JP2822004B2 - Breather device 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 structure of a breather device for a four-cycle engine.

[0002]

2. Description of the Related Art In a four-stroke cycle engine, oil (lubricating oil) in a crankcase or a transmission case communicating with the crankcase due to a pressure increase in the crankcase caused by blow-by gas leaking from a combustion chamber into the crankcase. A breather device (breathing device) is provided to prevent the gas from leaking out of the bearing portion or the like.

The oil in the engine case (whole or part of the crankcase, transmission case, clutch case, etc.) is in the form of a mist mixed with air, and the breather device prevents the oil itself from leaking. Alternatively, from the viewpoint of suppression, a maze plate or rib provided with a blow-by gas containing oil mist is provided, and a functional structure for collecting oil mist by attaching oil to the maze plate or the like, that is, suitable for gas-liquid separation Has a simple structure. Prior art documents that disclose such a breather device include, for example, Japanese Utility Model Publication No. 63-37463.

[0004]

However, in the conventional breather device of a four-stroke engine, a breather chamber formed at a desired position of an engine case has a partition member having a gas-liquid separation function such as a punching plate or a wire mesh, that is, a partition member. Special parts for separating oil mist from gas are required, and the number of parts increases,
It may be difficult to make the engine compact. Further, in the case of manufacturing by a mold, the mold becomes complicated and the cost increases.

SUMMARY OF THE INVENTION The present invention has been made in view of such prior art, and it is an object of the present invention to provide an oil mist separation function and a gas supply function using a gasket attached to a mating surface of a cover forming a breather chamber. By forming a maze for gas distribution having a circulation function, an extra space is not required, and without increasing the size of the engine, a four-cycle engine capable of exhibiting a sufficient breather effect and an oil mist separation and collection function can be provided. The purpose is to provide a breather device.

[0006]

In order to achieve the above object, a breather device for a four-stroke engine according to the present invention has an engine case formed with an open upper surface communicating with the inside of the engine case, and a guide on an upper surface of the concave portion. By fixing a cover having an outlet via a gasket, a breather chamber is formed by the concave portion and the cover, and a punched bent portion is formed in the gasket so as to abut a raised portion in the concave portion. It is characterized in that a maze for gas distribution composed of a bypass having an oil mist separation function and a gas distribution function is formed.

[0007]

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view in the front-rear direction of one embodiment of a breather device of a four-cycle engine to which the present invention is applied, and FIG. 2 is a longitudinal sectional view in the left-right direction along line 2-2 in FIG. FIG. 3 is a partial rear view as viewed from line 3-3 in FIG. 1 and 2, the four-stroke engine is:
An engine case 3 having a crankcase 1 and a transmission case 2 communicating with each other, a cylinder 4,
It comprises a cylinder head 5 and a cylinder head cover 6. A carburetor 7 is connected to an intake hole of the cylinder head 5, and an air cleaner 8 is connected to a suction side of the carburetor 7.

Air is sucked from the air cleaner 8 by utilizing the negative pressure of the intake air, and a mixture such as gasoline is mixed with the air by the carburetor 7 to prepare a mixture. The crankshaft 9 is supplied (supplied) to an expansion / compression chamber (combustion chamber), and the mixture is ignited to explode and expand, thereby rotating the crankshaft 9 and obtaining an output by the torque of the crankshaft 9. I have.

Referring to FIGS. 1 and 2, a generator 10 is provided above the transmission case 2 of the engine case 3.
The storage chamber 11 for hermetically protecting the drive mechanism is integrally formed. The storage chamber 11 communicates with the interior of the transmission case 2 (engine case 3) through a through hole 12 formed in the bottom. The through holes 12 are formed at four places in this embodiment. The generator 10 is fixed to the open end face side (the left side in FIG. 2) of the storage chamber 11 by bolts or the like in a sealed state.

On the other hand, on the upper part of the transmission case 2,
A drive shaft 13 for driving the generator 10 is rotatably supported by bearings 14 and 15. A sprocket 16 is fixed to the drive shaft 13. The drive shaft 13 is driven by the chain 17 and the sprocket 16 in synchronization with the rotation of the crankshaft 9.
Is rotationally driven by a driving mechanism including When the generator 10 is mounted, the shaft 18 is connected to the drive shaft 13.
Is engaged with the rotational force transmission state. Therefore, the generator 10 is driven in synchronization with the operation of the engine (the rotation of the crankshaft 9).

