JP3077495B2 - Breather cover structure for 4-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 cover structure for a four-cycle engine, which separates oil mixed with blow-by gas, returns the oil to an oil pan, and discharges the original blow-by gas to the outside of the engine. It relates to a 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. The engine case is filled with lubricating oil for smooth operation of the above-mentioned crankshaft and the like. When the engine is running, this lubricating oil is vigorously stirred by the crankshaft and the like to form a mist 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 in the engine case constantly fluctuates as the piston moves up and down. Therefore, when the engine case is closed, 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 of the engine case to the outside.

However, since the above-mentioned oil mist gas is filled in the engine case, when a breather hole is formed in the engine case, the oil mist gas blows out from the breather hole to reduce oil deficiency. May be invited. Therefore, conventionally, a breather chamber with a breather hole formed at the end of a maze-shaped room is provided in the engine case, and the distance and volume from when oil mist gas enters this breather chamber to escape to the outside is increased. Means are adopted to separate the oil component from the gas component, return the oil component to the engine case, and discharge only the gas component to the outside.

(1) In the breather chamber as described above, the larger the volume of the breather chamber, the greater the effect of separating oil and gas. In engines that require compactness, such as motorcycle engines, 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 and 10, a partition wall d between a transmission chamber b and a clutch chamber c of an engine case a is provided.
A breather cover e is attached from the clutch chamber c side to a chamber partitioned by the breather cover e and the partition wall d to form a breather chamber f (see JP-A-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 driving gear i. Reference numeral j denotes a breather pipe that opens the breather chamber to the outside. In the above-mentioned publication, openings (discharge ports) o1 and o2 into which the oil mist gas of the breather chamber f flows are installed at two upper and lower locations to control the flow of the oil mist in the breather chamber f (shown by broken lines in FIG. 10). By making it complicated, the flow rate of the oil mist is greatly reduced to improve the oil-gas separation function (gas-liquid separation function).

(2) Further, in the engine, vibration occurs because the inertia force of the piston or the connecting rod cannot be completely suppressed only by the weight attached to the crank web. Therefore, some engines are provided with a balancer shaft to suppress the vibration as much as possible. As shown in FIG. 10, 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.

[0006]

In an engine of the type described above, a bearing (metal bearing) m of the balancer shaft k is fitted into the partition wall d, and lubricating oil is press-fitted between the bearing m and the balancer shaft k. As a result, the lubricating oil may flow or spill to the clutch chamber c side. In this case, the lubricating oil that has flowed or spouted hits the clutch c or the primary driven gear h and scatters, and the lubricating oil flows on the surface of the cover e or rotates along with the rotation of the clutch or the like. Sometimes it moves along. When the openings communicating with the breather chamber f are provided on the upper and lower sides of the breather cover e as described in the above publication, the lubricating oil flows into the breather chamber f from the opening o1 on the side of the breather cover e, and the engine rotates at a high speed. 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 is reduced.

On the other hand, it is conceivable to increase the volume of the breather chamber or divide the breather chamber into a plurality of chambers in order to prevent the gas-liquid separation function of the breather chamber from lowering. However, in order to increase the volume, it cannot be accommodated in the clutch chamber, so that it has a shape protruding from the clutch chamber to the outside, so that the breather chamber protrudes to the outside and the engine becomes large. Further, since the breather chamber is divided into a plurality of chambers, the configuration of the breather chamber becomes complicated, and the cost becomes high.

SUMMARY OF THE INVENTION 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 cost is reduced. Can improve the gas-liquid separation function of the breather chamber without increasing the pressure 4
It is an object to provide a breather cover structure for a cycle engine.

[0009]

According to a first aspect of the present invention, there is provided a partition wall for partitioning a transmission chamber and a clutch chamber formed in an engine case, the partition wall being disposed on the clutch chamber side of the partition wall. In a four-stroke engine including a breather cover forming a breather chamber together with a partition wall and having an opening formed therein, and a balancer shaft for suppressing engine vibration, the balancer shaft has a bearing end facing the periphery of the breather cover. Wherein 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.
The cycle engine has a breather cover structure.

[0010]

According to the first aspect of the present invention, in a four-stroke engine having a balancer shaft for suppressing engine vibration, the balancer shaft has its bearing end disposed on the partition wall facing the periphery of the breather cover. However, since 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, lubrication from the bearing bearings (eg, metal bearings) of the balancer shaft is achieved. Even when the oil is jetted, the end of the breather cover blocks the jetted lubricating oil so that the lubricating oil does not hit the clutch or the primary driven gear or reduces the amount of the hit. Therefore, the scattering of the lubricating oil in the clutch or the like is completely eliminated or reduced.Therefore, there is no or reduced lubricating oil flowing on the breather cover surface. Lubricating oil does not enter the breather chamber through the opening. Therefore, the function of the breather chamber does not deteriorate.

