JP3799864B2 - Engine breather structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in an engine breather structure that separates oil from blow-by gas.
[0002]
[Prior art]
In an internal combustion engine in which a combustion chamber is defined by a piston, blow-by gas blown through from the combustion chamber to the valve chamber on the crank chamber or the cylinder head needs to flow out to the intake system or the engine.
[0003]
The breather structure of the engine attaches a plate to the inside of the rocker cover to define the breather chamber, separates the oil component in the process of the blow-by gas passing through the meandering passage provided in the breather chamber, and the oil component is taken away with the blow-by gas To prevent this.
[0004]
Conventionally, as this kind of breather structure, there are those disclosed in, for example, Japanese Utility Model Laid-Open No. 5-42622, Japanese Patent Application Laid-Open No. 7-18609, Japanese Patent Application Laid-Open No. 8-260934, and Japanese Patent Application Laid-Open No. 9-189212. The applicant has been filed as Japanese Patent Application No. 10-270730.
[0005]
[Problems to be solved by the invention]
However, in such a conventional breather structure of an engine, the oil accumulated in the valve chamber as the engine tilts or shakes during traveling of the vehicle flows into the breather chamber over the plate, The amount of oil carried away with blow-by gas could increase.
[0006]
In particular, in the case of an off-road vehicle or the like, in a traveling state where the inclination angle is up to 35 degrees, the engine is greatly inclined, and the engine is operated at a high speed and a large amount of oil is moved through an oil pump. Since the oil is supplied to the valve chamber, the oil accumulated in the valve chamber rises after hitting the rear wall of the valve chamber due to the shaking of the vehicle, and a large amount of oil may flow into the breather chamber . Thus, 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 large amount of oil is sucked into the intake system.
[0007]
The present invention has been made in view of the above-described problems, and an object thereof is to reduce oil consumption in an engine breather structure.
[0008]
[Means for Solving the Problems]
According to a first aspect of the present invention, a camshaft that rotates on a cylinder head, a rocker cover that defines a valve operating chamber that houses the camshaft on the cylinder head, and a blowby gas that flows out of the valve operating chamber are allowed to pass therethrough. This is applied to an engine having a breather chamber for separating oil contained in the engine.
[0009]
Then, an oil drop hole for allowing the oil in the breather chamber to flow down to the valve operating chamber is opened at the bottom of the breather chamber, the breather chamber is disposed at the rear of the valve operating chamber, and hits the rear wall of the valve operating chamber toward the breather chamber. An oil shielding plate that bounces oil is provided, and the oil shielding plate is provided downward from the bottom of the breather chamber. The oil shielding plate has a horizontal portion that extends substantially parallel to the camshaft, and a rear end that bends downward from the rear end of the horizontal portion. And a rear end portion of the oil shielding plate is opposed to a rear wall portion of the valve operating chamber with a gap .
[0010]
According to a second invention, in the first invention, an oil shielding plate comprising: 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. Were fastened together with the cam bracket via bolts.
[0011]
According to a third invention, in the first or second invention, the oil shielding plate is provided with a sealing material that contacts the rear wall portion of the valve operating chamber.
[0012]
According to a fourth aspect of the present invention, a camshaft that rotates on a cylinder head, a rocker cover that defines a valve operating chamber that houses the camshaft on the cylinder head, and a blow-by gas that flows out of the valve operating chamber are allowed to pass therethrough. In an engine equipped with a breather chamber that separates the oil contained in the engine, an oil drop hole is formed in the bottom of the breather chamber to allow the oil in the breather chamber to flow down to the valve operating chamber, and the breather chamber is disposed at the rear of the valve operating chamber. And an oil shielding plate that strikes the rear wall of the valve chamber and repels oil directed toward the breather chamber. The oil shielding plate is provided downwardly from the bottom of the breather chamber, and the oil shielding plate extends substantially parallel to the camshaft. a horizontal portion, and a rear portion bent from a rear end of the horizontal portion downward, and it shall be entered into the rear end portion of the oil blocking plate in the rear wall of the rocker cover.
