JP3052365B2 - Engine breather structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a breather structure of an engine provided in an engine case.

(Prior Art) For example, in a motorcycle engine, a crack shaft, a transmission, and the like are generally housed in the same engine case in order to make the entire engine compact. Lubricating oil is sealed in the engine case to smoothly operate the internal devices such as the crankshaft and the transmission. During operation of the engine, the lubricating oil is vigorously stirred in the engine case by internal devices such as a crankshaft and a transmission, and becomes a mist oil mist. This oil mist mixes with the high-temperature blow-by gas leaking from the gap between the cylinder and the piston, and fills the engine case.

On the other hand, the pressure in the engine case constantly fluctuates as the piston moves up and down. Therefore, when the engine case is sealed, the pressure in the engine case hinders the movement of the piston. Therefore, it is necessary to provide a breather hole in the engine case for releasing the pressure in the engine case to the outside.

However, since the above-mentioned oil mist gas is filled in the engine case, if a breather hole is formed in the engine case, the oil mist gas blows out from the breather hole, resulting in oil shortage.

Therefore, conventionally, a breather chamber provided with this breather hole at the end of the maze-shaped room is provided in the engine case, and the distance and volume from when oil mist gas enters this breather chamber until it escapes outside is increased. Means have been taken to separate the oil component from the air, return the oil component into the engine case, and release only the gas out of the engine case.

As the internal volume of the breather chamber increases, the action of separating oil mist gas into oil and gas increases as it increases. However, in engines that must be made small, such as motorcycle engines, they are large in one place. It is difficult to provide a breather chamber with an internal volume. In order to solve this, conventionally, a method of providing a plurality of small-volume breather chambers by utilizing a dead space or the like inside the engine and communicating them with each other has been adopted in many cases. FIG. 5 and FIG. 6 show an example of a motorcycle engine having a plurality of breather chambers as described above (see Japanese Patent Application Laid-Open No. 58-204910).

In the engine 1, the clutch chamber 3 and the transmission chamber 4 in the engine case 2 communicate with each other through a communication hole 6 provided in a partition wall 5, and lubricating oil 7 enters the engine case 2 through the communication hole 6. It is evenly distributed. The engine case 2 has two breather chambers.

The first breather chamber 8 is provided in a dead space 11 formed at a step due to a difference in outer diameter between the primary driven gear 9 and the oil pump driving gear 10 in the clutch chamber 3.
The first breather chamber 8 is partitioned by a partition plate 12 that covers the upper half of the oil pump driving gear 10, a partition plate 13 that rises up from the partition plate 12 and reaches the upper part of the engine case, and a dead space 11 as a primary space. The partition plate 14 shields from the driven gear 9. The partition plate 14 is fixed to the partition plate 13 by screws 15. These partition plates prevent oil from directly entering the first breather chamber 8.

The second breather chamber 16 is separated from the first breather chamber 8 by the partition wall 5.
And at the uppermost part of the engine case on the opposite side, and communicates with the first breather chamber 8 through a plurality of communication holes 17 formed in the partition wall 5. The second breather chamber 16 can enter only through this communication hole 17. A breather pipe 19 connected to the outside of the engine case 1 is disposed on the ceiling of the second breather chamber 16.

With the above-described structure, when the oil mist gas in the engine case 1 is released to the outside due to a pressure increase, the oil mist gas flows from the opening 18 to the first breather chamber 8.
Then, it flows into the second breather chamber 16 through the communication hole 17 of the partition wall 5. In the second breather chamber 16, the flow rate of the oil mist gas decreases, and the oil mist gas is separated into oil and gas. The separated oil returns to the clutch chamber 3 through the lowermost communication hole 17. Further, the gas is discharged to the outside through a breather pipe 19 formed in the second breather chamber 16 or is sucked into an air cleaner.

(Problems to be Solved by the Invention) However, in the case where such a breather chamber type of breather chamber is provided, in order to improve the oil separation and the dropping property of the oil mist gas in the breather chamber, the respective breather chambers must be sequentially arranged. It is necessary to arrange it at a higher position, and the breather chamber at the last stage tends to be located at the top of the engine case. In particular, in the case of a motorcycle engine, auxiliary equipment such as an engine starter, an intake device, and a battery must be disposed above the engine case, so that there is no room for space. Therefore, the shape in which the upper part of the engine case projects by the breather chamber is not preferable in view of the layout of the auxiliary equipment. In addition, the structure of the engine case becomes complicated, resulting in high costs.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described problems, and has as its object to provide a breather structure of an engine that can perform a sufficient breathing function even with a single breather chamber having a simple structure.

