JP3109372B2 - Breather structure of four-cycle engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a breather structure for a four-stroke engine in which a transmission (multi-stage gear transmission) is integrally provided at the rear of an engine case used for a motorcycle, for example.

[0002]

2. Description of the Related Art In an engine used for a motorcycle or the like, a transmission chamber is integrally formed at a rear portion of an engine case, and a transmission is accommodated in the transmission chamber, thereby making the engine compact.

[0003] In the case of a four-stroke engine, it is necessary to prevent the pressure in the crank chamber from rising by, for example, releasing blow-by gas generated in the crank chamber to the outside of the crank chamber.
In this case, if the blow-by gas is directly discharged to the outside of the crank chamber, the oil mixed in the blow-by gas is also discharged together, and the oil consumption rate is deteriorated.
For this reason, a breather chamber is provided, and gaseous gas and liquid wet oil are separated (gas-liquid separation) in the breather chamber, and only the gas amount is collected and reused on the engine intake side.

[0004] In the case of a four-cycle engine, a breather chamber is generally provided in a cylinder head cover at the upper end of the engine. For example, see Japanese Utility Model Application Laid-Open No. 61-204908.

In some motorcycle engines, a breather chamber is provided above a transmission chamber on the rear upper surface of an engine case. For example, see JP-A-4-159410.

In some cases, a breather chamber is provided in a gap between a side wall of an engine case and a clutch in a side cover. For example, see JP-A-5-52109.

Further, there is a type in which a breather chamber is provided in a small gap between the side wall of the engine case and the clutch, and a second breather chamber is provided above the transmission chamber to communicate with each other.
For example, see Japanese Patent Publication No. Sho 62-21967.

[0008]

However, in the conventional breather structure, the one in which the breather chamber is provided in the cylinder head has a large engine height, and is not suitable for the one that requires miniaturization such as a motorcycle. .

[0009] When the breather chamber is provided above the transmission chamber, the shape is restricted when a starter motor is mounted above the transmission chamber, and the structure becomes complicated. Further, the upper portion of the transmission chamber has a large amount of oil mist, and the sealing structure is complicated, which may increase the cost.

When the breather chamber is provided in the gap between the side wall of the engine case and the clutch, the breather chamber has a small volume, and the gas-liquid separation performance may be deteriorated. Also, the one having two breather chambers is complicated and costly.

In addition, as shown in FIG. 4 of the publication, it is necessary to position the packing on the breather plate in advance and mount it on the breather plate as shown in FIG. .

In view of the foregoing, it is an object of the present invention to provide a breather structure of a four-stroke engine which has a large capacity of a breather chamber to improve gas-liquid separation performance, and has a small engine size and a low cost. As an issue.

[0013]

The present invention has the following arrangement to solve the above-mentioned problems. That is, the present invention includes a transmission chamber which is encapsulated in the clutch chamber and the transmission to be encapsulated clutch is provided integrally with the engine case across the partition wall, this engine case
It consists of an upper case and a lower case,
The par case and the lower case are fixed with the tightening bolts.
An engine that is constant, the four breather chamber provided in the upper case to discharge the blow-by gas in the engine case only gas component out of the engine case support
In the breather structure of the vehicle engine ,
The upper part is recessed above the transmission chamber to provide a recess, and the opening of this recess on the clutch chamber side is closed with a breather cover.
Forming a breather chamber; and
A boss is formed to form a bolt hole for the tightening bolt.
Project the bolt seat surface at the upper end of the boss into the breather chamber.
It is a breather structure of a four-stroke engine characterized by being positioned so as not to be located .

Further, a tightening bolt provided on the engine case is provided.
Breather of the upper case located immediately above the
-A screw hole is provided in the upper wall portion of the chamber, and the screw hole
You may enable it to insert and remove a fastening bolt.

A gasket is interposed between the opening of the recess on the clutch chamber side and the breather cover.
Forming a projection protruding toward the clutch chamber side in the recess,
The projection may be fitted into a hole provided in the gasket to position the gasket.

[0016]

The recess forming the breather chamber is formed by recessing the partition wall from the clutch chamber to above the transmission chamber, so that the capacity of the breather chamber is increased to improve the gas-liquid separation performance. be able to. If the bolt seat surface of the boss portion forming the fastening bolt hole is located in the breather chamber, the volume occupied by the boss portion in the breather chamber can be reduced. Also, by forming a projection protruding toward the clutch chamber side in the recess, and fitting this projection into a hole provided in the gasket to position the gasket, the positioning of the gasket can be easily performed and the breather cover of the breather cover can be easily formed. Can be easily attached and detached.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 1, the engine case of the four-stroke engine according to the present embodiment is cast using a light alloy, and the center portion is divided into upper and lower cases of an upper case 1 and a lower case 2. The surface is coated with a liquid packing or the like and sealed, and a plurality of tightening bolts 3
Fasten using.