[0011]

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

As shown in FIGS. 1 to 3, the engine of the embodiment is a two-cylinder four-stroke engine (cylinders are not shown), and a crankcase and a transmission case are integrated (each a crankcase 14). And mission room 1
8) of the engine case. A starter motor 8 for starting the engine is arranged in an upper portion of the engine case 10. (Engine Case 10) The engine case 10 has an end surface 12 (an opening 12a coinciding with the inner circumference of the cylinder) which is located at a front part in the vehicle traveling direction and on which the cylinder is mounted.
, A clutch chamber 16 located on the right side of the engine case 10 in the vehicle traveling direction, a transmission 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 horizontal line, and is configured by combining an upper and lower engine case upper 10U and an engine case lower 10L.
An oil pan for retaining lubricating oil is fixed to a lower portion of the lower engine case 10L.

(Crank Chamber 14) The crank chamber 14 and the clutch chamber 16 constitute a side portion of the engine case 10 and are separated by a first partition wall 10a on the right and front in the vehicle body traveling direction. And the transmission chamber 18 constitute side portions and are partitioned by a second partition wall 10b on the right and rear in the vehicle body traveling direction. A crankshaft (not shown) in the crank chamber 14 is rotatably supported at both ends by a lateral portion (including the first partition 10a) of the engine case 10. The right end of the crankshaft is the first partition 1
0a projecting into the clutch chamber 16 from the hole 10a1;
A primary drive gear (not shown) is fitted to the protruding end.

(Clutch Chamber 16) As shown in FIG. 3, the clutch chamber 16 has a shaft end of a counter shaft (main shaft) 20 for transmitting engine output to each gear 18a disposed in the transmission chamber 18. The part is the second partition 1
0b, and protrudes from an opening 10b1 of the counter shaft 20b.
2 and a clutch 24 are provided. The primary driven gear 22 meshes with the primary drive gear and is rotatably disposed on the countershaft 20, and a friction plate, which is the primary side of the clutch 24, is fixed in the rotation direction. Further, the clutch 24 has a clutch plate as a secondary side thereof fixed in the rotational direction,
The clutch 24 is disengaged or connected by pressing and releasing the friction plate against the clutch plate.

The clutch chamber 16 includes a wall (clutch chamber wall) 16a surrounding the primary drive gear and the shaft of the clutch 24 and protruding from the right side of the engine case 10; And a clutch chamber cover 16b which covers the clutch 24 and overlaps the clutch chamber wall 16a. The clutch chamber wall 16a and the clutch chamber cover 16
The two 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 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 on the side of the first wall portion 10a.

(Mission Chamber 18) The Mission Chamber 1
A gear 18a corresponding to various speeds is disposed in the drive shaft 8, and a drive shaft (not shown) that transmits an engine output that has been input by the countershaft 20 and has been shifted by the gear 18a to a rear wheel drive chain. ) Are arranged. The drive shaft is supported on both sides of the engine case 10 similarly to the countershaft 20, and an opening 10b2 is formed in the second wall 10b to support the end of the drive shaft. Roller bearings can be used for the shaft 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 the engine vibration caused by the 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 of the engine case 10, and includes first and second partition 10a.
And 10b are rotatably supported by an opening 10c1 formed in a partition 10c substantially at the center and above. In addition,
The support of the balancer shaft 28 in the partition 10c is performed by a metal bearing 28a.

(Breather chamber 36) The mission chamber 18
The second partition 10b that separates the clutch chamber 16 from
As shown in FIG. 3, respective openings 10b1 and 1b for pivotally supporting the counter shaft 20 and the drive shaft are provided.
Above 0b2, a bulged portion 30 is formed to extend to the upper part of the mission chamber 18. This swollen part 3
0 is concave when viewed from the clutch chamber side. The bulged portion 30 is bulged to the vicinity of the starter motor 8 in the upper portion of the transmission 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 expanded portion 30 so as to cover the opening 32 from the clutch chamber 16 side. In this state, the breather cover 34 is closed by the expanded portion 30 and the breather cover 34. The breather chamber 36 is constituted by the space in which the breathing is performed.
In addition, a pipe (for example, a union pipe) 38 which is directed vertically upward is provided above the bulging portion 30, and the breather chamber 36 communicates with the outside via 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.

(Breazer Cover 34) The state of the breather cover 34 attached to the engine case 10 is shown in FIG.
As shown by a dashed line in FIG. 7, or as shown in FIG. 7, 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
The whole shape has an arc shape of approximately 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 bulging portion 30 (a state of forming the breather chamber 36). It is arranged along. In addition, approximately in the center of the breather cover 34,
A circular through hole 40 is formed, and this 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 and the front end, and the bolt holes 42 are formed in the crank chamber 16 corresponding to the bosses 44 projecting from the engine case 10.