[0013]
Operation and effect of the invention
In the first invention, in an operation state in which oil accumulated in the rear part of the valve operating chamber is shaken, the oil that hits the rear wall of the valve operating chamber and heads for the breather chamber is rebounded by the oil shielding plate, and the oil enters the breather chamber. Inflow can be suppressed, and the amount of oil consumed from the breather chamber to the intake passage can be reduced.
[0014]
In the second invention, the structure in which the oil shielding plate is fastened together with the cam bracket enables the oil shielding plate to be disposed to face the rear wall portion of the cylinder head directly below the breather chamber. In this case, the oil going to the breather chamber can be effectively rebounded, and the oil consumption can be reduced.
[0015]
In the third invention, the gap between the oil shielding plate and the rear wall portion of the valve operating chamber is filled with the sealing material, and the oil directed toward the breather chamber along the rear wall portion of the valve operating chamber can be rebounded without being repelled, Oil consumption can be reduced.
[0016]
In the fourth invention, the oil shielding plate is coupled to the rocker cover, and the oil shielding plate is brought into contact with the rear wall portion of the rocker cover, so that oil directed toward the breather chamber along the rear wall portion of the rocker cover is not obtained. It can be rebounded and oil consumption can be reduced.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0018]
FIG. 1 shows an overall view of an engine to which the present invention is applicable. To explain this,
The engine 1 is mounted vertically on an off-road vehicle, and is arranged so that the front end of the engine 1 faces the front of the vehicle. A left direction indicated by an arrow in FIG. 1 is the front of the vehicle and the front of the engine 1.
[0019]
In the engine 1, four cylinders 4 are provided in series on 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, 8 for each cylinder, and one fuel injection valve 9 is provided between the intake / exhaust valves 7, 8.
[0020]
Two camshafts 11 are provided side by side on the cylinder head 30 as a valve operating mechanism. The rotation of the crankshaft 10 is transmitted to each camshaft 11 via the chain 12 and the sprocket 13 and the like, and the intake and exhaust valves 7 and 8 are driven to open and close at a predetermined timing. In addition, you may provide the gear train comprised with a some gear instead of the chain 12 and the sprocket 13 grade | etc., As a power transmission mechanism. In addition, oil stored in an oil pan 15 that 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 is sucked up by an oil pump (not shown) via a strainer 16 and The oil is supplied from a pump to a valve operating mechanism such as each camshaft 11, a chain 12, a clutch shaft 10, a piston 5, etc. through an oil supply passage (not shown).
[0021]
A rocker cover 20 is attached on the cylinder head 30, and 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 perpendicular to the cylinder 4, a rear wall portion 32 rising from the rear end of the upper deck portion 31, left and right side walls (not shown) rising from the left and right ends of the upper deck portion 31, The rear wall portion 32 and the flange portion 33 continuously extending at the upper ends of the left and right side wall portions are provided, and the valve operating chamber 17 is defined by these.
[0022]
The cylinder head 30 includes a plurality of cam bearing walls 35 that support the camshafts 11, and the camshafts 11 are rotatably supported by the cam bearing walls 35 via cam brackets 36.
[0023]
A chain cover 18 is attached to the 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. 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 operating 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 for returning the oil in the valve operating chamber 17 to the oil pan 15.
[0024]
A plurality of oil drop holes (not shown) are provided in the cylinder head 30 as oil return passages in the upper deck portion 31, and oil that has lubricated the camshaft 11 and the like flows down to the upper deck portion 31, and then passes through the oil drop holes to the oil pan 15. It has come to flow down. The oil pits are formed between the cylinders 4 and at the rear end of the upper deck portion 31.
[0025]
The box-shaped rocker cover 20 includes 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. Is covered.