In FIG. 1 and FIG.
A primary breather chamber (primary chamber) of the breather device according to the present embodiment is configured, and a secondary breather chamber (secondary chamber) 20 is configured above the storage chamber 11. The secondary chamber 20 is defined by an inner surface of a concave portion 21 having an open upper end surface formed above the storage chamber 11 of the engine case 3 and an inner surface of a cover 22 tightly fixed to the upper end surface of the concave portion 21. ing. A gasket 23 for sealing is mounted between the recess 21 and the mating surface (joining surface) of the cover 22 in a press-contact state.

The secondary breather chamber 20 communicates with the primary breather chamber (storage chamber) 11 through a through hole 24. The cover 22 constituting the secondary chamber 20 is provided with an outlet (communication port) 25 for communicating the inside of the secondary chamber 20 with, for example, an air cleaner (not shown). The outlet 25 is normally connected to the inside of the air cleaner or the intake system, but may be connected to the atmosphere or the outside depending on the case. The engine case 3 includes the secondary chamber 2.
A return passage 26 (FIG. 1) communicating from the bottom of the engine case 3 to the bottom of the engine case 3 is formed. The outlet 25
Is an opening for discharging the blow-by gas from which the oil mist has been separated into the interior of the air cleaner, and the return passage 26 is a passage for collecting the oil separated from the blow-by gas into the engine case 3.

FIG. 4 is a perspective view of the gasket 23 in FIG. 1, FIG. 5 is a plan view of the gasket 23 in FIG. 4, and FIG. 6 is a cross-sectional view taken along line 6-6 in FIG. . 4 to 6, the gasket 23 is formed of a single sheet-shaped (or flat) sealing material. Then, in addition to the peripheral seal portion 27 having the original function of the gasket, a part (approximately half in the illustrated example) of the inner portion is punched out from the peripheral seal portion 27 and bent to form a partition wall portion. 28, an opening 29, and a bent wall 30 are formed.

In this case, the partition wall portion 28 formed in the inner region of the peripheral seal portion 27 is slightly larger than the peripheral seal portion 27 (for example, about 0.5 mm
It is formed into a tapered surface that is extruded downward and slightly, but becomes lower as it approaches the opening 29. According to the partition wall portion 28, the oil separated by the partition wall portion 28 can be easily collected from the opening 29.

1 and 2, when the gasket 23 is mounted in the secondary breather chamber 20, the distal end of the bent wall portion 30 of the gasket 23 has a raised portion formed in the recess 21 of the engine case 3. And a blow-by gas passage (or opening) 32, 32 on both sides of the bent wall portion 30.
(FIG. 1) is formed. Therefore, in the present embodiment, the secondary breather chamber 20 is partitioned by the gasket 23 into a lower chamber (recessed chamber) 33 and an upper chamber (cover chamber) 34, and the lower chamber 33 and the upper chamber 34 are formed by the bent wall. The openings 32, 32 on both sides of the portion 30 and the opening 29 communicate with each other.

As the material of the gasket 23, various materials and structures can be used. For example, by forming a soft layer such as foamed rubber integrally on both sides of a metal elastic plate such as a stainless steel plate. Those having improved sealing function and oil separating function are used. A maze configuration excellent in breather function for separating the oil mist in the blow-by gas from the crankcase portion 1 and discharging the blow-by gas after the oil separation,
This is realized by the primary breather chamber 11 housing the drive mechanism of the auxiliary machine such as the generator 10 and the secondary breather chamber in which the gasket 23 forming the above-described detour is mounted.

That is, the blow-by gas leaked from the combustion chamber of the engine into the crankcase 1 contains oil mist while passing through the crankcase portion 1 and the transmission case portion 2. Through the primary breather chamber (accessory drive mechanism storage chamber) 1
1 and some oil mist is separated in the primary breather chamber 11. The separated oil is collected into the engine case 3 through the through hole 12.

Next, the blow-by gas in the primary breather chamber 11 is passed through the through-hole 24 to the secondary breather chamber 2.
0, and the partition wall 28 of the gasket 23
And collides with the bent wall 30, bypasses the openings 32, 32 on both sides of the bent wall 30,
The oil mist is further separated while flowing into the upper chamber (cover chamber) 34 and changing direction. The blow-by gas from which the oil has been separated in this way is discharged from the outlet (communication port) 25. The discharge destination from the outlet 25 is selected, for example, to the clean side of the air cleaner, the intake passage, the outside air (atmosphere), and the like.

