JP2000265820A - Breather structure for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an oil consumption rate in a breather structure of an engine in which oil is easily struck against a breather chamber. SOLUTION: In an engine, a rocker cover 20 defines a valve system chamber 17 housing a valve system on a cylinder head and blowby gass flowing out from the valve system chamber 17 is passed through the breather chamber 50 in which oil content therein is saparated from the blowby gas. In the engine, the breather chamber 50 is arranged on a rear side of the valve system chamber 17. In addition, an oil shielding plate 40 is arranged for repelling the oil which is struck against a rear wall part 32 of the valve system chamber 17 and directed to the breather chamber 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved breather structure of an engine for separating oil from blow-by gas.

[0002]

2. Description of the Related Art In an internal combustion engine in which a combustion chamber is defined by a piston, blow-by gas blown from the combustion chamber into a crank chamber or a valve operating chamber on a cylinder head needs to flow out to an intake system or the outside of the engine. .

[0003] The breather structure of the engine is such that a plate is attached to the inside of a rocker cover to define a breather chamber, and the blow-by gas separates an oil component while passing through a meandering passage provided in the breather chamber. Is prevented from being taken away.

Conventionally, as a breather structure of this kind, for example, Japanese Utility Model Laid-Open No. 5-42222 and Japanese Patent Laid-Open No. 7-18609.
JP, JP-A-8-260934, JP-A-9-1
Japanese Patent Application Laid-Open No. 89212/89, and an application filed by the present applicant as Japanese Patent Application No. 10-270730.

[0005]

However, in such a conventional breather structure of an engine, oil accumulated in a valve operating chamber as the engine is tilted or shakes when the vehicle is running or the like is a plate. And the amount of oil flowing into the breather chamber and being taken away with the blow-by gas may increase.

In particular, in the case of an off-road vehicle or the like, when the vehicle is running up a hill where the inclination angle reaches 35 degrees, the engine is greatly inclined, and the engine is operated at a high revolution and a large amount of oil is passed through an oil pump. Since oil is supplied to the valve operating chamber, the oil accumulated in the valve operating chamber may rise after hitting the rear wall of the valve operating chamber due to the sway of the vehicle, and a large amount of oil may flow into the breather chamber. There is. When the oil that has flowed into the breather chamber reaches the blow-by gas outlet of the breather chamber that communicates with the intake system, a problem occurs in that a large amount of oil is sucked into the intake system.

[0007] The present invention has been made in view of the above problems, and has as its object to reduce oil consumption in a breather structure of an engine.

[0008]

According to a first aspect of the present invention, there is provided a rocker cover defining a valve operating chamber for accommodating a valve operating mechanism on a cylinder head, and a blow-by gas flowing out of the valve operating chamber passing therethrough. The present invention is applied to an engine having a breather chamber for separating an oil component contained in the engine.

The breather chamber is disposed at the rear of the valve operating chamber, and has an oil shielding plate that hits the rear wall of the valve operating chamber and bounces off the oil toward the breather chamber.

According to a second aspect of the present invention, in the first aspect, there is provided a camshaft rotating on the cylinder head, a cam bracket for rotatably supporting the camshaft, and a bolt for fastening the cam bracket to the cylinder head, The oil shielding plate was fastened together with the cam bracket via bolts.

According to a third aspect of the present invention, in the first or second aspect, the oil shielding plate is provided with a sealing material which is in contact with the rear wall of the valve operating chamber.

In a fourth aspect based on the first aspect, the oil shielding plate is connected to the rocker cover, and the oil shielding plate is brought into contact with the rear wall of the rocker cover.

[0013]

According to the first aspect of the present invention, in the operation state in which the oil accumulated in the rear part of the valve operating chamber fluctuates, the oil that hits the rear wall part of the valve operating chamber toward the breather chamber is rebounded by the oil shielding plate. As a result, the flow of oil into the breather chamber is suppressed, and the amount of oil drawn from the breather chamber into the intake passage can be reduced.

