exhaust valve.

[0022] The intake side variable valve timing mechanism 12 is disposed on the right side of the upper end portion of the cylinder head 3 and the exhaust side variable valve timing mechanism 13 is disposed on the left side of the upper end portion of the cylinder head 3.

[0023] The edge portion of the chain casing 20 is fixed to the cylinder head 3 by a plurality of bolts.

[0024] A bulging portion 21 is formed on the upper portion of the chain casing 20 and the bulging portion 21 bulges in the crank shaft direction (forward) to cover the variable valve timing mechanism 11. The intake hydraulic control valve 15 and the exhaust hydraulic control valve 16 are arranged below the bulging portion 21.

[0025] Here, in this embodiment, the internal space and the surface area of the bulging portion 21 in the chain casing 20 are large and the number of positions in which the bulging portion 21 is directly supported by the cylinder head 3 is small.

[0026] Therefore, it is preferable to improve the rigidity and strength of the chain casing 20 so that the chain casing 20 is not vibrated and deformed due to the insufficient rigidity of the bulging portion 21. On the other hand, the internal combustion engine 1 of this embodiment is mounted on the vehicle in a largely inclined posture by being supported by a vehicle body in a portion other than the chain casing 20. Therefore, a mount attachment portion capable of improving strength in order to support the internal combustion engine 1 by the vehicle body is not formed in the vicinity of the bulging portion 21 of the chain casing 20. Therefore, it is preferable that the rigidity and strength of the chain casing 20 can be ensured even when the mount attachment portion is not formed.

[0027] Here, in this embodiment, the rigidity and strength of the bulging portion 21 of the chain casing 20 and the peripheral portion thereof are improved by the arrangement of an intake side cylinder portion 23 and an exhaust side cylinder portion 24 to be described later, the connection structure of each portion, or the like.

[0028]  In Figs. 3 and 4, the chain casing 20 includes the cylindrical intake side cylinder portion 23 which bulges in the crank shaft direction and into which the intake hydraulic control valve 15 is inserted and the cylindrical exhaust side cylinder portion 24 which bulges in the crank shaft direction and into which the exhaust hydraulic control valve 16 is inserted.

[0029] The intake hydraulic control valve 15 and the exhaust hydraulic control valve 16 are respectively inserted into the intake side cylinder portion 23 and the exhaust side cylinder portion 24 from the left side (the upper side in the vehicle mounted state). Therefore, since the insertion directions of the intake hydraulic control valve 15 and the exhaust hydraulic control valve 16 are the same as each other, the insertion work can be facilitated.

[0030] Further, since the intake hydraulic control valve 15 and the exhaust hydraulic control valve 16 are arranged above the intake side cylinder portion 23 and the exhaust side cylinder portion 24 in the vehicle mounted state, it is possible to prevent a foreign mater from entering the intake hydraulic control valve 15 and the exhaust hydraulic control valve 16 even when the foreign matter or the like mixed with the hydraulic oil precipitates.

[0031] The chain casing 20 includes an intake side fastening boss portion 25 and an exhaust side fastening boss portion 26 for attaching the chain casing 20 to the cylinder head 3. The intake side fastening boss portion 25 and the exhaust side fastening boss portion 26 are arranged below the bulging portion 21.

[0032] The lower portion of the bulging portion 21 is connected to the upper portions of the intake side cylinder portion 23 and the exhaust side cylinder portion 24. The upper portion of the intake side fastening boss portion 25 is connected to the lower portion of the intake side cylinder portion 23. The upper portion of the exhaust side fastening boss portion 26 is connected to the lower portion of the exhaust side cylinder portion 24.

[0033] The upper surface of the cylinder head 3 forms a joint surface joined to the cylinder head cover 4. The upper surface of the cylinder head 3 extends in a planar shape in the front to rear direction and the left to right direction.

[0034] The intake hydraulic control valve 15, the exhaust hydraulic control valve 16, the intake side cylinder portion 23, and the exhaust side cylinder portion 24 extend in parallel to the upper surface of the cylinder head 3. Further, the intake hydraulic control valve 15, the exhaust hydraulic control valve 16, the intake side cylinder portion 23, and the exhaust side cylinder portion 24 are arranged side by side in parallel to the upper surface of the cylinder head 3.

[0035] That is, the intake hydraulic control valve 15, the exhaust hydraulic control valve 16, the intake side cylinder portion 23, and the exhaust side cylinder portion 24 are arranged in the chain casing 20 in a posture extending in the left to right direction and in a mutual positional relationship arranged in the left to right direction.

[0036] The intake side fastening boss portion 25 and the exhaust side fastening boss portion 26 are arranged side by side in parallel to the upper surface of the cylinder head 3. The intake side fastening boss portion 25 and the exhaust side fastening boss portion 26 are formed to protrude in the crank shaft direction (forward) at least from the intake side cylinder portion 23.