As shown in FIG. 3, in the engine case, a clutch chamber 12a and the like containing the clutch 12 and a transmission chamber 6 and the like containing the transmission are integrated with the engine case with the right partition 4 interposed therebetween. As shown in FIG. 2, the inside of the partition 4 has a crank chamber 5 at the front and a transmission chamber 6 at the rear. As shown in FIG. 1, a crankshaft hole 7, a countershaft hole 8, and a drive shaft hole 9 are formed in the partition wall 4 from the front part. The drive shaft is rotatably mounted via bearings. On the lower surface of the lower case 2,
The oil pan is connected and a predetermined amount of lubricating oil is filled.
Lubricating oil is supplied to each part of the engine by an oil pump linked to the engine.

As shown in FIG. 3, a side case 10 cast and formed from a light alloy is attached to the partition 4 using a plurality of fastening bolts. A primary reduction gear 11 and a clutch 12 are provided inside the side case 10. In addition, the counter shaft 13 and the drive shaft that pass through the mission chamber 6 include:
The transmission gear 14 is mounted.

In this embodiment, as shown in FIGS. 1 and 3, the partition 4 of the upper case 1 is moved from the upper side around the drive shaft hole 9 to the upper side around the counter shaft hole 8 from the clutch chamber 12a. A recess 15 is provided to be recessed over the transmission chamber 6. This recess 15
The inside may be divided into a plurality of parts by protruding ribs or the like. Also, recess 1
5 and the transmission chamber 6 may be communicated with each other through a hole 16 or the like.

Further, the clutch chamber 12 of the recess 15 is formed.
The opening on the a side is connected to the breather cover 18 shown in FIGS.
To close the recess 15 and the breather cover 18
And a breather chamber 19 is formed between them. As shown in FIG. 3, a gasket 17 is interposed between the opening on the clutch chamber 12a side and the breather cover 18, and the breather cover 18 is fastened using two bolts. On the upper wall of the breather chamber 19, a union pipe 20
Is installed by driving. Union pipe 20
Is connected to an air cleaner with a vinyl pipe.

The gasket 17 may be made of a rubber plate. As shown in FIG. 7, a bolt hole 22 is provided in accordance with the bolt hole 21 of the breather cover 18 and fastened together with the breather cover 18. As shown in FIG. 3, the upper case 1 is provided with two protrusions 23 projecting sideways, and the protrusions 23 are fitted into the holes 24 of the gasket 17 shown in FIG. It can be easily attached.
Further, the gasket 17 may be simply pressed against the opening of the recess 15 on the clutch chamber 12a side by the breather cover 18 without providing the bolt hole 22 or the hole 24 in the gasket 17. The breather cover 18 includes
A ventilation hole 25 for breathing is provided.

In general, the upper case 1 and the lower case 2 are screwed into the lower case 2 by passing the tightening bolts 3 through the tightening bolt holes 26 from the upper surface of the upper case 1 as shown in FIG. . This way,
The boss portion 26a forming the tightening bolt hole 26 in the breather chamber 19 is exposed in a columnar shape, and the volume of the breather chamber 19 is reduced, or the breather chamber 19 is divided.

Therefore, in this embodiment, as shown in FIG. 8, the bolt seating surface 26a1 at the upper end of the boss 26a is formed.
Is located on the lower surface of the breather chamber 19 (an example in the breather chamber 19) so that the boss portion 26a does not protrude into the breather chamber 19.

When the tightening bolt 3 cannot be inserted from the side of the upper case 1, the screw hole 2 is formed in the upper wall portion of the breather chamber 19 immediately above the tightening bolt hole 26.
7a is provided, and the plug bolt 27 can be attached to and detached from the screw hole 27a with the packing 28 interposed therebetween, and the tightening bolt 3 can be inserted and removed through the screw hole 27a.

With this configuration, in this embodiment, blow-by gas generated in the engine case is collected in the breather chamber 19, sent from the union pipe 20 to the air cleaner via the pipe, and included in the intake gas and re-used. Used.

