Patent Description:
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 <CIT>). In the internal combustion engine described in <CIT>, an oil control valve that controls hydraulic oil to the variable valve timing mechanism is provided at the lower portion of the bulging portion.

[Patent Literature <NUM>] <CIT>. <CIT> relates to a variable valve timing mechanism-equipped engine.

However, in the technique described in Patent Literature <NUM>, 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.

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.

According to aspects of this invention, there is provided an internal combustion engine according to claim <NUM>.

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.

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.

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

Hereinafter, an internal combustion engine according to an embodiment of this invention will be described with reference to the drawings. <FIG> are diagrams showing the internal combustion engine according to an embodiment of this invention.

In <FIG>, 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.

First, a configuration will be described. In <FIG> and <FIG>, an internal combustion engine <NUM> mounted on the vehicle includes a cylinder block <NUM>. The cylinder block <NUM> is provided with a crank shaft 2A and the crank shaft 2A extends in the front to rear direction.

The cylinder block <NUM> 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 <NUM> of this embodiment is an FR (front engine-rear drive) type vertical engine. Additionally, the internal combustion engine <NUM> 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.

A cylinder head <NUM> is provided on the upper side of the cylinder block <NUM>. The cylinder head <NUM> includes an intake port 3A (see <FIG>) which takes air, an exhaust port 3B (see <FIG>) 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 <NUM> and the exhaust port 3B opens to the left wall of the cylinder head <NUM>.

A cylinder head cover <NUM> is provided on the upper side of the cylinder head <NUM>. An oil pan <NUM> is provided below the cylinder block <NUM> and the oil pan <NUM> stores oil for lubricating the internal combustion engine <NUM>.

The internal combustion engine <NUM> is installed below a floor panel of the vehicle (not shown). The cylinder block <NUM> 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 <NUM> 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.

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

In this way, the internal combustion engine <NUM> 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 <NUM> faces the upper side of the vehicle and the left side surface (exhaust side) of the internal combustion engine <NUM> faces the lower side of the vehicle.

The internal combustion engine <NUM> includes a variable valve timing mechanism <NUM> on which a timing chain <NUM> is wound, an intake hydraulic control valve <NUM> and an exhaust hydraulic control valve <NUM> which have a cylindrical shape and serve as a hydraulic control valve controlling a hydraulic oil supplied to the variable valve timing mechanism <NUM>, and a chain casing <NUM> which is fixed to the cylinder head <NUM> to cover the timing chain <NUM> and the variable valve timing mechanism <NUM>.

The variable valve timing mechanism <NUM> includes an intake side variable valve timing mechanism <NUM> which changes an opening and closing timing of the intake valve and an exhaust side variable valve timing mechanism <NUM> which changes an opening and closing timing of the exhaust valve.

The intake side variable valve timing mechanism <NUM> is disposed on the right side of the upper end portion of the cylinder head <NUM> and the exhaust side variable valve timing mechanism <NUM> is disposed on the left side of the upper end portion of the cylinder head <NUM>.

The edge portion of the chain casing <NUM> is fixed to the cylinder head <NUM> by a plurality of bolts.

A bulging portion <NUM> is formed on the upper portion of the chain casing <NUM> and the bulging portion <NUM> bulges in the crank shaft direction (forward) to cover the variable valve timing mechanism <NUM>. The intake hydraulic control valve <NUM> and the exhaust hydraulic control valve <NUM> are arranged below the bulging portion <NUM>.

Here, in this embodiment, the internal space and the surface area of the bulging portion <NUM> in the chain casing <NUM> are large and the number of positions in which the bulging portion <NUM> is directly supported by the cylinder head <NUM> is small.

Therefore, it is preferable to improve the rigidity and strength of the chain casing <NUM> so that the chain casing <NUM> is not vibrated and deformed due to the insufficient rigidity of the bulging portion <NUM>. On the other hand, the internal combustion engine <NUM> 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 <NUM>. Therefore, a mount attachment portion capable of improving strength in order to support the internal combustion engine <NUM> by the vehicle body is not formed in the vicinity of the bulging portion <NUM> of the chain casing <NUM>. Therefore, it is preferable that the rigidity and strength of the chain casing <NUM> can be ensured even when the mount attachment portion is not formed.

Here, in this embodiment, the rigidity and strength of the bulging portion <NUM> of the chain casing <NUM> and the peripheral portion thereof are improved by the arrangement of an intake side cylinder portion <NUM> and an exhaust side cylinder portion <NUM> to be described later, the connection structure of each portion, or the like.

In <FIG> and <FIG>, the chain casing <NUM> includes the cylindrical intake side cylinder portion <NUM> which bulges in the crank shaft direction and into which the intake hydraulic control valve <NUM> is inserted and the cylindrical exhaust side cylinder portion <NUM> which bulges in the crank shaft direction and into which the exhaust hydraulic control valve <NUM> is inserted.