[0037] The intake side cylinder portion 23 and the exhaust side cylinder portion 24 are arranged side by side at different positions in the crank shaft direction. In other words, the intake side cylinder portion 23 and the exhaust side cylinder portion 24 are arranged in parallel in the crank shaft direction. In this embodiment, the exhaust side cylinder portion 24 is disposed adjacent to the front side of the intake side cylinder portion 23.

[0038] Further, when the chain casing 20 is viewed along the crank shaft direction (see Fig. 3), the exhaust side cylinder portion 24 is disposed to be more offset to the exhaust side (left side) than the intake side cylinder portion 23. In this embodiment, the exhaust side cylinder portion 24 is disposed adjacent to the left side of the intake side cylinder portion 23. In this way, in this embodiment, the exhaust side cylinder portion 24 is disposed adjacent to the front side and the left side of the intake side cylinder portion 23.

[0039] In Figs. 3, 4, and 6, the chain casing 20 includes a cylindrical oil passage forming portion 27 and the oil passage forming portion 27 extends in a direction orthogonal to the crank shaft direction to pass through the lower portion of the intake side fastening boss portion 25 and the lower portion of the exhaust side fastening boss portion 26. An oil passage 27A through which the hydraulic oil flows is formed inside the oil passage forming portion 27. The oil passage forming portion 27 is connected to the lower portion of the intake side fastening boss portion 25 and the lower portion of the exhaust side fastening boss portion 26.

[0040] The chain casing 20 includes a reinforcement rib 28 provided below the intake side cylinder portion 23 and the reinforcement rib 28 extends in the axial direction of the intake side cylinder portion 23. The reinforcement rib 28 connects the intake side cylinder portion 23, the exhaust side cylinder portion 24, and the intake side fastening boss portion 25.

[0041] Specifically, the reinforcement rib 28 extends in the axial direction of the intake side cylinder portion 23 along the lower portion of the intake side cylinder portion 23 and the upper portion of the reinforcement rib 28 is connected to the lower portion of the intake side cylinder portion 23. Further, the left end portion of the reinforcement rib 28 is connected to the lower portion of the exhaust side cylinder portion 24. Then, the lower portion of the reinforcement rib 28 is connected to the upper portion of the intake side fastening boss portion 25.

[0042] In Figs. 3, 4, 5, and 6, the chain casing 20 includes a boss portion 34 provided at the lower portion of the right end portion of the intake side cylinder portion 23. The boss portion 34 is provided below the bulging portion 21. A leg portion 15A of the intake hydraulic control valve 15 is fastened to the boss portion 34. The leg portion 15A extends in the crank shaft direction (forward) and downward at the left end portion of the intake hydraulic control valve 15.

[0043] The chain casing 20 includes a boss portion 35 provided at the upper portion of the right end portion of the exhaust side cylinder portion 24. The boss portion 35 is provided at the bulging portion 21. A leg portion 16A of the exhaust hydraulic control valve 16 is fastened to the boss portion 35. The leg portion 16A extends in the crank shaft direction (forward) and upward at the left end portion of the exhaust hydraulic control valve 16.

[0044] An intake side rib 31, an exhaust side first rib 32, and an exhaust side second rib 33 are formed on the surface of the chain casing 20 to protrude in the crank shaft direction (forward). A boss portion 37 which extends in the crank shaft direction (forward) is formed in the vicinity of the left end portion of the bulging portion 21 of the chain casing 20. A boss portion 36 which extends in the crank shaft direction (forward) is formed at the upper end portion of the chain casing 20.

[0045] The intake side rib 31 is provided in the vicinity of the right end portion of the chain casing 20. The intake side rib 31 extends obliquely in the right down direction from the boss portion 34 to the right end portion below the bulging portion 21 of the chain casing 20. The intake side rib 31 reinforces the boss portion 34 by distributing a load acting on the boss portion 34 toward the right end portion of the chain casing 20.

[0046] The exhaust side first rib 32 is provided in the vicinity of the left end portion of the bulging portion 21 of the chain casing 20. The exhaust side first rib 32 extends obliquely in the left up direction from the left end portion of the exhaust side cylinder portion 24 to the boss portion 37. The exhaust side first rib 32 is connected to the left end portion of the exhaust side cylinder portion 24 and the boss portion 37.

[0047] Thus, the exhaust side cylinder portion 24 and the boss portion 37 are connected by the exhaust side first rib 32. Accordingly, a load acting on the exhaust side cylinder portion 24 is distributed to the chain casing 20 through the boss portion 37.

