JPH07243319A - Breather cover structure for four cycle engine - Google Patents

Abstract

PURPOSE:To prevent an engine from enlarging in its size, and improve gas-liquid separating function of a breather chamber without increasing its cost, in an engine in which a balancer shaft is born in the vicinity of the cover of a breather chamber. CONSTITUTION:A device is provided with a bulk head 10b for separating into a transmission chamber formed in an engine case 10 and a clutch chamber 16, a breather cover 34 which is arranged on the clutch chamber 16 side of the bulk head 10b, in which the bulk head 10b (30) and a breather chamber 36 are formed, and in which an opening port 40 is penetrated, and a balancer shaft 28 for suppressing vibration of an engine. The balancer shaft 28 is formed in such constitution that the bearing end part thereof is arranged on the bulk head 10b facing to the circumference of the breather cover 34, and the end part 46 of the balancer shaft 28 side of the breather cover 34 is laminated with the bearing end part of the balancer shaft 28 in car body side surface direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a breather cover structure for a four-cycle engine, which separates an oil component mixed in blow-by gas and returns it to an oil pan to discharge the original blow-by gas to the outside of the engine. Breather cover structure.

[0002]

2. Description of the Related Art For example, in a motorcycle engine, a crankshaft, a transmission and the like are generally housed in the same engine case in order to make the entire engine compact. Lubricating oil for smoothly operating the above crankshafts, etc. is enclosed in this engine case, and when the engine is operating, this lubricating oil is vigorously agitated by the crankshafts, etc. and becomes mist-like oil mist. Become. This oil mist mixes with the blow-by gas leaking from the gap between the cylinder and the piston and fills the engine case. On the other hand, the pressure inside the engine case constantly fluctuates as the piston moves up and down, so that the pressure inside the engine case hinders the movement of the piston when the engine case is in a sealed state. Therefore, it is necessary to provide the engine case with a breather hole for releasing the pressure of the engine case to the outside.

However, since the engine case is filled with the above-mentioned oil mist gas, when a breather hole communicating directly with the outside is bored in the engine case, the oil mist gas blows out from the breather hole to cause a lack of oil. May invite you. Therefore, in the past, a breather chamber with a breather hole formed at the end of a labyrinth-like room was provided in the engine case, and the distance and volume from when the oil mist gas entered the breather chamber to the outside was set large. The means for separating the oil component and the gas component, returning the oil component to the inside of the engine case, and discharging only the gas component to the outside is adopted.

(1) The larger the volume of the breather chamber as described above, the greater the effect of separating oil and gas. In an engine that is required to be compact, such as a motorcycle engine, it is usual to form a breather chamber as wide as possible by utilizing the dead space of the engine. For example, as shown in FIGS. 9 to 10, a partition wall d between the mission chamber b and the clutch chamber c of the engine case a.
A breather cover e is attached from the side of the clutch chamber c to the chamber partitioned by the breather cover e and the partition wall d to form a breather chamber f (see Japanese Patent Laid-Open No. 4-159410). The breather cover e projects toward the clutch chamber c at a position avoiding the primary driven gear h fixed to the shaft (counter shaft) g1 of the clutch g and the oil pump drive gear i. Reference numeral j is a breather pipe that opens the breather chamber to the outside. In the above-mentioned publication, the openings (exhaust ports) o1 and o2 into which the oil mist gas of the breather chamber f flows are installed at two upper and lower positions to show the flow of the oil mist in the breather chamber f (shown by a broken line in FIG. 10). By making it complicated, the flow velocity of the oil mist is drastically reduced and the separation function of oil and gas (gas-liquid separation function) is improved.

(2) Further, in the engine, the weight attached to the crank web cannot completely suppress the inertial force of the piston or the connecting rod, so that vibration occurs. Therefore, some engines have a balancer shaft to suppress the vibration as much as possible. Some of the balancer shafts k are laid out in front of the breather chamber f when viewed from the side of the vehicle body, as shown in FIG.

