WO2014034050A1 - Breather structure for engine - Google Patents

Description

Engine breather structure

The present invention relates to a breather structure provided on a cylinder head cover of an engine.

Generally, a breather chamber for separating and removing oil mist from blow-by gas circulating to the intake system is provided inside the ceiling wall of the cylinder head cover of the engine. For example, in Patent Document 1, when the breather chamber is formed by the cylinder head cover and the baffle plate, the baffle plate is formed in a dish shape, and the engagement hook at the upper end of the side wall is engaged with the locking rib of the cylinder head cover. Is described. In Patent Document 1, a fitting projection is formed on the upper end surface of the side wall of the baffle plate, and the fitting projection is fitted into the fitting recess of the cylinder head cover so that the cylinder head cover and the baffle plate are in close contact with each other. It is also described.

Patent Document 2 describes that a wall forming a breather chamber protrudes downward from a cylinder head cover, and a baffle plate is screwed to the lower end of the wall. Patent Document 2 also describes that a ridge having a sharp tip is provided at the lower end of the wall, and the cusp of the ridge is compressed and deformed to be brought into airtight contact with the baffle plate.

Japanese Utility Model Publication No. 5-64444 Japanese Utility Model Publication No. 56-161160

According to the breather structure of Patent Document 1, it is possible to easily attach the baffle plate to the cylinder head cover. However, in the fitting between the fitting convex portion and the fitting concave portion for obtaining airtightness, when the dimensional accuracy of the cylinder head cover and the baffle plate is low, the closeness of the fitting portion is lowered and airtightness is ensured. Difficult to do. Even in the breather structure of Patent Document 2, high dimensional accuracy is required for the cylinder head cover and the baffle plate, or for the shape of the tip of the ridge to reliably compress and deform the tip of the ridge over the entire circumference of the baffle plate. It is difficult to ensure airtightness.

Therefore, the present invention makes it possible to easily increase the airtightness between the breather plate (corresponding to the baffle plate) and the cylinder head cover without requiring high component dimensional accuracy.

In the present invention, in order to solve the above problems, oil separated from blow-by gas is used for improving the airtightness.

In the engine breather structure presented here, a breather chamber for blow-by gas is formed between the cylinder head cover of the engine and a breather plate disposed below the cover. That is, a column that supports the breather plate in a suspended state and a main body wall that forms the outer wall of the breather chamber protrude downward from the ceiling wall of the cylinder head cover. The plate is fitted into a concave groove for body wall in which oil separated from the blow-by gas is accumulated.

Therefore, according to the breather structure, even if there is a gap in the fitting portion between the lower end of the body wall of the cylinder head cover and the groove of the breather plate, the gap is blocked by the oil accumulated in the groove. High airtightness can be obtained. That is, since the oil increases the airtightness, the cylinder head cover and the breather plate do not require high dimensional accuracy.

In a preferred aspect of the present invention, the breather chamber is provided with a plurality of partition walls protruding downward from the ceiling wall of the cylinder head cover. The plurality of partition walls form a blow-by gas passage that is zigzag-folded in the breather chamber. A lower end portion of each of the plurality of partition walls is fitted in a groove for partition wall formed in the breather plate and storing oil separated from the blow-by gas. The groove for the main body wall and the groove for the partition wall are continuous with each other.

Therefore, the blowby gas of the engine collides with the main body wall and the partition wall when passing through the zigzag blowby gas passage. Due to this collision, the oil mist mixed in the blow-by gas adheres to the main body wall and the partition wall, is separated from the blow-by gas, and falls along the main body wall and the partition wall. As a result, oil accumulates in the main body wall groove and the partition wall groove in which the lower ends of the main body wall and the partition wall are fitted.

In a preferred embodiment of the present invention, the lower end portion of the main body wall is formed in a tapered shape. Alternatively, the lower end of each of the main body wall and the partition wall is formed in a tapered shape. This facilitates the assembly of the breather plate to the cylinder head cover.

In a preferred aspect of the present invention, the cylinder head cover and the breather plate are both made of synthetic resin, and the support column is ultrasonically welded to the lower surface of the breather plate at the tip protruding downward through the breather plate. . That is, for fixing the breather plate to the cylinder head cover, it is possible to employ screwing or vibration welding as in Patent Document 2, but with screwing, the number of parts increases, and vibration welding that welds the wall and the plate is performed. Then, welding dust remains in the breather chamber, and the equipment cost increases. In this respect, according to the above ultrasonic welding, since a part is welded from the outside, the breather plate is securely attached to the cylinder head cover without increasing the number of parts, increasing the equipment cost, and generating dust in the breather chamber. Can be fixed to.

