JPH0515525Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an engine breather device that communicates the transmission chamber of the engine with the outside.

[Prior Art] For example, oil is stored in a transmission chamber of an engine, that is, a transmission chamber, in order to lubricate gears of the transmission and the like.

While the engine is operating, the air inside the transmission chamber expands thermally as the temperature rises, increasing the pressure. Therefore, the thermally expanded air is forced to flow out of the mission room. At this time, the thermally expanded air is introduced into the breather chamber and then flows out into the atmosphere from the breather hole provided in this breather chamber. For example, see Utility Model Publication No. 52-42498). In this way, by interposing the breather chamber between the mission chamber and the breather hole, oil mist is separated from the outflowing air, and
This prevents oil splashed by the gears in the transmission chamber from being directly blown out from the breather hole.

Furthermore, when a breather chamber is interposed between the transmission chamber and the breather hole as described above, for example, as disclosed in Japanese Patent Application Laid-open No. 121812/1983, the breather chamber is placed opposite the crank chamber. Compared to the case where the breather chamber is disposed in the same direction, the length of the breather chamber, that is, the distance for separating the oil mist can be made longer, and oil and gas separation can be improved.

However, since the breather chamber is provided to protrude above the transmission chamber, the engine becomes larger.

Conventionally, in order to improve this, for example,
As disclosed in Japanese Patent No. 62-28010, a breather chamber is formed in the concave constriction of the connection between the lower part of the cylinder head and the upper part of the crankcase, corresponding to the upper part of the transmission chamber. Are known.

[The problem that the idea aims to solve]

However, according to the above configuration, the breather chamber is formed in a separate joint between the cylinder head and the crankcase, and the transmission chamber and the breather chamber are closed by a member separate from the crankcase. Complex manufacturing and assembly structure.

In addition, because the mission chamber and the breather chamber are airtightly closed by separate closing members, the airtight structure deteriorates due to mechanical and thermal fatigue, and oil mist leaks from the closed section, causing oil and gas separation. becomes difficult.

In particular, the breather chamber configured as described above is formed in the plane perpendicular to the crankshaft at the joint between the cylinder head and the crankcase, so the length of the breather chamber cannot be very long, and oil mist separation is more difficult.

This invention was made in order to improve the above-mentioned problems, and the object is to provide an engine breather device that is easy to manufacture and assemble, and can improve the separation of oil mist.

[Means to solve the problem]

The breather device according to this invention has a transmission chamber, a crank chamber, and a breather chamber integrally formed in the crankcase, and the breather chamber is connected to a wall of the transmission chamber, a wall of the crank chamber, and a an outer wall extending over the outer sides of both walls, and an elongated hole extending in the longitudinal direction of the crankshaft at the upper corner of the concavely constricted connection between the transmission chamber and the crank chamber; Further, one end thereof is open to a clutch chamber communicating with the transmission chamber, the other end is closed, and a breather hole is formed near the closed other end.

[Effect]

According to the above configuration, since the transmission chamber, the crank chamber, and the breather chamber are integrally formed in the crankcase, manufacturing and assembly thereof are easy.

In addition, since the breather chamber is integrated with the crankcase, it is possible to ensure an airtight structure with the transmission chamber, preventing oil mist from leaking into the breather hole through a short path, improving oil-gas separation. do.

Furthermore, the breather chamber is formed into a long hole shape in the longitudinal direction of the crankshaft, and one end thereof opens into the clutch chamber communicating with the transmission chamber, and the other end is closed, and the other end of the breather chamber is closed. Since the breather hole is formed in the vicinity of the breather chamber, the length of the breather chamber becomes longer, and oil mist separation is further improved.

Furthermore, since the breather chamber is formed by the wall of the transmission chamber, the wall of the crank chamber, and the outer wall extending between the two walls, the connecting portion is reinforced by the outer wall.

[Example] An example of this invention will be described below with reference to the drawings.

In FIG. 1, 1 is a crankcase of a two-stroke engine, in which a transmission chamber 2 and a crank chamber 3 are integrated. A clutch cover 4 and a transmission cover 5 are attached to the crankcase 1, and the inside of the clutch cover 4 becomes a clutch chamber 4a.

A crankshaft 6 is disposed within the clutch chamber 3,
A transmission T is disposed within the transmission chamber 2, and the transmission T is adjacent to the crankshaft 6 in the radial direction. The crankshaft 6 is rotatably supported by the crankcase 1, and the drive shaft 7 and the power take-off shaft 8, which is a driven shaft, of the transmission T are rotatably supported by the crankcase 1 and the transmission cover 5. has been done. 9 is a kick starter shaft.

A clutch 10 is attached to one end of the drive shaft 7, and a gear 1 is attached to one end of the crankshaft 6 for transmitting the drive of the crankshaft 6 to the clutch 10.
1 is fixed. Above gear 11 and clutch 1
0, the driving force of the crankshaft 6 is transferred to the drive shaft 7.
is transmitted to.

Six variable speed drive gears are arranged on the drive shaft 7 as a gear train 70. On the other hand, six variable speed driven gears meshing with the gear train 70 are arranged as a gear train 80 on the power take-off shaft 8 . This transmission T has the gear trains 70, 8
0 determines the transmission path of the driving force from 1st speed to 6th speed and outputs it from the sprocket 12.