[0048] The exhaust side second rib 33 is provided in the vicinity of the upper end portion of the chain casing 20. The exhaust side second rib 33 extends obliquely rightward and upward from the boss portion 35 to the boss portion 36. The exhaust side second rib 33 is connected to the boss portion 35 and the boss portion 36. Thus, the boss portion 35 and the boss portion 36 are connected by the exhaust side second rib 33. Accordingly, a load acting on the boss portion 35 is distributed to the boss portion 36 through the exhaust side second rib 33.

[0049] As described above, in this embodiment, the chain casing 20 includes the cylindrical intake side cylinder portion 23 which bulges in the crank shaft direction and into which the intake hydraulic control valve 15 is inserted and the cylindrical exhaust side cylinder portion 24 which bulges in the crank shaft direction and into which the exhaust hydraulic control valve 16 is inserted. Further, the chain casing 20 includes the intake side fastening boss portion 25 and the exhaust side fastening boss portion 26 which are arranged below the bulging portion 21 and for attaching the chain casing 20 to the cylinder head 3. Then, the lower portion of the bulging portion 21 is connected to the upper portions of the intake side cylinder portion 23 and the exhaust side cylinder portion 24, the upper portion of the intake side fastening boss portion 25 is connected to the lower portion of the intake side cylinder portion 23, and the upper portion of the exhaust side fastening boss portion 26 is connected to the lower portion of the exhaust side cylinder portion 24.

[0050] In this way, since the lower portion of the bulging portion 21 is connected to the upper portions of the cylindrical intake side cylinder portion 23 and the exhaust side cylinder portion 24, the intake side cylinder portion 23 and the exhaust side cylinder portion 24 can reinforce the bulging portion 21 and improve the rigidity of the bulging portion 21.

[0051] Further, since the intake side cylinder portion 23 and the exhaust side cylinder portion 24 are respectively connected to the intake side fastening boss portion 25 and the exhaust side fastening boss portion 26 having high rigidity, it is possible to reinforce the lower portions of the intake side cylinder portion 23 and the exhaust side cylinder portion 24 in the chain casing 20.

[0052] Accordingly, it is possible to suppress the vibration and the deformation particularly around the bulging portion 21 of the chain casing 20. Further, since the surface rigidity of the chain casing 20 can be improved, it is possible to effectively block the radiated sound of the internal combustion engine 1.

[0053] As a result, it is possible to suppress the vibration and the deformation of the chain casing 20.

[0054] Further, in this embodiment, the intake side cylinder portion 23 and the exhaust side cylinder portion 24 are arranged side by side at different positions in the crank shaft direction.

[0055] Accordingly, as compared with a case in which the intake side cylinder portion 23 and the exhaust side cylinder portion 24 are arranged at the same position in the crank shaft direction, it is possible to decrease the size of the intake side cylinder portion 23 and the exhaust side cylinder portion 24 in the up to down direction and to dispose the fastening boss portion at a position closer to the cylinder head cover 4 above the chain casing 20. Thus, since it is possible to arrange the bulging portion 21 and the fastening boss portion at the closer position and to rigidly connect the bulging portion 21, the cylinder portion, and the fastening boss, it is possible to improve the rigidity of the chain casing 20 and thus to suppress the vibration and the deformation of the chain casing 20.

[0056] Further, since the intake side cylinder portion 23 and the exhaust side cylinder portion 24 are arranged in parallel, it is possible to compactly arrange members such as the intake side cylinder portion 23 and the exhaust side cylinder portion 24 on the surface of the chain casing 20 and to avoid a large change in the arrangement of other members.

[0057] Further, in this embodiment, the exhaust side cylinder portion 24 is disposed closer to the exhaust side than the intake side cylinder portion 23 when the chain casing 20 is viewed along the crank shaft direction.

[0058] Accordingly, since the chain casing 20 is provided with a step in which the exhaust side cylinder portion 24 is disposed closer to the exhaust side than the intake side cylinder portion 23, it is possible to improve the rigidity of the chain casing 20 and to suppress the vibration and the deformation of the chain casing 20.

[0059] Further, since the intake side cylinder portion 23 and the exhaust side cylinder portion 24 are linearly arranged at the lower portion of the bulging portion 21, it is possible to suppress the vibration of the bulging portion 21 and to improve the surface rigidity of the chain casing 20. Therefore, it is possible to effectively block the radiated sound of the internal combustion engine 1 by the chain casing 20.

[0060] Further, in this embodiment, the chain casing 20 includes the reinforcement rib 28 which is provided below the intake side cylinder portion 23 to extend in the axial direction of the intake side cylinder portion 23 and the reinforcement rib 28 connects the intake side cylinder portion 23, the exhaust side cylinder portion 24, and the intake side fastening boss portion 25.