In a preferred aspect of the present invention, the support column is formed such that the lower end portion has a stepped portion with a smaller diameter than the upper portion thereof, the lower end portion having the smaller diameter penetrates the breather plate, and the stepped portion is It is in contact with the upper surface of the breather plate. Accordingly, the breather plate is positioned with respect to the cylinder head cover when the stepped portion of the column performs ultrasonic welding, and the welding work is facilitated.

According to the present invention, the lower end portion of the main body wall that protrudes from the cylinder head cover and forms the wall of the breather chamber is fitted into the concave groove for the main body wall in which the oil formed in the breather plate is accumulated. The air tightness of the breather chamber can be increased by the oil accumulated in the groove without requiring high dimensional accuracy in the breather plate, which is advantageous for separating oil mist from blow-by gas.

It is sectional drawing which shows the breather structure of an engine. It is a bottom view of the structure. It is a perspective view of the breather plate of the same structure. It is an expanded sectional view of the A part of FIG. It is an expanded sectional view of the B section of FIG. It is explanatory drawing corresponding to FIG. 4 which shows the state which the oil collected in the fitting part.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its application, or its use.

In FIG. 1, 1 is a synthetic resin cylinder head cover that covers a cylinder head of a motorcycle engine, and 2 is a synthetic resin breather plate that forms a breather chamber 3 together with the cylinder head cover 1.

The cylinder head cover 1 includes a plurality of support columns 4 that support the breather plate 2 in a suspended state, a body wall 5 that forms the outer wall of the breather chamber 3, a plurality of partition walls 6 that form a blow-by gas passage in the breather chamber 3, And a gas outlet pipe 7. The column 4, the main body wall 5, and the partition wall 6 protrude downward from the ceiling wall of the cylinder head cover 1. The gas outlet pipe 7 protrudes laterally from the side wall of the cylinder head cover 1. The gas outlet pipe 7 is connected to a breather pipe for returning the blow-by gas from the breather chamber 3 to the intake system. The breather plate 2 is provided with a main body wall concave groove 8 and a plurality of partition wall concave grooves 9 which are opened upward to fit the lower ends of the main body wall 5 and the partition wall 6 of the cylinder head cover 1.

As shown in FIG. 2 (bottom view of breather structure), the main body wall 5 of the cylinder head cover 1 is disposed in a substantially rectangular shape. On the side opposite to the gas outlet pipe 7, the main body wall 5 is provided with end walls extending from both sides in a staggered manner, and a space between the end walls serves as a blow-by gas inlet 11 for the breather chamber 3. The partition walls 6 protrude alternately from the main body walls 5 on both sides toward the gas outlet pipe 7 from the inlet 11. As a result, a blow-by gas passage folded back in a zigzag manner is formed in the breather chamber 3.

As shown in FIG. 3, the breather plate 2 has a body wall groove 8 and a partition wall groove 9 formed at a heightened level on the upper surface of the plate. The groove 8 for the main body wall is provided in a substantially rectangular shape along the peripheral edge of the breather plate 2 so as to correspond to the main body wall 5 of the cylinder head cover 1 and extends from both sides on the opposite side to the gas outlet pipe 7. Is going wrong. The partition wall groove 9 protrudes alternately from the body wall groove 8 on both sides to the center of the breather plate 2 corresponding to the partition wall 6 of the cylinder head cover 1. The main body wall concave groove 8 and the partition wall concave groove 9 are continuous with each other. Further, the breather plate 2 is provided with a plurality of through holes 12 through which the lower end portion of the column 4 of the cylinder head cover 1 passes.

As shown in FIG. 4, the lower end 5a of the main body wall 5 of the cylinder head cover 1 is formed in a tapered shape. Although this illustration is omitted, the partition wall 6 is also the same, and its lower end is formed in a tapered shape. Thus, the tapered lower ends of the main body wall 5 and the partition wall 6 are fitted into the main body wall groove 8 and the partition wall groove 9 of the breather plate 2.

The column 4 of the cylinder head cover 1 has a cylindrical shape, and as shown in an enlarged view in FIG. 5, the lower end portion 13 has a stepped portion 14 and a smaller diameter than the upper portion thereof. The lower end portion 13 having the small diameter penetrates the through hole 12 of the breather plate 2, and the stepped portion 14 is in contact with the upper surface of the breather plate 2. Thus, the tip 13a that protrudes downward through the through hole 12 of the support column 4 is deformed and welded to the lower surface of the breather plate 2 (ultrasonic welding). That is, the tip 13 a of the support column 4 is melted and deformed by ultrasonic vibration and pressure and is welded to the lower surface of the breather plate 2.