According to the second aspect of the present invention, the structure in which the oil shielding plate is fastened together with the cam bracket makes it possible to dispose the oil shielding plate directly below the breather chamber so as to face the rear wall of the cylinder head. The oil hitting the rear wall and heading toward the breather chamber can be effectively bounced back, and the oil consumption can be reduced.

In the third aspect of the invention, the gap between the oil shielding plate and the rear wall of the valve operating chamber is filled with the sealing material, and the oil is repelled along the rear wall of the valve operating chamber toward the breather chamber without being returned. Oil consumption can be reduced.

In the fourth aspect of the present invention, the oil shielding plate is connected to the rocker cover and the oil shielding plate is brought into contact with the rear wall of the rocker cover, so that the oil flowing toward the breather chamber along the rear wall of the rocker cover. Can be bounced off without getting any oil, and the oil consumption can be reduced.

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an overall view of an engine to which the present invention can be applied. Explaining this, the engine 1 is mounted vertically on an off-road vehicle, and is arranged such that the front end of the engine 1 faces forward of the vehicle. In FIG. 1, the left direction indicated by an arrow is the front of the vehicle and the front of the engine 1.

In the engine 1, four cylinders 4 are provided in series in a cylinder block 2, and a combustion chamber 6 is defined between each piston 5 and a cylinder head 30. The cylinder head 30 is provided with two intake / exhaust valves 7 and 8 for each cylinder, and one fuel injection valve 9 is provided between the intake / exhaust valves 7 and 8.

Two camshafts 11 are provided side by side on a cylinder head 30 as a valve operating mechanism. Each camshaft 11 has a rotation of the crack shaft 10 and a chain 12.
And via the sprocket 13 and the like, and drives the intake and exhaust valves 7, 8 to open and close at a predetermined timing. The chain 12 and the sprocket 13 serve as a power transmission mechanism.
Alternatively, a gear train including a plurality of gears may be provided. The oil stored in the oil pan 15 may be provided with a timing belt and a timing pulley instead of the chain 12 and the sprocket 13 as a power transmission mechanism. The oil is supplied from a pump to a valve operating mechanism such as each camshaft 11, a chain 12, a crack shaft 10, a piston 5 and the like through an oil supply passage (not shown).

The rocker cover 2 is mounted on the cylinder head 30.
A valve operating chamber 17 for accommodating a valve operating mechanism such as each camshaft 11 is defined therebetween. The cylinder head 3 includes an upper deck portion 31 extending in a horizontal direction substantially orthogonal to the cylinder 4, a rear wall portion 32 rising from a rear end of the upper deck portion 31, left and right side wall portions (not shown) rising from right and left ends of the upper deck portion 31, Rear wall 32
And a flange portion 33 extending continuously at the upper end of the left and right side wall portions, thereby defining the valve operating chamber 17.

The cylinder head 30 is mounted on each camshaft 11
The camshaft 11 is rotatably supported by a cam bracket 36 on each cam bearing wall 35.

A chain cover 18 is attached to a front portion of the cylinder head 30 via a gear case 39, and a power transmission chamber 19 for accommodating a power transmission mechanism such as the chain 12 and the sprocket 13 is defined therebetween. You. The front wall portion 34 of the cylinder head 30 extends downward from the front end of the upper deck portion 31, and the oil in the valve chamber 17 flows down the front wall portion 34 and returns to the oil pan 15. Therefore, the power transmission chamber 19 functions as an oil return passage that returns the oil in the valve train chamber 17 to the oil pan 15.

A plurality of oil drop holes (not shown) are opened in the cylinder head 30 as an oil return passage in the upper deck portion 31. After oil lubricating the camshaft 11 and the like flows down to the upper deck portion 31, the oil passes through each oil drop hole. It flows down to the pan 15.
The oil drop holes are formed between the cylinders 4 and at the rear end of the upper deck 31.

The box-shaped rocker cover 20 has front and rear wall portions 21 and 22, left and right side wall portions 23, a ceiling wall portion 24, a flange portion 25 for the cylinder head 30, and the like. The upper part of 17 is covered.