According to the embodiment described above, the gasket 23 for mounting the cover 22 forming the breather chamber (secondary chamber) 20 on the upper part of the engine case 3 is used, and the gasket 23 is stamped and bent on the gasket 23 itself. By forming the above, the function of separating the oil mist of the blow-by gas and the function of distributing the gas can be provided, so that a breather chamber excellent in function can be formed with an extremely simple configuration having a small number of parts.

Further, the tip of the embossed bent portion (bent wall portion) 30 formed on the gasket 23 itself is brought into elastic contact with the stepped portion (raised portion) 31 on the engine case 3 side, so that gas flow in the central portion can be achieved. Since the gas passages 32 are formed on both sides while being shut off, the oil mist separating function and the breather function can be improved only by forming the gasket 23 itself. further,
By using a gasket 23 having a structure in which soft layers of foamed rubber or the like are integrally formed on both sides of a metal elastic plate such as a stainless steel thin plate, both the sealing function and the oil separating function can be improved. .

The blow-by gas is supplied to the engine case 3
Since it enters the secondary chamber (breather chamber) 20 through the existing generator drive mechanism accommodating chamber 11 provided at the upper part of the air conditioner, there is no need to form an extra expansion chamber. The gas pressure in the next chamber 20 can be suppressed to a low value, and the breather effect can be improved. In addition, since the breather device is disposed by utilizing the space between the upper portion of the engine case 3 and the carburetor 7, the previously wasted space can be effectively utilized,
The engine can be made compact without sacrificing design flexibility.

In the above embodiment, the case where the primary breather chamber 11 is a driving mechanism storage chamber for a generator is illustrated, but it may be a driving mechanism storage chamber for another auxiliary machine such as a starter motor. That is, any auxiliary equipment can be used.

[0024]

As is apparent from the above description, according to the first aspect of the present invention, a cover having an open top surface communicating with the inside of the engine case is formed in the engine case, and an outlet is provided on the upper surface of the recess. Is fixed by a gasket to form a breather chamber with the concave portion and the cover, and the gasket is formed with a punched bent portion that comes into contact with a raised portion in the concave portion, so that a blow-by gas oil mist separating function is formed. And a maze for gas distribution consisting of a detour having a gas distribution function, so that it has an oil mist separation function and a gas distribution function utilizing the shape of the gasket itself mounted on the mating surface of the cover. By forming a maze for gas distribution,
A breather device for a four-stroke engine that can exhibit a sufficient breather effect and an oil mist separation and collection function without requiring an extra space and without increasing the size of the engine is provided.

[0025]

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a breather device of a four-cycle engine to which the present invention is applied.

FIG. 2 is a left-right vertical sectional view taken along line 2-2 in FIG.

FIG. 3 is a partial rear view as viewed from a line 3-3 in FIG. 1;

FIG. 4 is a perspective view of the gasket in FIG.

FIG. 5 is a plan view of the gasket of FIG.

FIG. 6 is a sectional view taken along lines 6-6 in FIG. 5;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Crankcase part 2 Transmission case part 3 Engine case 4 Cylinder 5 Cylinder head 7 Vaporizer 9 Crankshaft 10 Auxiliary machine (generator) 11 Primary room (Primary breather room = drive mechanism storage room) 12 Through hole 13 Drive shaft 20 2 Next chamber (secondary breather chamber) 21 Concave part 22 Cover 23 Gasket 24 Through hole 25 Outlet (communication port) 26 Return path 27 Peripheral seal part 28 Partition wall part 29 Opening part 30 Bend wall part 31 Ridge part (Stepped part) 32 blow-by gas passage (opening) 33 lower chamber (recess chamber) 34 upper chamber (cover chamber)

Claims (1)

(57) [Claims] 1. A breather having an upper surface open to communicate with the inside of the engine case is formed in the engine case, and a cover having an outlet on the upper surface of the recess is fixed via a gasket. By forming a chamber and forming a bent portion in the gasket in contact with a raised portion in the concave portion, a maze for gas distribution including a bypass having an oil mist separating function and a gas flowing function of blow-by gas is formed. A breather device for a four-stroke engine.