JPH0231531Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field of the Invention) This invention relates to a breather (ventilation) device installed in a four-stroke V-type internal combustion engine for a motorcycle.

(Technical background) As is well known, in the crankcase of a four-stroke internal combustion engine, there are changes in the internal pressure of the crankcase due to the vertical movement of the piston, an increase in the internal pressure of the crankcase due to blow-by gas leaking from the combustion chamber, and an increase in oil due to moisture in the blow-by gas. A breather device is installed to prevent dilution, etc.

(Prior Art and Problems) Conventionally, such a breather device has a structure in which the breather chamber is provided only in the crankcase, as shown in, for example, Japanese Utility Model Application Publication No. 59-81865. Therefore, the length of the breather chamber (the length in the direction in which exhaust gas flows) cannot be made long due to installation space issues, and is kept relatively short.

By the way, when the internal combustion engine is running, the upper part of the crankcase (near where the breather device is installed) is filled with oil droplets, so when exhaust gas flows into the breather device, Oil droplets will be mixed in. For this reason, the breather device must have the function of separating oil droplets mixed in when exhaust gas passes through. Oil droplets mixed in the exhaust gas are separated when the exhaust gas flows into the breather chamber and collides with the chamber wall as it flows toward the atmosphere. Also, the separated oil flows back into the crankcase.

However, in the case of the conventional structure, the length of the breather chamber that effectively separates the oil droplets from the exhaust gas is short, so the oil droplet separation effect is low, and as a result, some of the oil droplets are not separated and remain mixed in the exhaust gas. It is also released into the atmosphere.

To deal with this problem, the length of the breather chamber can be set large, but the installation space is limited within the crankcase due to the arrangement of elements (for example, transmission gears, etc.) installed in that part. On the other hand,
Protruding outward from the crankcase caused the problem of increasing the size of the crankcase, which was not a desirable solution.

It has been particularly difficult to solve the above problem in V-type internal combustion engines for motorcycles, which have large installation space restrictions.

(Purpose of the invention) Therefore, in view of the above-mentioned circumstances, this invention is not affected by installation space constraints due to the arrangement of elements installed in the crankcase, and is designed to increase the size of the crankcase. To provide a breather device for a V-type internal combustion engine for a motorcycle, which can obtain a breather chamber with a large chamber length and improve the effect of separating exhaust gas and oil.

(Structure of the invention) In order to achieve the above object, this invention provides a breather device for an internal combustion engine of a motorcycle, which includes a first breather chamber provided in the cylinder head of the internal combustion engine and a second breather chamber provided in the crankcase. (a) the internal combustion engine is a V-type internal combustion engine; ) The second breather chamber is provided in the upper part of the crankcase above the transmission chamber in communication with the first breather chamber, and (d) The axis of the first breather chamber is relative to the axis of the second breather chamber. (e) The second breather chamber has a shape in which the volume gradually increases from the inlet side to the outlet side. A breather device for an internal combustion engine of a motorcycle is provided.

(Embodiment of the invention) An embodiment of the invention will be described below with reference to FIGS. 1 and 2.

Figure 1 is a longitudinal sectional view of the part where the gear train that transmits the rotational power of the crankshaft of a V-type internal combustion engine of a motorcycle to the camshaft is located, and Figure 2 is an enlarged view of the main part of Figure 1. .

In the figure, 1 is a crankcase, 2 is a cylinder head, 3 is a cylinder head cover, 4 is a crankshaft, 5 is a camshaft, 6 is an idle gear 8 that meshes with the drive gear 7 of the crankshaft 4, and the idle gear 8. A gear train consisting of an idle gear 9 that meshes with the idle gear 9 and a driven gear 10 mounted on the camshaft 5 that meshes with the idle gear 9, 11 and 12 are transmission gears, and 13 is installed in a portion of the crankcase 1 above the transmission gears 11 and 12. It is a breather device.

The breather device 13 has a breather chamber 14 thereof.
is composed of an upper breather chamber (first breather chamber) 15 formed in the lower part of the cylinder head 2 and a lower breather chamber (second breather chamber) 16 formed in the upper part of the crankcase 1. has been done.

In the illustrated case, the upper breather chamber 15 is formed by making the upper breather chamber forming portion of the side wall 2a on the bank side opposite to the left side of the cylinder head 2 of the cylinder on the right bank thick in FIG. 1 (a boss 2b is provided). It is formed by twisting. Further, the lower breather chamber 16 is formed by the top wall 16a by the side wall 1a of the crankcase 1.
A vertical wall provided integrally with the top wall 16a constitutes a circumferential wall 16b, and the circumferential wall 16
The bottom wall 16c is constituted by a metal plate that is bonded (adhered) to the lower end of the bottom wall 16b via a bonding member 17.
The upper breather chamber 15 and the lower breather chamber 16 are communicated with each other via a communication chamber 16d provided in the lower breather chamber 16. The upper breather chamber 15 is arranged so that its axis is at an angle with respect to the axis of the lower breather chamber 16, and in the illustrated example, it is at a substantially right angle. As a result, a curved exhaust gas passage passing through the upper and lower breather chambers 15, 16 is formed. In addition, the lower breather chamber 16 has a top wall 16
It is divided into two chambers by a partition wall 16e constituted by a vertical wall provided integrally with a, and has a first chamber 16f and a second chamber 16g. The first chamber 16f and the second chamber 16g communicate with each other via a notch 16h formed at the lower end of the partition wall 16e. 1st room 16f
is the partition wall 1 from the inlet (gas introduction hole 19 described later) side.
While the second chamber 16g has a substantially triangular cross section with a height gradually increasing toward the 6e side, the second chamber 16g has a greater height than the first chamber 16f, and therefore the lower breather chamber 16 as a whole is connected from the gas introduction hole 19 to the communication chamber. It has a structure in which the volume gradually increases toward 16d.