[0006]

In the engine of the type described above, the bearing (metal bearing) m of the balancer shaft k is fitted in the partition wall d, and lubricating oil is press-fitted between the bearing m and the balancer shaft k. However, the lubricating oil may flow or spout toward the clutch chamber c side. In this case, the lubricating oil that has flowed out or jetted hits the clutch c or the primary driven gear h and scatters, and this lubricating oil flows along the surface of the cover e or the surface of the cover e following the rotation of the clutch or the like. Sometimes you move along. When the openings communicating with the breather chamber f are provided at the upper and lower sides of the breather cover e as in the above-mentioned publication, the lubricating oil flows into the breather chamber f through the opening o1 on the side surface of the breather cover e, which causes high engine rotation. When the amount of oil flowing in is large as in the case of time, there arises a problem that the gas-liquid separation function of the breather chamber deteriorates.

On the other hand, it is conceivable to increase the volume of the breather chamber or to divide the breather chamber into a plurality of chambers in order to prevent deterioration of the gas-liquid separation function of the breather chamber. However, in order to increase the volume, the volume does not fit in the clutch chamber, so that the shape is such that the clutch chamber protrudes to the outside, which causes the breather chamber to protrude to the outside, resulting in an increase in the size of the engine. Further, if the breather chamber is divided into a plurality of chambers, the structure of the breather chamber becomes complicated and the cost becomes high.

The present invention has been made to solve the above-mentioned conventional problems. In an engine in which a balancer shaft is supported near a cover of a breather chamber, the engine is not increased in size and the cost is reduced. Can improve the gas-liquid separation function of the breather chamber without raising the temperature. 4
An object is to provide a breather cover structure for a cycle engine.

[0009]

In order to solve the above-mentioned problems, the invention according to claim 1 is provided with a partition wall for partitioning a transmission chamber and a clutch chamber, which is formed in an engine case, and a partition wall side of the partition wall. In a four-cycle engine having a breather cover that forms a breather chamber together with a partition wall and has an opening, and a balancer shaft that suppresses engine vibration, the balancer shaft has its bearing end facing the periphery of the breather cover. And the balancer shaft side end of the breather cover is formed so as to overlap with the bearing end of the balancer shaft when viewed from the side of the vehicle body.
It has a structure of a breather cover structure of a cycle engine.

[0010]

According to the invention of claim 1, in a four-cycle engine having a balancer shaft for suppressing engine vibration, the balancer shaft is arranged in the partition wall with its bearing end facing the periphery of the breather cover. Even if it is one, the end of the breather cover on the balancer shaft side is formed so as to overlap the bearing end of the balancer shaft when viewed from the side of the vehicle body, so lubrication from the bearing bearing of the balancer shaft (for example, metal bearing) Even when oil is ejected, the end of the breather cover blocks the ejected lubricating oil to prevent the lubricating oil from hitting the clutch or the primary driven gear or reduce the amount of hitting. Therefore, the scattering of lubricating oil in the clutch or the like is completely eliminated or reduced, so that the lubricating oil flowing on the surface of the breather cover is eliminated or reduced, and even if the engine is at high rotation speed, it is drilled on the surface of the breather cover. Lubricant does not enter the breather chamber through the opening. Therefore, the function of the breather room does not deteriorate.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 to 8 are explanatory views of a breather cover structure of a four-cycle engine for a motorcycle according to an embodiment of the present invention. FIG. 1 shows an engine case 10 of an example engine.
FIG. 2 is a side view showing the clutch chamber 14 with the clutch chamber cover removed, FIG. 2 is a plan view of the engine case, FIG. 3 is a sectional view taken along line III-III of FIG.
FIG. 4 is a detailed view of the breather cover, (a) is a side view, (b) is a view from the direction B in (a), and FIG. 5 is an explanation of a state in which the breather cover 34 is assembled to the engine case 10. FIG. 6, FIG. 6 is a detailed view of the end portion of the breather cover 34, FIG. 7 is an operation explanatory view of the breather cover 34, and FIG.