The intake hydraulic control valve <NUM> and the exhaust hydraulic control valve <NUM> are respectively inserted into the intake side cylinder portion <NUM> and the exhaust side cylinder portion <NUM> from the left side (the upper side in the vehicle mounted state). Therefore, since the insertion directions of the intake hydraulic control valve <NUM> and the exhaust hydraulic control valve <NUM> are the same as each other, the insertion work can be facilitated.

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

The chain casing <NUM> includes an intake side fastening boss portion <NUM> and an exhaust side fastening boss portion <NUM> for attaching the chain casing <NUM> to the cylinder head <NUM>. The intake side fastening boss portion <NUM> and the exhaust side fastening boss portion <NUM> are arranged below the bulging portion <NUM>.

The lower portion of the bulging portion <NUM> is connected to the upper portions of the intake side cylinder portion <NUM> and the exhaust side cylinder portion <NUM>. The upper portion of the intake side fastening boss portion <NUM> is connected to the lower portion of the intake side cylinder portion <NUM>. The upper portion of the exhaust side fastening boss portion <NUM> is connected to the lower portion of the exhaust side cylinder portion <NUM>.

The upper surface of the cylinder head <NUM> forms a joint surface joined to the cylinder head cover <NUM>. The upper surface of the cylinder head <NUM> extends in a planar shape in the front to rear direction and the left to right direction.

The intake hydraulic control valve <NUM>, the exhaust hydraulic control valve <NUM>, the intake side cylinder portion <NUM>, and the exhaust side cylinder portion <NUM> extend in parallel to the upper surface of the cylinder head <NUM>. Further, the intake hydraulic control valve <NUM>, the exhaust hydraulic control valve <NUM>, the intake side cylinder portion <NUM>, and the exhaust side cylinder portion <NUM> are arranged side by side in parallel to the upper surface of the cylinder head <NUM>.

That is, the intake hydraulic control valve <NUM>, the exhaust hydraulic control valve <NUM>, the intake side cylinder portion <NUM>, and the exhaust side cylinder portion <NUM> are arranged in the chain casing <NUM> in a posture extending in the left to right direction and in a mutual positional relationship arranged in the left to right direction.

The intake side fastening boss portion <NUM> and the exhaust side fastening boss portion <NUM> are arranged side by side in parallel to the upper surface of the cylinder head <NUM>. The intake side fastening boss portion <NUM> and the exhaust side fastening boss portion <NUM> are formed to protrude in the crank shaft direction (forward) at least from the intake side cylinder portion <NUM>.

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

Further, when the chain casing <NUM> is viewed along the crank shaft direction (see <FIG>), the exhaust side cylinder portion <NUM> is disposed to be more offset to the exhaust side (left side) than the intake side cylinder portion <NUM>. In this embodiment, the exhaust side cylinder portion <NUM> is disposed adjacent to the left side of the intake side cylinder portion <NUM>. In this way, in this embodiment, the exhaust side cylinder portion <NUM> is disposed adjacent to the front side and the left side of the intake side cylinder portion <NUM>.

In <FIG>, <FIG>, and <FIG>, the chain casing <NUM> includes a cylindrical oil passage forming portion <NUM> and the oil passage forming portion <NUM> extends in a direction orthogonal to the crank shaft direction to pass through the lower portion of the intake side fastening boss portion <NUM> and the lower portion of the exhaust side fastening boss portion <NUM>. An oil passage 27A through which the hydraulic oil flows is formed inside the oil passage forming portion <NUM>. The oil passage forming portion <NUM> is connected to the lower portion of the intake side fastening boss portion <NUM> and the lower portion of the exhaust side fastening boss portion <NUM>.

The chain casing <NUM> includes a reinforcement rib <NUM> provided below the intake side cylinder portion <NUM> and the reinforcement rib <NUM> extends in the axial direction of the intake side cylinder portion <NUM>. The reinforcement rib <NUM> connects the intake side cylinder portion <NUM>, the exhaust side cylinder portion <NUM>, and the intake side fastening boss portion <NUM>.

Specifically, the reinforcement rib <NUM> extends in the axial direction of the intake side cylinder portion <NUM> along the lower portion of the intake side cylinder portion <NUM> and the upper portion of the reinforcement rib <NUM> is connected to the lower portion of the intake side cylinder portion <NUM>. Further, the left end portion of the reinforcement rib <NUM> is connected to the lower portion of the exhaust side cylinder portion <NUM>. Then, the lower portion of the reinforcement rib <NUM> is connected to the upper portion of the intake side fastening boss portion <NUM>.