The upper breather chamber 15 has an outlet pipe 18 that communicates the inside of the upper breather chamber 15 with the atmosphere.
(fitted into the fitting hole 15a),
The lower breather chamber 16 is provided with a gas introduction hole 19 in its bottom wall 16c. Therefore, the exhaust gas G filling the crankcase 1 flows from the gas introduction hole 19 into the first chamber 16f of the lower breather chamber 16, as shown by the arrow, and flows from the second chamber 16g to the communication chamber 1.
6d → flows sequentially through the upper breather chamber 15 and is discharged from the outlet pipe 18 into the atmosphere. At this time, the exhaust gas G flows into the first chamber 1 of the lower breather chamber 16.
6f and the second chamber 16g, the volume of the lower breather chamber 16 gradually increases, causing the exhaust gas G to expand and its flow velocity to decrease. Furthermore, when the exhaust gas G flows through the communication chamber 16d to the upper breather chamber 15, its flow direction changes approximately at right angles, and the flow direction changes between the chambers 15, 1.
It will collide with the wall in 6th class. In this way, exhaust gas G
In the process of passing through the breather device 13, the flow of gas is decelerated and the direction changes, so that the gas and oil are efficiently separated due to the difference in the gravitational effect due to the difference in mass between the gas and oil. The separated oil flows back into the crankcase 1 through the gas introduction hole 19 and functions as lubricating oil again.

Note that near the gas introduction hole 19 of the bottom wall 16c, oil scraped up from the transmission gears 11 and 12 flows from the gas introduction hole 19 into the lower breather chamber 1.
6 Oil guard 20 to prevent oil from entering inside
is provided.

As mentioned above, the breather chamber 14 is composed of the upper breather chamber 15 formed in the lower part of the cylinder head 2 and the lower breather chamber 16 formed in the upper part of the crankcase 1, so that the exhaust gas G flows. In addition to increasing the length of the chamber in the direction of travel, the breather chamber can be placed at the rear of the motorcycle in the direction of travel, in other words, in a position where it is less likely to be exposed to the traveling wind, which eliminates cooling caused by the traveling wind and improves the separation effect between exhaust gas and oil. be able to. Furthermore, since the volume gradually increases from the inlet side to the outlet side, the flow velocity of exhaust gas entering the breather chamber decreases, and the flow direction is bent due to the curved exhaust gas passage, further improving the separation effect between exhaust gas and oil. can. Further, since both the breather chambers 15 and 16 are provided near the engine combustion chamber, the flow rate of the exhaust gas G is high due to the heat thereof, and the oil droplet separation function is further promoted. Also, since a part of the breather chamber 14 is located on the cylinder head 2 side, it is not affected by installation space constraints due to the arrangement of elements (mission gears 11, 12, etc.) installed in the crankcase 1. Moreover, the crankcase 1 does not have to be enlarged. In particular, since the second breather chamber is provided close to the first breather chamber at the upper part of the crankcase above the transmission chamber, communication between the two chambers is easy, and the first breather chamber is connected to the cylinders of one bank of the engine. Since it is installed on the side wall on the opposite bank side of the head, the engine does not become larger or more complex.

(Effects of the invention) In summary, the V for motorcycles according to this invention
A breather device for an internal combustion engine of a motorcycle includes a first breather chamber provided in a cylinder head of the internal combustion engine and a second breather chamber provided in a crankcase, comprising: (a) the internal combustion engine; is a V-type internal combustion engine, (b) the first breather chamber is provided on a side wall of the cylinder head of one bank of cylinders of the engine on the side opposite to the other bank, and (c) the second breather chamber is provided in an upper part of the crankcase above the transmission chamber so as to communicate with the first breather chamber; (e) Since the second breather chamber has a shape in which the volume gradually increases from the inlet side to the outlet side, the crankcase The chamber length in the direction in which exhaust gas flows can be set to be large without being affected by installation space restrictions due to the arrangement of elements installed inside the engine, and without increasing the size of the crankcase. Therefore, it is possible to promote the separation of oil droplets mixed in exhaust gas without making the crankcase complicated and large.

Further, since the breather chamber can be provided at the rear of the motorcycle in the traveling direction, that is, at a position where it is difficult to be exposed to the wind while traveling, the effect of separating exhaust gas and oil can be further improved without cooling caused by the wind. Furthermore, the flow velocity of the exhaust gas entering the breather chamber decreases and the flow direction is curved, so
The effect of separating exhaust gas and oil can be further improved. In addition, since the breather chamber can be installed near the combustion chamber, the flow of exhaust gas is promoted by its heat, and the effect of separating exhaust gas and oil can be further improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a V-type internal combustion engine for a motorcycle to which an embodiment of this invention is applied, and FIG. 2 is an enlarged view of the main parts of FIG. 1. 1... Crank case, 2... Cylinder head, 13... Breather device, 14... Breather chamber, 15... Upper breather chamber (first breather chamber),
16...Lower breather chamber (second breather chamber), 1
6d...Communication room.

Claims (1)

[Claims for Utility Model Registration] A breather device for an internal combustion engine of a motorcycle comprising a first breather chamber provided in the cylinder head of the internal combustion engine and a second breather chamber provided in the crankcase, comprising: (a) the internal combustion engine; is a V-type internal combustion engine, (b) the first breather chamber is provided on a side wall of the cylinder head of one bank of cylinders of the engine on the side opposite to the other bank, and (c) the second breather chamber is provided in an upper part of the crankcase above the transmission chamber so as to communicate with the first breather chamber; (e) The second breather chamber has a shape whose volume gradually increases from its inlet side to its outlet side. Breather device for internal combustion engines of motorcycles.