As shown in FIGS. 1 to 3, the engine of the embodiment is a two-cylinder four-cycle engine (cylinders are not shown), and a crankcase and a transmission case are integrated (each crank chamber 14). And mission room 1
8) engine case 10. A starter motor 8 for starting the engine is arranged above the engine case 10. (Engine Case 10) The engine case 10 has an end face 12 located at the front portion in the vehicle traveling direction and on which the cylinder is assembled (the opening 12a that matches the inner circumference of the cylinder).
Crank chamber 14 located inside the case, a clutch chamber 16 located on the right side of the engine case 10 in the vehicle traveling direction, a mission chamber 18 located at the rear of the engine case 10, and a balancer located at the center of the engine. A shaft chamber 19 is provided. Also, the engine case 10
Is a structure that can be separated by a line extending horizontally, and is configured by combining an upper and lower engine case upper 10U and an engine case lower 10L.
An oil pan that holds the lubricating oil is fixed to the lower portion of the engine case lower 10L.

(Crank chamber 14) The crank chamber 14 and the clutch chamber 16 form a lateral portion of the engine case 10 and are partitioned by a first partition wall 10a on the front side on the right side in the vehicle body traveling direction. The mission chamber 18 constitutes a lateral portion and is partitioned by a second partition wall 10b on the right side and the rear side in the vehicle body traveling direction. A crank shaft (not shown) in the crank chamber 14 is rotatably supported at both end portions thereof on a side portion (including the first partition wall 10a) of the engine case 10. The right end of the crankshaft has a first partition wall 1
0a hole 10a1 protrudes into the clutch chamber 16,
A primary drive gear (not shown) is fitted to the protruding end portion.

(Clutch Chamber 16) In the clutch chamber 16, as shown in FIG. 3, a shaft end of a counter shaft (main shaft) 20 for transmitting engine output to each gear 18a arranged in the transmission chamber 18 is provided. The second partition 1
0b of the primary driven gear 2 at the axial end of the counter shaft 20.
2 and the clutch 24 are provided. The primary driven gear 22 meshes with the primary drive gear and is rotatably arranged on the counter shaft 20, and the friction plate, which is the primary side of the clutch 24, is fixed in the rotational direction. Further, the clutch 24 has its secondary side clutch plate fixed in the rotational direction,
The friction plate is pressed against and released from the clutch plate to disconnect and connect the clutch 24.

The clutch chamber 16 includes a wall portion (clutch chamber wall portion) 16a formed around the shafts of the primary drive gear and the clutch 24 and protruding to the right side portion of the engine case 10, and the primary drive gear. And a clutch chamber cover 16b which covers the clutch 24 and is superposed on the clutch chamber wall portion 16a. The clutch chamber wall portion 16a and the clutch chamber cover 16
Both mating surfaces with b are flat, and a gasket is interposed therebetween. That is, the clutch chamber wall 16a
And the clutch chamber cover 16b and further the engine case 10
The clutch chamber 16 is formed by being surrounded by the first wall portion 10a and the second wall portion 10b at the side portions of the.

(Mission Room 18) The Mission Room 1
Gears 18a corresponding to various gears are arranged in the drive gear 8, and a drive shaft (not shown) for transmitting the engine output input by the counter shaft 20 and changed by the gears 18a to the rear wheel drive chain. ) Is provided. Similar to the counter shaft 20, this drive shaft is axially supported on both sides of the engine case 10, and an opening 10b2 is formed in the second wall 10b for axially supporting the drive shaft end. Roller bearings can be used for the shaft supporting portions of the counter shaft 20 and the drive shaft.

(Balancer Shaft Chamber 19) The balancer shaft chamber 19 is provided with a balancer shaft 28 for canceling engine vibration due to vertical movement of the piston that cannot be canceled by the crank web. The shaft end of the balancer shaft 28 is rotatably supported on both sides of the engine case 10, and the clutch side shaft end of the balancer shaft 28 is the clutch chamber 1.
We are facing 6. The clutch-side shaft end is a partition wall of the engine case 10, and includes first and second partition walls 10a.
And 10b are rotatably supported by an opening 10c1 formed in the partition wall 10c at the center and in the upper portion. In addition,
The shaft bearing of the balancer shaft 28 on the partition wall 10c is performed by a metal bearing 28a.