In <FIG>, <FIG>, <FIG>, and <FIG>, the chain casing <NUM> includes a boss portion <NUM> provided at the lower portion of the right end portion of the intake side cylinder portion <NUM>. The boss portion <NUM> is provided below the bulging portion <NUM>. A leg portion 15A of the intake hydraulic control valve <NUM> is fastened to the boss portion <NUM>. The leg portion 15A extends in the crank shaft direction (forward) and downward at the left end portion of the intake hydraulic control valve <NUM>.

The chain casing <NUM> includes a boss portion <NUM> provided at the upper portion of the right end portion of the exhaust side cylinder portion <NUM>. The boss portion <NUM> is provided at the bulging portion <NUM>. A leg portion 16A of the exhaust hydraulic control valve <NUM> is fastened to the boss portion <NUM>. The leg portion 16A extends in the crank shaft direction (forward) and upward at the left end portion of the exhaust hydraulic control valve <NUM>.

An intake side rib <NUM>, an exhaust side first rib <NUM>, and an exhaust side second rib <NUM> are formed on the surface of the chain casing <NUM> to protrude in the crank shaft direction (forward). A boss portion <NUM> which extends in the crank shaft direction (forward) is formed in the vicinity of the left end portion of the bulging portion <NUM> of the chain casing <NUM>. A boss portion <NUM> which extends in the crank shaft direction (forward) is formed at the upper end portion of the chain casing <NUM>.

The intake side rib <NUM> is provided in the vicinity of the right end portion of the chain casing <NUM>. The intake side rib <NUM> extends obliquely in the right down direction from the boss portion <NUM> to the right end portion below the bulging portion <NUM> of the chain casing <NUM>. The intake side rib <NUM> reinforces the boss portion <NUM> by distributing a load acting on the boss portion <NUM> toward the right end portion of the chain casing <NUM>.

The exhaust side first rib <NUM> is provided in the vicinity of the left end portion of the bulging portion <NUM> of the chain casing <NUM>. The exhaust side first rib <NUM> extends obliquely in the left up direction from the left end portion of the exhaust side cylinder portion <NUM> to the boss portion <NUM>. The exhaust side first rib <NUM> is connected to the left end portion of the exhaust side cylinder portion <NUM> and the boss portion <NUM>.

Thus, the exhaust side cylinder portion <NUM> and the boss portion <NUM> are connected by the exhaust side first rib <NUM>. Accordingly, a load acting on the exhaust side cylinder portion <NUM> is distributed to the chain casing <NUM> through the boss portion <NUM>.

The exhaust side second rib <NUM> is provided in the vicinity of the upper end portion of the chain casing <NUM>. The exhaust side second rib <NUM> extends obliquely rightward and upward from the boss portion <NUM> to the boss portion <NUM>. The exhaust side second rib <NUM> is connected to the boss portion <NUM> and the boss portion <NUM>. Thus, the boss portion <NUM> and the boss portion <NUM> are connected by the exhaust side second rib <NUM>. Accordingly, a load acting on the boss portion <NUM> is distributed to the boss portion <NUM> through the exhaust side second rib <NUM>.

As described above, in this embodiment, the chain casing <NUM> includes the cylindrical intake side cylinder portion <NUM> which bulges in the crank shaft direction and into which the intake hydraulic control valve <NUM> is inserted and the cylindrical exhaust side cylinder portion <NUM> which bulges in the crank shaft direction and into which the exhaust hydraulic control valve <NUM> is inserted. Further, the chain casing <NUM> includes the intake side fastening boss portion <NUM> and the exhaust side fastening boss portion <NUM> which are arranged below the bulging portion <NUM> and for attaching the chain casing <NUM> to the cylinder head <NUM>. Then, the lower portion of the bulging portion <NUM> is connected to the upper portions of the intake side cylinder portion <NUM> and the exhaust side cylinder portion <NUM>, the upper portion of the intake side fastening boss portion <NUM> is connected to the lower portion of the intake side cylinder portion <NUM>, and the upper portion of the exhaust side fastening boss portion <NUM> is connected to the lower portion of the exhaust side cylinder portion <NUM>.

In this way, since the lower portion of the bulging portion <NUM> is connected to the upper portions of the cylindrical intake side cylinder portion <NUM> and the exhaust side cylinder portion <NUM>, the intake side cylinder portion <NUM> and the exhaust side cylinder portion <NUM> can reinforce the bulging portion <NUM> and improve the rigidity of the bulging portion <NUM>.

Further, since the intake side cylinder portion <NUM> and the exhaust side cylinder portion <NUM> are respectively connected to the intake side fastening boss portion <NUM> and the exhaust side fastening boss portion <NUM> having high rigidity, it is possible to reinforce the lower portions of the intake side cylinder portion <NUM> and the exhaust side cylinder portion <NUM> in the chain casing <NUM>.