20 is a breather chamber, and 21 is a breather hole. As shown in FIG. 2, which shows a cross section taken along the - line in FIG.
, the wall 3a of the crank chamber 3, and both walls 2a, 3
It is formed by an outer wall 22 that spans a and is provided at an upper corner of a connecting portion 23 between the mission chamber 2 and the crank chamber 3. The breather hole 21 is provided in the upper wall of the breather chamber 20. A pipe (not shown) is attached to this breather hole 21 to communicate the breather chamber 20 with the atmosphere. S in the figure is a cylinder. As shown in FIG. 3, which shows a cross section taken along the line -2 in FIG.
It communicates with the mission chamber 2 via a. Here, the clutch chamber 4a and the transmission chamber 2 are as follows:
Bearing portion 13 (first
Although not shown in the figure, they communicate around the area.

The breather chamber 20 is made of cast metal and integrally formed with the crankcase 1, and when it is formed, it is
The mold is cut in the direction (toward the clutch chamber 4a side).

An oil chamber 30 is provided in the upper part of the crankcase 1 in FIG. 2, and oil in the oil chamber 30 falls from an oil drop hole 31 to the gear trains 70 and 80 to lubricate them. . 3 in Figure 3
2 is an oil passage, and this oil passage 32 is
Oil receiver 32a provided on clutch cover 4
and an oil chamber 30 provided in the crankcase 1.
The oil chamber 3 receives the oil stirred up by the clutch 10 and is connected to the oil chamber 32b.
Supply to 0.

When forming the oil chamber 30, the oil chamber 30 is die-cut in the direction of arrow B (towards the mission cover 5), and the opening 30a after die-cut is closed by the mission cover 5.

In the above configuration, while the engine is operating, the air in the mission chamber 2 shown in FIG. 3 expands thermally as the temperature rises, and the pressure increases. The thermally expanded air in the mission chamber 2 does not directly flow out from the breather hole 21 into the atmosphere, but flows out from the breather hole 21 after passing through the clutch chamber 4a and the breather chamber 20. At this time, the thermally expanded air in the mission chamber 2 contains oil mist, but the oil and gas are separated when passing through the breather chamber 20.
Oil does not adhere to the breather hole 21. Further, the oil scattered by the gear trains 70 and 80 of the mission chamber 2 shown in FIG. 2 is not blown out from the breather hole 21.

Generally, the connecting portion 23 between the transmission chamber 2 and the crank chamber 3 is constricted, so the area around this connecting portion 23 has conventionally been a dead space that has not been effectively utilized. On the other hand, since the breather chamber 20 is provided at the upper corner of the connecting portion 23 between the mission chamber 2 and the crank chamber 3,
The breather chamber 20 makes effective use of dead space. Therefore, the breather chamber 20
does not protrude outward from the engine and does not cause the engine to become larger.

Further, the breather chamber 20 includes a wall 2a of the mission chamber 2, a wall 3a of the crank chamber 3, and both walls 2a of the transmission chamber 2.
Since it is formed by an outer wall 22 that spans between a and 3a, the outer wall 22 reinforces the connecting portion 23 between the mission chamber 2 and the crank chamber 3.

Furthermore, the breather chamber 20 and oil chamber 3 shown in FIG.
0 are formed adjacent to each other, they are cut out in opposite directions as shown by arrows A and B. Therefore, the breather chamber 20 and the oil chamber 30 have draft angles in opposite directions, so that the wall thickness W between the breather chamber 20 and the oil chamber 30 does not increase unnecessarily.

[Effects of the invention] As described above, according to this invention, the breather chamber effectively utilizes the space around the connecting portion between the transmission chamber and the crank chamber.

Furthermore, since the transmission chamber, crank chamber, and breather chamber are integrally formed in the crankcase, manufacturing and assembly are easy. Moreover, airtightness between the breather chamber and the transmission chamber is ensured for a long period of time, and oil mist is prevented from leaking out through a short path from the transmission chamber to the breather hole, improving oil-gas separation.

Furthermore, the breather chamber is formed into an elongated hole shape in the longitudinal direction of the crankshaft, and allows air containing oil mist in the transmission chamber to flow in from an opening at one end, and from a breather hole near the other end that is closed. Since the chamber is allowed to flow out, the length of the chamber is long, and the above-mentioned oil/gas separation is further improved. Furthermore, the connecting portion is reinforced by the outer wall of the breather chamber.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing an engine equipped with a breather device according to an embodiment of the invention, Fig. 2 is a sectional view taken along the - line in Fig. 1, and Fig. 3 is a -
FIG. 1...Crankcase, 2...Transmission room, 2a
...Transmission room wall, 3...Crank room, 3a...
Crank chamber wall, 4a...clutch chamber, 6...crankshaft, 10...clutch, 20...breather chamber, 20a...one end, 20b...other end, 21...
Breather hole, 22...Outer wall, 23...Connection part, T
……transmission.

Claims (1)

[Scope of utility model registration request] In an engine in which a clutch is disposed at one end of the crankshaft, and a transmission connected to the crankshaft via the clutch is disposed adjacent to the crankshaft in the radial direction, a transmission chamber is provided in the crankcase; A crank chamber and a breather chamber are integrally formed, and the breather chamber is connected to a wall of the transmission chamber,
The wall of the crank chamber and an outer wall that spans the outer sides of these walls are arranged so that the upper corner of the concavely constricted connection between the transmission chamber and the crank chamber is formed in the longitudinal direction of the crankshaft. It is characterized by being formed into an elongated hole, one end of which opens into a clutch chamber communicating with the transmission chamber, the other end of which is closed, and a breather hole is formed near the other end of the closed end. Engine breather device.