(Breather chamber 36) The mission chamber 18
The second partition wall 10b that separates the clutch chamber 16 from the clutch chamber 16 is shown in FIG.
As shown in FIG. 3, the openings 10b1 and 1b for supporting the counter shaft 20 and the drive shaft, respectively.
A bulged portion 30 is formed above 0b2 so as to extend to the upper portion of the mission chamber 18. This bulge 3
0 is concave when viewed from the clutch chamber side. The bulging portion 30 bulges up to the vicinity of the starter motor 8 in the upper portion of the mission chamber 18 of the engine case 10 and has a sufficient internal volume when viewed from the clutch chamber 16 side. Further, a breather cover 34 is attached to the opening 32 on the clutch chamber 16 side of the bulged portion 30 so as to cover it from the clutch chamber 16 side. In this state, the breather portion 30 and the breather cover 34 close the bulged portion 30. The breather chamber 36 is formed in the space.
A pipe (for example, a union pipe) 38 facing vertically upward is provided above the bulged portion 30, and the breather chamber 36 communicates with the outside through the pipe 38. Further, a gasket (indicated by reference numeral 34a in FIG. 8) may be interposed between the breather cover 34 and the opening 32 to improve airtightness.

(Breather Cover 34) The breather cover 34 is attached to the engine case 10 as shown in FIG.
7 or as shown in FIG. 7, and the breather cover 34 itself is shown in detail in FIG.
((A): side view, (b): bottom view). As shown in FIGS. 1 and 4, the breather cover 34 is
The entire shape is an arc shape of about 1/4 circle, and is arranged on the concentric circle of the counter shaft 20 in a state of being arranged so as to cover the opening 32 of the bulged portion 30 (a state of forming the breather chamber 36). It is arranged along. Further, in the substantially central portion of the breather cover 34,
A circular through hole 40 is formed, and the through hole 40 is for communicating the breather chamber 36 and the clutch chamber 16. In addition, bolt holes 42 are formed at appropriate positions on the rear end portion and the front end portion, and the bolt holes 42 are formed corresponding to the boss portions 44 projecting from the engine case 10 in the crank chamber 16.

Further, the front end portion 46 of the breather cover 34 in the attached state extends so as to overlap a part or the whole of the shaft end portion of the balancer shaft 28 (which can have a size as necessary) when viewed from the side of the vehicle body. Formed into a plate shape. The front end portion 46 of the breather cover 34 can have various sizes or shapes. That is,
As shown in FIG. 5, for example, the front end portion 46 has the balancer shaft 28 in the mounted state in a side view of the vehicle body.
10c1 into which the end of the
The length that covers approximately 1/5 of the diameter from the outer peripheral edge of the solid line (solid line 46a
, Or a length (shown by a broken line 46b) that covers the entire length. Also, the front end portion 46
For example, as shown in FIG. 6A, it may be formed in a flat plate shape extending along the front-rear direction of the vehicle, or as shown in FIG. 6B, it may be bent so as to approach the opening 10c1. it can. The lower part of the breather cover 34 is shown in FIG.
As shown in FIG. 5, a stepped portion having a release portion 48 for releasing the breather chamber 36 in an attached state and having a shape corresponding to the clutch 24 and the primary driven gear 22 so as not to interfere with the clutch 24 and the primary driven gear 22. 50 is formed corresponding to the counter shaft 28.

Next, the operation of the embodiment will be described. In the engine of the embodiment, the lubricating oil is pumped to each part when the engine is operating. The lubricating oil press-fitted into the bearing metal 28a of the balancer shaft 28 is ejected from the end of the bearing metal 28a. In the breather cover structure of the embodiment, as shown in FIGS. 7 and 8,
Since the front end portion of the breather cover 34 overlaps the balancer shaft end portion in a side view, the lubricating oil press-fitted into the bearing metal 28a is ejected from the bearing metal 28a, while the balancer shaft 28 of the breather cover front end portion 46 is ejected. Since the jetted lubricating oil hits and falls to the side, the amount of lubricating oil that hits the clutch 24 or the primary driven gear 22 and scatters decreases, and the amount of oil mist decreases. Further, the lubricating oil that comes out of the bearing metal 28a and tries to flow along the side surface of the breather cover 34 is blocked by the front end portion 46, so that the amount of the lubricating oil disappears or decreases.