Accordingly, it is possible to suppress the vibration and the deformation particularly around the bulging portion <NUM> of the chain casing <NUM>. Further, since the surface rigidity of the chain casing <NUM> can be improved, it is possible to effectively block the radiated sound of the internal combustion engine <NUM>.

As a result, it is possible to suppress the vibration and the deformation of the chain casing <NUM>.

Further, in this embodiment, the intake side cylinder portion <NUM> and the exhaust side cylinder portion <NUM> are arranged side by side at different positions in the crank shaft direction.

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

Further, since the intake side cylinder portion <NUM> and the exhaust side cylinder portion <NUM> are arranged in parallel, it is possible to compactly arrange members such as the intake side cylinder portion <NUM> and the exhaust side cylinder portion <NUM> on the surface of the chain casing <NUM> and to avoid a large change in the arrangement of other members.

Further, in this embodiment, the exhaust side cylinder portion <NUM> is disposed closer to the exhaust side than the intake side cylinder portion <NUM> when the chain casing <NUM> is viewed along the crank shaft direction.

Accordingly, since the chain casing <NUM> is provided with a step in which the exhaust side cylinder portion <NUM> is disposed closer to the exhaust side than the intake side cylinder portion <NUM>, it is possible to improve the rigidity of the chain casing <NUM> and to suppress the vibration and the deformation of the chain casing <NUM>.

Further, since the intake side cylinder portion <NUM> and the exhaust side cylinder portion <NUM> are linearly arranged at the lower portion of the bulging portion <NUM>, it is possible to suppress the vibration of the bulging portion <NUM> and to improve the surface rigidity of the chain casing <NUM>. Therefore, it is possible to effectively block the radiated sound of the internal combustion engine <NUM> by the chain casing <NUM>.

Further, in this embodiment, the chain casing <NUM> includes the reinforcement rib <NUM> which is provided below the intake side cylinder portion <NUM> to extend in the axial direction of the intake side cylinder portion <NUM> and the reinforcement rib <NUM> connects the intake side cylinder portion <NUM>, the exhaust side cylinder portion <NUM>, and the intake side fastening boss portion <NUM>.

Accordingly, since the intake side cylinder portion <NUM>, the exhaust side cylinder portion <NUM>, and the intake side fastening boss portion <NUM> are connected by the reinforcement rib <NUM> below the bulging portion <NUM>, it is possible to more rigidly reinforce the lower portion of the bulging portion <NUM>. Accordingly, it is possible to suppress the vibration and the deformation in the periphery of the bulging portion <NUM> of the chain casing <NUM>.

Further, in this embodiment, the chain casing <NUM> includes the cylindrical oil passage forming portion <NUM> which extends in a direction orthogonal to the crank shaft direction to pass through the lower portion of the intake side fastening boss portion <NUM> and the lower portion of the exhaust side fastening boss portion <NUM> and the oil passage forming portion <NUM> is connected to the lower portion of the intake side fastening boss portion <NUM> and the lower portion of the exhaust side fastening boss portion <NUM>.

Accordingly, since the oil passage forming portion <NUM> having a cylindrical shape and high rigidity is connected to the lower portion of the intake side fastening boss portion <NUM> and the lower portion of the exhaust side fastening boss portion <NUM> below the bulging portion <NUM>, it is possible to reinforce a portion in the vicinity of the lower portion of the bulging portion <NUM> in the chain casing <NUM> 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 <NUM> of the chain casing <NUM>. Further, since the surface rigidity of the chain casing <NUM> is improved, it is possible to effectively block the radiated sound of the internal combustion engine <NUM> by the chain casing <NUM>.

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 are involved in the appended claims.

Claim 1:
An internal combustion engine (<NUM>) comprising:
a variable valve timing mechanism configured by winding a timing chain thereon;
intake and exhaust hydraulic control valves each controlling a hydraulic oil supplied to the variable valve timing mechanism; and
a chain casing (<NUM>) fixed to a cylinder head, to cover the timing chain and the variable valve timing mechanism,
wherein a bulging portion (<NUM>) bulging in a crank shaft direction so as to be away from the cylinder head is formed in the chain casing (<NUM>), the bulging portion (<NUM>) covering the variable valve timing mechanism,
wherein the chain casing (<NUM>) includes:
a cylindrical intake side cylinder portion (<NUM>) provided on a lower portion of the bulging portion (<NUM>) and bulging in the crank shaft direction so as to be away from the cylinder head, into which the intake hydraulic control valve is inserted;
a cylindrical exhaust side cylinder portion (<NUM>) provided on the lower portion of the bulging portion (<NUM>) and bulging in the crank shaft direction so as to be away from the cylinder head, into which the exhaust hydraulic control valve is inserted; and
intake and exhaust side fastening boss portions (<NUM>), (<NUM>) provided on respective lower portions of the intake and exhaust side cylinder portions (<NUM>), attaching the chain casing (<NUM>) to the cylinder head.