[0026]
The rocker cover 20 is provided with an intake duct 29 thereabove and a hood hood of a vehicle (not shown), thereby limiting the height of the ceiling wall portion 24. An oil filler cap 28 is attached to the ceiling wall portion 24 in front of the intake duct 29.
[0027]
A breather chamber 50 is provided inside the rocker cover 20. In the process of passing through the breather chamber 50, the oil contained in the blow-by gas in the valve train chamber 17 is separated. The outlet of the breather chamber 50 is communicated with an intake passage through a pipe (not shown), and blow-by gas that has passed through the breather chamber 50 is sucked into the intake passage. Note that the outlet of the breather chamber 50 may be opened to the outside of the engine 1 so that blow-by gas is discharged to the outside of the engine 1.
[0028]
The breather chamber 50 is disposed at the rear of the rocker cover 20 so as not to interfere with the intake duct 29 extending on the rocker cover 20.
[0029]
By the way, in the case of an off-road vehicle, in a traveling state where the inclination angle is up to 35 degrees, the engine 1 is greatly inclined and the engine 1 is operated at a high speed through an oil pump. A large amount of oil is supplied to the valve operating chamber 17. For this reason, the oil that does not return from the valve operating chamber 17 to the oil pan 15 gathers at the rear of the valve operating chamber 17 located below the inclination, and the oil accumulated in the lower portion of the breather chamber 50 becomes a cylinder as the vehicle shakes. There is a possibility that a large amount of oil flows into the breather chamber 50 as it rises after hitting the rear wall portion 32 of the head 30 and hits 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 arises in that a large amount of oil is sucked into the intake passage.
[0030]
In the present invention, as shown in FIG. 2, an oil shielding plate 40 extending toward the rear wall portions 22 and 32 of the valve operating chamber 17 is provided immediately below the breather chamber 50, and the breather hits the rear wall portion 32. Oil directed to the chamber 50 is rebounded by the oil shielding plate 40 to prevent the oil from flowing into the breather chamber 50.
[0031]
As shown in FIG. 3, the sheet metal oil shielding plate 40 is fastened to the cylinder head 30 via the three bolts 49 together with the cam bracket 36.
[0032]
As shown in FIGS. 4 to 6, the oil shielding plate 40 includes a horizontal portion 41 extending in a direction substantially parallel to the camshaft 11, a rear end portion 42 bent downward from the rear end of the horizontal portion 41, and a front end of the horizontal portion 41. Left and right front end portions 56 and 57 bent downward from the left and right sides, and left and right end portions 44 and 45 bent obliquely downward from the left and right ends of the horizontal portion 41.
[0033]
Three bolt holes 43 through which the bolts 49 are inserted are formed in the horizontal portion 41. A notch 46 that faces the glow plug 59 is formed at the right front end of the horizontal portion 41, and a notch 47 that faces the fuel injection valve 58 is formed between the left and right front end portions 56 and 57.
[0034]
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 and generating noise.
[0035]
Next, the operation will be described.
[0036]
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 its bottom, flows in a meandering manner by bypassing a plurality of baffle plates 61 provided in the breather chamber 50, and passes through the breather chamber 50. The oil content contained in this is separated. The blow-by gas that has passed through the breather chamber 50 is sucked out from the outlet 64 to the intake passage through 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 through the two oil drop holes 63 opened at the bottom of the breather chamber 50.
[0037]
In a traveling state in which the vehicle climbs a steep slope, the oil accumulated in the rear portion of the valve operating chamber 17 rises toward the breather chamber 50 after hitting the rear wall portion 32 of the cylinder head 30 as the vehicle shakes.
[0038]
Oil that hits the rear wall portion 32 of the cylinder head 30 and moves toward the breather chamber 50 is bounced downward by the oil shielding plate 40, and the oil is prevented from flowing into the breather chamber 50, and is sucked out from the breather chamber 50 into the intake passage. Oil consumption can be reduced.