Therefore, the lubricating oil that tries to flow into the breather chamber 36 from the through hole 40 along the flow of the breather gas from the clutch chamber 16 is significantly reduced, and the amount of the lubricating oil in the breather chamber 36 is reduced, so that the breather chamber 36 is reduced. It is possible to prevent the gas-liquid separation function of 36 from being deteriorated. Therefore, according to the embodiment, since the invasion of the lubricating oil into the breather chamber 36 is reduced, the gas-liquid separation function of the oil is good even at the high engine speed, and the oil consumption is good.
That is, the gas-liquid separation function of the breather chamber 36 is good. Further, since the gas-liquid separation function of the breather chamber 36 can be improved simply by extending the front end portion 46 of the breather cover 34, the structure is simple and the cost is low. Further, in order to maintain the function of the breather chamber 36, the internal volume 36 of the breather chamber 36
Since the engine does not need to be large, the engine becomes compact.

In the above embodiment, the present invention is applied to the engine of a motorcycle, and the present invention is suitable for a motorcycle for which miniaturization is highly demanded, but the scope of the present invention is The present invention is not limited to this, and can be applied to various other devices as long as the device uses an engine as another vehicle or another prime mover. Further, in the above embodiment,
The extended part of the breather cover is the front end of the breather cover.This is because the end of the balancer shaft is located in front of the breather cover, and the other direction corresponds to the position of the balancer shaft. It is also within the scope of the invention to extend the end of the breather cover.

[0024]

As described above, according to the present invention, in an engine in which the balancer shaft is supported in the vicinity of the breather cover of the breather chamber, the spray of lubricating oil is blocked at the end of the breather cover, and the lubricating oil is blocked. Since the invasion of the oil into the breather chamber is reduced, the gas-liquid separation function of oil is good even at high engine speed, and the oil consumption is good. That is, the breather has a good gas-liquid separation function. Further, since the gas-liquid separation function of the breather chamber can be improved simply by extending the front end portion of the breather cover, the gas-liquid separation function can be enhanced with a simple structure at low cost. Further, since it is not necessary to increase the internal volume of the breather chamber in order to maintain the function of the breather chamber, the gas-liquid separation function can be enhanced in a small engine state.

[Brief description of drawings]

FIG. 1 is an explanatory view of a breather cover structure of a four-cycle engine for a motorcycle according to an embodiment of the present invention, a side view showing a clutch chamber 14 with an engine case of the engine having a clutch chamber cover removed. Is.

FIG. 2 is a plan view of the engine case of FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG. 2 showing the breather chamber.

4A and 4B are detailed views of the breather cover, in which FIG. 4A is a side view and FIG. 4B is a view from the direction B in FIG.

FIG. 5 is an explanatory view showing a state in which the breather cover is assembled to the engine case.

FIG. 6 is a detailed view of the front end portion of the breather cover.

FIG. 7 is an explanatory view of the operation of the breather cover.

FIG. 8 is an explanatory view of the operation of the breather cover.

FIG. 9 is an explanatory diagram of an example of a conventional breather structure.

FIG. 10 is an explanatory diagram of another example of the conventional breather structure.

[Explanation of symbols]

 10 Engine Case 10a 1st Partition Wall 10b 2nd Partition Wall 14 Crank Chamber 18 Mission Chamber (Transmission Room) 19 Balancer Shaft Chamber 20 Counter Shaft 24 Clutch 26 Clutch Cover 28 Balancer Shaft 28a Balancer Shaft Metal Bearing 30 Inflated Part 34 Breather Cover 36 Breather chamber 40 Through hole 46 Breather cover front end

Claims (1)

[Claims] 1. A partition wall for partitioning a transmission chamber and a clutch chamber formed in an engine case, and a breather cover arranged on the clutch chamber side of the partition wall to form a breather chamber together with the partition wall and having an opening. In a four-cycle engine having a balancer shaft that suppresses engine vibration, the balancer shaft is arranged in the partition wall with its bearing end facing the periphery of the breather cover, and the balancer shaft has A breather cover structure for a four-cycle engine, wherein an end portion on the balancer shaft side is formed so as to overlap with a bearing end portion of the balancer shaft.