According to the breather structure as described above, the blow-by gas of the engine flows into the breather chamber 3 by the intake negative pressure from the inlet 11 between the end walls where the main body wall 5 is misplaced, and the blow-by gas passage becomes zigzag. When passing through, the main body wall 5 and the partition wall 6 collide. Due to this collision, the oil mist mixed in the blow-by gas adheres to the main body wall 5 and the partition wall 6 and is separated from the blow-by gas, and falls along the main body wall 5 and the partition wall 6. As a result, oil accumulates in the main body wall groove 8 and the partition wall groove 9 in which the lower ends of the main body wall 5 and the partition wall 6 are fitted.

The blow-by gas from which the oil mist has been separated and removed returns to the engine intake system through the breather pipe from the gas outlet pipe 7. A part of the oil separated from the blowby gas is accumulated in the main body wall concave groove 8 and the partition wall concave groove 9, and the rest is discharged downward from the outlet 11 through the bottom surface of the breather chamber 3.

As shown in FIG. 6, in the fitting portion between the lower end portion 5 a of the main body wall 5 and the main body wall groove 8, the oil 15 accumulated in the main body wall groove 8 serves as a seal that closes the gap between the fitting portions. Fulfill. That is, blow-by gas containing oil mist enters the breather chamber 3 from the fitting portion between the main body wall 5 and the main body wall concave groove 8 by the oil 15 accumulated in the main body wall concave groove 8. Therefore, the return of the blow-by gas having a large oil content to the intake system is prevented.

Further, according to the breather structure, since the lower end portions of the main body wall 5 and the partition wall 6 are formed in a tapered shape, the assembly of the breather plate 2 to the cylinder head cover 1 is facilitated. In addition, since the lower end portion of the column 4 of the cylinder head cover 1 is ultrasonically welded to the lower surface of the breather plate 2 through the through hole 12 of the breather plate 2, the number of parts is increased, the equipment cost is increased, and welding is performed in the breather chamber. The breather plate 2 can be securely fixed to the cylinder head cover 1 without causing the generation of dust. In particular, in the above embodiment, the stepped portion 14 provided on the support column 4 is brought into contact with the upper surface of the breather plate 2 to perform ultrasonic welding. Therefore, since the step portion 14 positions the breather plate 2 with respect to the cylinder head cover 1 when performing ultrasonic welding, the welding work is facilitated.

In the above embodiment, the lower end portions of the main body wall 5 and the partition wall 6 of the cylinder head cover 1 are formed in a tapered shape. However, the width of the main body wall concave groove 8 and the partition wall concave groove 9 increases toward the bottom. You may make it the taper-shaped groove shape which became narrow.

Further, the fixing of the breather plate 2 to the column 4 of the cylinder head cover 1 is not limited to ultrasonic welding, and other means such as screwing or vibration welding may be employed.

Further, the present invention can be applied not only to motorcycle engines but also to other engines such as automobiles and agricultural machines.

DESCRIPTION OF SYMBOLS 1 Cylinder head cover 2 Breather plate 3 Breather chamber 4 Strut 5 Body wall 6 Partition wall 7 Gas outlet pipe 8 Groove for main body wall 9 Groove for partition wall 11 Inlet 12 Through-hole 13 Lower end part 13a Tip weld part 14 Step part 15 Oil

Claims (6)

A breather structure for an engine in which a breather chamber for blow-by gas is formed between an engine cylinder head cover and a breather plate disposed below the cylinder head cover.
From the ceiling wall of the cylinder head cover, a support column that supports the breather plate in a suspended state and a main body wall that forms the outer wall of the breather chamber protrude downward.
A breather structure for an engine, wherein a lower end portion of the main body wall is fitted in a main wall recess formed in the breather plate, in which oil separated from the blow-by gas is accumulated. In claim 1,
The breather chamber is provided with a plurality of partition walls projecting downward from the ceiling wall of the cylinder head cover, and the plurality of partition walls form a blow-by gas passage that is zigzag folded into the breather chamber.
A lower end portion of each of the plurality of partition walls is fitted in a groove for partition wall formed in the breather plate and storing oil separated from the blow-by gas,
A breather structure for an engine, wherein the groove for main body wall and the groove for partition wall are continuous with each other. In claim 1,
A breather structure for an engine, wherein a lower end portion of the main body wall is formed in a tapered shape. In claim 2,
A breather structure for an engine, wherein a lower end portion of each of the main body wall and the partition wall is formed in a tapered shape. In any one of Claims 1 thru | or 4,
Both the cylinder head cover and breather plate are made of synthetic resin.
A breather structure for an engine, wherein a tip of the support column is ultrasonically welded to a lower surface of the breather plate so as to protrude downward through the breather plate. In claim 5,
The column has a lower end portion with a stepped portion smaller than its upper portion, and the lower end portion having the smaller diameter passes through the breather plate, and the stepped portion contacts the upper surface of the breather plate. The breather structure of the engine is characterized by contact.

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