[0039]
The oil shielding plate 40 has an L-shaped cross section due to the horizontal portion 41 and the rear end portion 42, and the oil shielding plate 40 is attached to the cam bracket 36 via the bolts 49 so as to attach the oil shielding plate 40 to the breather chamber 50. It is possible to dispose the cylinder head 30 directly against the rear wall portion 32 of the cylinder head 30, and the oil that strikes the rear wall portion 32 of the cylinder head 30 and effectively rebounds toward the breather chamber 50 can be reduced. Peeled off.
[0040]
As another embodiment, as shown in FIG. 7, a sealing material 71 is coupled to the rear end portion 42 of the oil shielding plate 40, and the sealing material 71 is brought into contact with the rear wall portion 32 of the cylinder head 30 and the plug 70. You may let them.
[0041]
In this case, the gap between the oil shielding plate 40 and the rear wall portion 32 of the cylinder head 30 is filled with the sealing material 71, and the oil heading toward the breather chamber 50 along the rear wall portion 32 of the cylinder head 30 can be rebounded. This can reduce oil consumption.
[0042]
Further, the sealing material 71 made of an elastic material does not generate noise from the contact portion with the cylinder head 30.
[0043]
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 a bolt 81.
[0044]
In this case, there is no gap between the oil shielding plate 40 and the rear wall portion 22 of the rocker cover 20, and the oil directed toward the breather chamber 50 can be bounced back along the rear wall portion 22 of the rocker cover 20. This can reduce oil consumption.
[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 showing 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 showing another embodiment.
FIG. 8 is a cross-sectional view showing still another embodiment.
[Explanation of symbols]
17 Valve operating chamber 20 Rocker cover 22 Rear wall portion 30 Cylinder head 33 Rear wall portion 36 Cam bracket 40 Oil shielding plate 49 Bolt 50 Breather chamber 71 Sealing material 80 Oil shielding plate

Claims (4)

A camshaft that rotates on the cylinder head, a rocker cover that defines a valve operating chamber that houses the camshaft on the cylinder head, and an oil contained in the blowby gas that flows out of the valve operating chamber. An engine having a breather chamber that separates a minute portion, an oil dropping hole for allowing the oil in the breather chamber to flow down to the valve operating chamber is opened at a bottom of the breather chamber, and the breather chamber is provided at a rear portion of the valve operating chamber. And an oil shielding plate that hits a rear wall portion of the valve operating chamber and repels oil directed toward the breather chamber, the oil shielding plate being provided downwardly from the bottom of the breather chamber, wherein the oil shielding plate is disposed on the cam A horizontal portion extending substantially parallel to the shaft; and a rear end portion bent downward from a rear end of the horizontal portion; and the rear end portion of the oil shielding plate is connected to the valve chamber. Breather structure for an engine, characterized in that is opposed with a gap to the rear wall.   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. The engine breather structure according to claim 1, wherein the breather structure is fastened to the cylinder head.   The engine breather structure according to claim 1, wherein the oil shielding plate is provided with a sealing material that abuts against a rear wall portion of the valve operating chamber. A camshaft that rotates on the cylinder head, a rocker cover that defines a valve operating chamber that houses the camshaft on the cylinder head, and an oil contained in the blowby gas that flows out of the valve operating chamber. An engine having a breather chamber that separates a minute portion, an oil dropping hole for allowing the oil in the breather chamber to flow down to the valve operating chamber is opened at a bottom of the breather chamber, and the breather chamber is provided at a rear portion of the valve operating chamber. And an oil shielding plate that hits a rear wall portion of the valve operating chamber and repels oil directed toward the breather chamber, and is provided to be separated downward from a bottom portion of the breather chamber, and the oil shielding plate is disposed on the cam. has a horizontal portion extending parallel shaft and substantially, a rear end portion bent downward from the rear end of the horizontal portion, the rocker rear end portion of the oil blocking plate Breather structure features and to Rue engine that has been fastened to the rear wall portion of the bar.

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