The front end 46 of the breather cover 34 in an attached state extends so as to overlap a part or the entirety of the shaft end of the balancer shaft 28 (which can be sized as required) when viewed from the side of the vehicle body. It is formed in a plate shape. The front end 46 of the breather cover 34 can be of various sizes or shapes. That is,
As shown in FIG. 5, for example, the front end portion 46 of the balancer shaft 28 in the mounted state when viewed from the side of the vehicle body.
Of the opening 10c1 into which the end of the
Length that covers approximately 1/5 of the diameter from the outer peripheral end of the
) Or a length that covers the whole (shown by a broken line 46b). Also, the front end 46
6A may be formed in a flat plate shape extending along the front-rear direction of the vehicle, for example, as shown in FIG. 6A, or may be bent so as to approach the opening 10c1, as shown in FIG. it can. The lower part of the breather cover 34 is shown in FIG.
Has a release portion 48 for releasing the breather chamber 36 in the mounted state, and has a stepped portion 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, lubricating oil is pumped to each part during engine operation. The lubricating oil press-fitted into the bearing metal 28a of the balancer shaft 28 gushes from the end of the bearing metal 28a. In the breather cover structure of the embodiment, as shown in FIG. 7 and FIG.
Since the front end of the breather cover 34 overlaps with the end of the balancer shaft in a side view, the lubricating oil press-fitted into the bearing metal 28a gushes from the bearing metal 28a, while the balancer shaft 28 of the breather cover front end 46 is opposed to the lubricating oil. Since the jetted lubricating oil falls on the side, the amount of the lubricating oil scattered on the clutch 24 or the primary driven gear 22 is reduced, and the amount of oil mist is reduced. Further, since the lubricating oil coming out of the bearing metal 28a and flowing along the side surface of the breather cover 34 is blocked by the front end portion 46, the amount of the lubricating oil is reduced or reduced.

Accordingly, the amount of lubricating oil flowing 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 lubricating oil in the breather chamber 36 is reduced. 36 can be prevented from being deteriorated. Therefore, according to the embodiment, since the intrusion of the lubricating oil into the breather chamber 36 is reduced, the function of separating the gas and liquid of the oil is good even at a 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 only by extending the front end portion 46 of the breather cover 34, the cost is low with a simple structure. In order to maintain the function of the breather chamber 36,
Because it is not necessary to increase the size, the engine becomes compact.

In the above embodiment, the present invention is applied to a motorcycle engine, and the present invention is suitable for a motorcycle which is required to be downsized. However, the scope of the present invention is as follows. The present invention is not limited to this, and can be applied to other various devices as long as they use an engine as another vehicle or another motor. In the above embodiment,
The extended portion of the breather cover is the front end of the breather cover, because the end of the balancer shaft is located in front of the breather cover, and in the other direction corresponding to the position of the balancer shaft. Extending the end of the breather cover is also within the scope of the present invention.

[0024]

As described above, according to the present invention, in an engine in which a balancer shaft is supported near a breather cover in a breather chamber, splash of lubricating oil is blocked at the end of the breather cover, and Therefore, even if the engine rotates at a high speed, the oil-gas separation function is good, and the oil consumption is good. That is, the gas-liquid separation function of the breather is good. Further, the gas-liquid separation function of the breather chamber can be improved simply by extending the front end of the breather cover. Therefore, 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.

[Brief description of the drawings]

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

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

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

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

FIG. 5 is an explanatory diagram of a state where a breather cover is assembled to an engine case.

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

FIG. 7 is an explanatory diagram of an operation of a breather cover.

FIG. 8 is an operation explanatory view of a 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]

 DESCRIPTION OF SYMBOLS 10 Engine case 10a 1st partition 10b 2nd partition 14 Crank chamber 18 Transmission chamber (transmission chamber) 19 Balancer shaft chamber 20 Counter shaft 24 Clutch 26 Clutch cover 28 Balancer shaft 28a Metal bearing of balancer shaft 30 Inflated part 34 Breather Cover 36 Breather chamber 40 Through hole 46 Breather cover front end

Claims (1)

(57) [Claims] 1. A partition formed in an engine case and separating a transmission chamber and a clutch chamber, a breather cover disposed on the clutch chamber side of the partition and forming a breather chamber with the partition and having an opening formed therein. A balancer shaft for suppressing vibration of the engine, wherein the balancer shaft has a bearing end disposed on a partition wall facing the periphery of the breather cover, and the balancer shaft is provided with the balancer shaft when viewed from the side of the vehicle body. A breather cover structure for a four-stroke engine, wherein an end on the balancer shaft side is formed so as to overlap a bearing end of the balancer shaft.