[0061] Accordingly, since the intake side cylinder portion 23, the exhaust side cylinder portion 24, and the intake side fastening boss portion 25 are connected by the reinforcement rib 28 below the bulging portion 21, it is possible to more rigidly reinforce the lower portion of the bulging portion 21. Accordingly, it is possible to suppress the vibration and the deformation in the periphery of the bulging portion 21 of the chain casing 20.

[0062] Further, in this embodiment, the chain casing 20 includes the cylindrical oil passage forming portion 27 which extends in a direction orthogonal to the crank shaft direction to pass through the lower portion of the intake side fastening boss portion 25 and the lower portion of the exhaust side fastening boss portion 26 and the oil passage forming portion 27 is connected to the lower portion of the intake side fastening boss portion 25 and the lower portion of the exhaust side fastening boss portion 26.

[0063] Accordingly, since the oil passage forming portion 27 having a cylindrical shape and high rigidity is connected to the lower portion of the intake side fastening boss portion 25 and the lower portion of the exhaust side fastening boss portion 26 below the bulging portion 21, it is possible to reinforce a portion in the vicinity of the lower portion of the bulging portion 21 in the chain casing 20 and to improve surface rigidity. Therefore, it is possible to suppress the vibration and the deformation in the portion in the vicinity of the lower portion of the bulging portion 21 of the chain casing 20. Further, since the surface rigidity of the chain casing 20 is improved, it is possible to effectively block the radiated sound of the internal combustion engine 1 by the chain casing 20.

[0064] While embodiments of this invention have been described, it is apparent that some artisan could have made changes without departing from the scope of this invention. It is intended that any and all such modifications and equivalents are involved in the appended claims.

(DESCRIPTION OF REFERENCE NUMERALS)

[0065] 1 ... Internal combustion engine, 3 ... Cylinder head, 10 ... Timing chain, 11 ... Variable valve timing mechanism, 15 ... Intake hydraulic control valve, 16 ... Exhaust hydraulic control valve, 20 ... Chain casing, 21 ... Bulging portion, 23 ... Intake side cylinder portion, 24 ... Exhaust side cylinder portion, 25 ... Intake side fastening boss portion, 26 ... Exhaust side fastening boss portion, 27 ... Oil passage forming portion, 28 ... Reinforcement rib

Claims

1. An internal combustion engine comprising:

a variable valve timing mechanism configured by winding a timing chain thereon;

a hydraulic control valve controlling a hydraulic oil supplied to the variable valve timing mechanism; and

a chain casing fixed to a cylinder head to cover the timing chain and the variable valve timing mechanism,

wherein a bulging portion bulging in a crank shaft direction and covering the variable valve timing mechanism is formed in the chain casing,

wherein the hydraulic control valve is disposed below the bulging portion,

wherein the hydraulic control valve includes an intake hydraulic control valve and an exhaust hydraulic control valve,

wherein the chain casing includes a cylindrical intake side cylinder portion bulging in the crank shaft direction and allowing the intake hydraulic control valve to be inserted thereinto, a cylindrical exhaust side cylinder portion bulging in the crank shaft direction and allowing the exhaust hydraulic control valve to be inserted thereinto, and an intake side fastening boss portion and an exhaust side fastening boss portion arranged below the bulging portion and attaching the chain casing to the cylinder head,

wherein a lower portion of the bulging portion is connected to upper portions of the intake side cylinder portion and the exhaust side cylinder portion,

wherein an upper portion of the intake side fastening boss portion is connected to a lower portion of the intake side cylinder portion, and

wherein an upper portion of the exhaust side fastening boss portion is connected to a lower portion of the exhaust side cylinder portion.

2. The internal combustion engine according to claim 1,
wherein the intake side cylinder portion and the exhaust side cylinder portion are arranged side by side at different positions in the crank shaft direction.

3. The internal combustion engine according to claim 1 or 2,
wherein when the chain casing is viewed along the crank shaft direction, the exhaust side cylinder portion is disposed closer to an exhaust side than the intake side cylinder portion.

4. The internal combustion engine according to any one of claims 1 to 3,

wherein the chain casing includes a reinforcement rib provided below the intake side cylinder portion to extend in an axial direction of the intake side cylinder portion, and

wherein the reinforcement rib connects the intake side cylinder portion, the exhaust side cylinder portion, and the intake side fastening boss portion.

5. The internal combustion engine according to any one of claims 1 to 4,

wherein the chain casing includes a cylindrical oil passage forming portion extending in a direction orthogonal to the crank shaft direction to pass through a lower portion of the intake side fastening boss portion and a lower portion of the exhaust side fastening boss portion, and

wherein the oil passage forming portion is connected to the lower portion of the intake side fastening boss portion and the lower portion of the exhaust side fastening boss portion.

Drawing