The rocker cover 20 is provided with an intake duct 29 above and a hood (not shown) of a vehicle, which limits the height of the ceiling wall 24. An oil filler cap 28 is attached to the ceiling wall 24 in front of the intake duct 29.

Inside the rocker cover 20, a breather chamber 5 is provided.
0 is provided. As the blow-by gas in the valve operating chamber 17 passes through the breather chamber 50, oil contained therein is separated. The outlet of the breather chamber 50 communicates with the intake passage via a pipe (not shown), and the blow-by gas that has passed through the breather chamber 50 is sucked into the intake passage. The outlet of the breather chamber 50 may be opened to the outside of the engine 1 to discharge the blow-by gas to the outside of the engine 1.

The breather chamber 50 is disposed at the rear of the rocker cover 20 and extends on the rocker cover 20.
9 does not interfere.

By the way, in the case of an off-road vehicle, in a running state in which the vehicle goes up a slope having an inclination angle of 35 degrees,
A large amount of oil is supplied to the valve train chamber 17 via an oil pump as the engine 1 is largely inclined and the engine 1 is operated at a high speed. For this reason, the oil that cannot return from the valve operating chamber 17 to the oil pan 15 collects at the rear part of the valve operating chamber 17 located below the slope, and the oil that has accumulated under the breather chamber 50 is released by the cylinder with the vibration of the vehicle. There is a possibility that a large amount of oil flows into the breather chamber 50 by rising after hitting the rear wall 32 of the head 30 and hitting the bottom of the breather chamber 50. When the oil that has flowed into the breather chamber 50 reaches the outlet of the breather chamber 50, a problem occurs in which a large amount of oil is sucked into the intake passage.

The present invention addresses this problem, as shown in FIG. 2, just below the breather chamber 50, the rear wall 22,
And an oil shielding plate 40 extending toward the rear wall portion 3.
The oil which goes to the breather chamber 50 in step 2 is repelled by the oil shielding plate 40 to suppress the oil from flowing into the breather chamber 50.

As shown in FIG. 3, the oil shielding plate 40 made of sheet metal is fastened to the cylinder head 30 together with the cam bracket 36 via three bolts 49.

As shown in FIGS. 4 to 6, the oil shielding plate 4
0 is a horizontal portion 41 extending in a direction substantially parallel to the camshaft 11.
And a rear end portion 42 bent downward from the rear end of the horizontal portion 41.
And left and right front ends 56 and 57 bent downward from the front end of the horizontal portion 41, and left and right ends 44 and 45 bent obliquely downward from the left and right ends of the horizontal portion 41.

The horizontal portion 41 is formed with three bolt holes 43 through which the bolts 49 are inserted. A cutout 46 facing the glow plug 59 is formed at the right front end of the horizontal portion 41, and a cutout 47 facing the fuel injection valve 58 is formed between the left and right front ends 56 and 57.

The rear end portion 42 of the oil shielding plate 40 faces the rear wall portion 32 of the cylinder head 30 and the rear wall portion 22 of the rocker cover 20 with a small gap, and prevents them from hitting each other to generate noise.

The operation as described above will now be described.

The blow-by gas in the valve operating chamber 17 flows into the breather chamber 50 from the blow-by gas intake port 62.
The blow-by gas in the blow-by gas introduction passage 60 flows into the breather chamber 50 from the bottom thereof, flows meandering by bypassing a plurality of baffles 61 provided in the breather chamber 50, and flows through the breather chamber 50. The oil contained therein is separated. The blow-by gas that has passed through the breather chamber 50 is sucked from the outlet 64 to an intake passage via a pipe (not shown). The oil separated from the blow-by gas in the breather chamber 50 flows down to the valve operating chamber 17 from two small oil drop holes 63 opened at the bottom of the breather chamber 50.

In a running state in which the vehicle climbs a steep hill, oil accumulated in the rear portion of the valve operating chamber 17 hits the rear wall portion 32 of the cylinder head 30 as the vehicle shakes and then rises toward the breather chamber 50. I do.