[Configuration of the invention]

(Means for Solving the Problems) In order to achieve the above object, according to the first aspect of the present invention, lubricating oil is housed in a clutch chamber and a transmission chamber that house at least a primary driven gear and an oil pump drive gear, and these two chambers are used. In a breather structure of an engine provided with an engine case in which a communication hole for communicating these two spaces with a partition wall disposed therebetween is provided, due to an outer diameter difference between the primary driven gear and the oil pump drive gear in the clutch chamber, A step formed on these side surfaces, and a space formed between the upper portions of the partition walls,
A seal plate provided in the flat breather chamber attached to the partition so as to shield from these gears, a plurality of outlets formed in the seal plate so as to be vertically separated from each other, and an upper portion of the breather chamber. A breather pipe communicating with the outside of the engine case, wherein the plurality of outlets include an outlet opening in a direction orthogonal to a blow-by gas flow flowing into the breather chamber from another outlet. It is characterized by.

According to the first aspect of the present invention, the breather chamber is narrow and flat formed between the step portion formed on the primary driven gear and the oil pump driving gear and the upper side surface of the partition wall due to the difference in outer diameter. It is formed by a dead space. That is, since the breather chamber is formed by utilizing the dead space of the clutch chamber and has a flat shape along the partition wall, it is possible to suppress an increase in the size of the clutch chamber and thus the engine case.

The blow-by gas flows into the breather chamber from a plurality of outlets of the seal plate.However, these blow-by gas streams collide or interfere with each other in a flat and narrow breather chamber in an orthogonal direction. The vortices collide with each other or interfere with each other, and the flow velocity decreases. For this reason, the oil component in the blow-by gas is separated and falls from the discharge port into the oil reservoir of the engine case and is returned.

As described above, the blow-by gas flows respectively flowing into the breather chamber from the plurality of outlets collide or interfere with each other in a flat and narrow breather chamber from an orthogonal direction to generate a vortex, which greatly reduces the flow velocity. The separation efficiency of the oil can be improved. In addition, since the collision or interference of the blow-by gas flows in the orthogonal direction is performed in a flat and narrow breather chamber, the vortex generation efficiency is high, and the oil separation efficiency is further increased accordingly. Therefore, there is no need to provide a plurality of breather chambers, and the breather structure is simple, so that the manufacturing cost of the engine case can be reduced.

On the other hand, the blow-by gas from which the oil has been separated is discharged to the outside of the engine case through the breather pipe, and reduces the pressure in the engine case.

The invention according to claim 2 is characterized in that the seal plate is fixed to a mounting boss protruding from the partition wall and extending into the breather chamber, and discharge ports are disposed vertically above and below the mounting boss.

According to the second aspect of the present invention, since the plurality of mounting bosses for mounting the seal plate to the partition wall protrude into the breather chamber, the blow-by gas flowing into the breather chamber collides with these mounting bosses, so that a vortex is more likely to be generated. As a result, the oil separation efficiency can be further improved.

(Embodiment) An embodiment of a breather structure of an engine according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 and FIG. 2 show an engine 21 of a motorcycle having a breather chamber according to the present invention. This engine 21
The clutch chamber 23 and the transmission chamber 24 in the engine case 22 communicate with each other through a communication hole 26 provided in a partition wall 25, and the lubricating oil 27 spreads evenly into the engine case 22 through the communication hole 26. I have.

In the engine case 22, a breather chamber 31 is formed in a dead space 30 formed on a side of a step formed on a side surface of the primary driven gear 28 and an oil pump driving gear 29 in the clutch chamber 23 due to a difference in outside diameter. doing.
The breather chamber 31 is formed in the upper half around the oil pump gear 29 by a substantially fan-shaped seal plate 32 that shields the dead space 30 from the primary driven gear 28 and the oil pump drive gear 29. Seal plate 32
Is fixed to the partition wall 25 by fastening three screws 33 to a plurality of bosses protruding from the partition wall 25, and has a main exhaust port 34 into which oil mist gas in the engine case 22 flows in at the lowermost portion. This oil mist gas is supplied to the engine case 22
The blow-by gas inside contains lubricating oil.

On the other hand, a sub-discharge port 35 is formed substantially at the center of the seal plate 32. Inside the top of the breather chamber 31, there is a breather pipe connected to the outside of the engine case 22.
The breather pipe 36 has an inner open end projecting into the breather chamber 31. In addition, breather room 31
A communication hole 37 for returning oil separated and falling in the breather chamber 31 to the transmission chamber 24
Are provided on the partition wall 25.