As described above, according to the breather structure of the four-cycle engine of the present embodiment, the recess 15 forming the breather chamber extends from the upper side around the drive shaft hole 9 to the upper side around the counter shaft hole 8. Since the partition wall 4 of the upper case 1 is formed so as to be recessed from the clutch chamber 12a to above the transmission chamber 6, the breather chamber 1
The gas-liquid separation performance can be improved by increasing the volume of No. 9 and the consumption of lubricating oil can be reduced.

Further, the positioning of the gasket 17 can be easily performed, the attachment and detachment of the breather cover 18 can be easily performed, the cost can be reduced, and the size of the engine can be reduced. Since the bolt seating surface 26a1 of the boss portion 26a forming the tightening bolt hole 26 is located on the lower surface of the breather chamber 19, the boss portion 26a in the breather chamber 19 hardly reduces the volume in the breather chamber 19. Disappears. This also makes it possible to increase the volume of the breather chamber 19.

If the breather chamber 19 is divided by ribs or the like, the gas-liquid separation effect can be further enhanced. In addition, the communication between the breather chamber 19 and the mission chamber 6 allows the breather chamber 19 to also serve as a breather for the mission chamber 6.

The present embodiment is a preferred embodiment of the present invention, and the technical scope of the present invention is not limited to this embodiment. Even if the gasket 17 is not made of a rubber plate, it is also within the technical scope of the present invention, even if the gasket 17 is formed by thinly bonding a urethane foam or a rubber layer to a thin plate. In addition, the breather structure of the four-cycle engine of the present invention is applicable to, for example, a four-cycle engine used for a motorcycle engine, a four-wheel automobile engine, and various other internal combustion engines.

[0031]

As described above, according to the present invention,
Since the gas-liquid separation performance can be improved by increasing the volume of the breather chamber, the consumption of lubricating oil can be reduced. Further, since the volume occupied by the boss portion in the breather chamber can be reduced, the volume of the breather chamber can be increased from this point as well. Further, the positioning of the gasket can be easily performed, the attachment and detachment of the breather cover can be easily performed, and the cost can be reduced. In addition, by separating the breather chamber with ribs or the like, the separation effect is enhanced, and the breather chamber communicates with the mission chamber, so that the breather chamber can also serve as a breather.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of the present invention in which an upper case is overlaid on a lower case.

FIG. 2 is a plan view of an upper case showing the embodiment of the present invention.

FIG. 3 is a sectional view of a breather chamber showing an embodiment of the present invention.

FIG. 4 is a front view of a breather cover according to the embodiment of the present invention.

FIG. 5 is a plan view of a breather cover according to the embodiment of the present invention.

FIG. 6 is a front view of a gasket showing an embodiment of the present invention.

FIG. 7 is a front view of a gasket showing another embodiment of the present invention.

FIG. 8 is a sectional view showing a tightening bolt in a breather chamber according to the embodiment of the present invention.

FIG. 9 is a sectional view showing a tightening bolt of a general upper and lower case.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper case 2 Lower case 3 Tightening bolt 4 Partition wall 6 Mission chamber 9 Drive shaft hole 10 Side cover 12 Clutch 12a Clutch chamber 15 Depression 17 Gasket 18 Breather cover 19 Breather chamber 20 Union pipe 23 Projection 24 hole 26 Tightening bolt hole 26a Boss Part 26a1 Bolt bearing surface 27 Plug bolt

Claims (3)

(57) [Claims] 1. A and the transmission chamber to be encapsulated in the clutch chamber and the transmission to be encapsulated clutch is provided integrally with the engine case across the partition wall, the engine
If the case consists of an upper case and a lower case,
And upper case and lower case
The engine is fixed, and the breather chamber for discharging only gas components from the blow-by gas in the engine case to the outside of the engine case is provided in the upper case.
-In the breather structure of the four-cycle engine provided in the case, the upper part of the partition is recessed above the transmission chamber to form a recess, and the clutch chamber side opening of the recess is closed with a breather cover to form a breather chamber, And the upper case
The boss part which forms the bolt hole of the tightening bolt
The bolt seat surface at the upper end of the boss portion is connected to the breather chamber.
The breather structure of the four-stroke engine, which is positioned so that it does not protrude into the interior . 2. A tightening bolt provided on the engine case.
Breather of the upper case located just above the hole
A screw hole is provided in the upper wall of the room, and the screw hole
2. The mounting bolt can be removed and inserted.
The breather structure of the described four-cycle engine. 3. A gasket is interposed between the opening of the dent portion on the clutch chamber side and the breather cover, and a projection is formed in the dent portion so as to project toward the clutch chamber, and the projection is provided on the gasket. 3. The breather structure for a four-stroke engine according to claim 1, wherein the gasket is positioned by being fitted in the hole.