The oil that hits the rear wall 32 of the cylinder head 30 and travels toward the breather chamber 50 is bounced downward by the oil shielding plate 40, and the oil is repelled by the breather chamber 5.
0 is suppressed, and the amount of oil consumed from the breather chamber 50 into the intake passage can be reduced.

The oil shielding plate 40 has an L-shaped cross section by its horizontal portion 41 and rear end portion 42. The oil shielding plate 40 is fastened and mounted on the cam bracket 36 through bolts 49, so that the oil shielding plate 40 is breathed. The cylinder head 30 can be disposed immediately below the chamber 50 so as to face the rear wall 32 of the cylinder head 30, so that the oil that hits the rear wall 32 of the cylinder head 30 and travels toward the breather chamber 50 can be effectively bounced off. Is reduced.

As another embodiment, as shown in FIG. 7, a sealing member 71 is connected to the rear end portion 42 of the oil shielding plate 40, and the sealing member 71 is attached to the rear wall portion 32 of the cylinder head 30.
And the stopper 70.

In this case, the gap between the oil shielding plate 40 and the rear wall 32 of the cylinder head 30 is filled with the sealing material 71, so that no oil is directed toward the breather chamber 50 along the rear wall 32 of the cylinder head 30. It can bounce off and reduce oil consumption.

Further, the sealing material 71 made of an elastic material does not generate noise from the contact portion with the cylinder head 30.

As another embodiment, as shown in FIG. 8, an oil shielding plate 80 having an L-shaped cross section may be fastened to the rear wall portion 22 of the rocker cover 20 via bolts 81.

In this case, there is no gap between the oil shielding plate 40 and the rear wall portion 22 of the rocker cover 20.
The breather chamber 50 extends along the rear wall 22 of the rocker cover 20.
The oil can be bounced back without receiving the oil toward the, and the oil consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an engine showing an application example of the present invention.

FIG. 2 is a cross-sectional view illustrating an embodiment of the present invention.

FIG. 3 is an exploded perspective view of the same.

FIG. 4 is a side view of the oil shielding plate.

FIG. 5 is a plan view of the oil shielding plate.

FIG. 6 is a front view of the oil shielding plate.

FIG. 7 is a cross-sectional view illustrating another embodiment.

FIG. 8 is a sectional view showing still another embodiment.

[Explanation of symbols]

 17 Valve operating chamber 20 Rocker cover 22 Rear wall 30 Cylinder head 33 Rear wall 36 Cam bracket 40 Oil shielding plate 49 Bolt 50 Breather chamber 71 Seal material 80 Oil shielding plate

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tamotsu Yamatani F-term in Nissan Diesel Industry Co., Ltd., 1st place, Dai-Chome, Ageo-shi, Saitama (Reference) 3G015 BD10 BD25 BE06 BE14 BF03 BF04 BF05 BF07 BF08 CA05 DA07

Claims (4)

[Claims] 1. A rocker cover defining a valve operating chamber for accommodating a valve operating mechanism on a cylinder head, and a breather for passing a blow-by gas flowing out of the valve operating chamber to separate an oil component contained therein. And an oil shield plate that arranges the breather chamber at a rear portion of the valve operating chamber and that bounces oil directed toward the breather chamber against a rear wall of the valve operating chamber. Engine breather structure. 2. A camshaft that rotates on the cylinder head, a cam bracket that rotatably supports the camshaft, and a bolt that fastens the cam bracket to the cylinder head. 2. The breather structure for an engine according to claim 1, wherein the engine is fastened to the cylinder head together with the cam bracket. 3. A breather structure for an engine according to claim 1, wherein said oil shielding plate is provided with a seal member which is in contact with a rear wall portion of said valve operating chamber. 4. The breather structure for an engine according to claim 1, wherein said oil shielding plate is connected to said rocker cover, and said oil shielding plate is abutted against a rear wall of said rocker cover.