When the oil mist gas in the engine case 22 is released to the outside due to the pressure increase, the oil mist gas flows into the breather chamber 31 from the main discharge port 34 and the sub discharge port 35 of the seal plate 32. As shown in FIGS. 3 and 4, inside the breather chamber 31, oil mist gas flows almost simultaneously from the upper auxiliary outlet 35 and the lower main outlet 34, and these oil mist gas flows are orthogonal to each other. A vortex is formed by collision or interference in the direction, and the flow velocity of the oil mist gas decreases. For this reason, the oil component in the oil mist gas separates from the gas due to the difference in specific gravity and falls downward.
The oil that has fallen is returned from the main discharge port 34 and the communication hole 37 to the oil sump below the engine case 22. Further, the oil mist gas flowing into the breather chamber 31 is
Even if the swirling flow collides with a plurality of mounting bosses protruding into the interior 31, the swirling currents also collide with each other and interfere with each other to further reduce the flow velocity, so that the oil separation efficiency can be further improved. On the other hand, the gas after the oil component is separated and dropped is discharged to the outside through a breather pipe 36 protruding from the top of the breather chamber 31 or is taken into the air cleaner.

By using the breather chamber having the above configuration and operation, the proportion occupied by the breather chamber in the engine case can be minimized, so that it is not necessary to provide a plurality of breather chambers. Therefore, since the second breather chamber does not protrude above the engine case, the space above the engine case can be effectively used, and the starter 38 for starting the engine and the like as shown in FIGS. 1 and 2 can be used. Auxiliary equipment can be arranged without difficulty.

〔The invention's effect〕

According to the present invention as described above, the breather chamber is
Due to the difference in outer diameter between the primary driven gear and the oil pump drive gear, a narrow and flat dead space formed between a step formed on these side surfaces and an upper side surface of the partition wall. That is, the breather chamber is formed by utilizing the dead space of the clutch chamber, and
Since it has a flat shape along the partition, it is possible to suppress an increase in the size of the clutch chamber and thus the engine case.

The blow-by gas flows into the breather chamber from a plurality of outlets of the seal plate.However, these blow-by gas streams collide or interfere with each other in a flat and narrow breather chamber in an orthogonal direction. The vortices collide with each other or interfere with each other, and the flow velocity decreases. For this reason, the oil component in the blow-by gas is separated and falls from the discharge port into the oil reservoir of the engine case and is returned.

As described above, the blow-by gas flows respectively flowing into the breather chamber from the plurality of outlets collide or interfere with each other in a flat and narrow breather chamber from an orthogonal direction to generate a vortex, which greatly reduces the flow velocity. The separation efficiency of the oil can be improved. In addition, since the collision or interference of the blow-by gas flows in the orthogonal direction is performed in a flat and narrow breather chamber, the vortex generation efficiency is high, and the oil separation efficiency is further increased accordingly. Therefore, there is no need to provide a plurality of breather chambers, and the breather structure is simple, so that the manufacturing cost of the engine case can be reduced.

On the other hand, the blow-by gas from which the oil has been separated is discharged to the outside of the engine case through the breather pipe, and reduces the pressure in the engine case.

According to the second aspect of the present invention, since the plurality of mounting bosses for mounting the seal plate to the partition wall protrude into the breather chamber, the blow-by gas flowing into the breather chamber collides with these mounting bosses, so that a vortex is more likely to be generated. As a result, the oil separation efficiency can be further improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a breather structure of an engine according to the present invention, FIG. 2 is a sectional view taken along the line AA of FIG.
FIG. 3 is an operation view of a breather chamber of the engine according to the present invention, FIG. 4 is a cross-sectional view taken along the line BB of FIG. 3, FIG. 5 is a cross-sectional view showing an example of a conventional engine breather structure, FIG. 6 is a sectional view taken along the line CC of FIG. 2,22 …… engine case, 13,16,31 …… breather room, 34
…… Main outlet, 35… Sub outlet.

Claims (2)

(57) [Claims] 1. A lubricating oil is accommodated in a clutch chamber and a transmission chamber accommodating at least a primary driven gear and an oil pump driving gear, and a communication hole for communicating these two spaces is formed in a partition provided between the two chambers. In the breather structure of the engine having the engine case provided, the outer diameter difference between the primary driven gear and the oil pump drive gear of the clutch chamber causes the stepped portion formed on these side surfaces and the upper part of the partition wall to A seal plate formed in a flat breather chamber attached to the partition so as to shield the formed space from these gears, and a plurality of outlets formed in the seal plate so as to be vertically separated from each other, A breather pipe that communicates the upper part of the breather chamber with the outside of the engine case, Breather structure for an engine number of outlet, which to blow gas stream flowing into the breather chamber from the other outlet, characterized in that it comprises an outlet opening to the orthogonal orientation. 2. The seal plate according to claim 1, wherein the seal plate is fixed to a mounting boss protruding from the partition wall and extending into the breather chamber, and discharge ports are disposed vertically above and below the mounting boss. Engine breather structure.