JP2000145555A - Positive crankcase ventilation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate drain lines from positive crankcase ventilation. SOLUTION: A return passage extending from the breather chamber of an engine is connected at one end to a joint part 50 at the lower end of a return chamber 36. The return chamber 36 is integrated with the interior of a clean side 43 in an air cleaner case body 40 so as to connect to the clean side 43 via a communication hole 51 formed in the top of a return chamber cover 46. An inflected passage 54 including ribs 53 is defined between the joint part 50 and the communication hole 51 to offer a vapor-liquid separation section where blowby gas is filtered to give gas contents, which is fed into the clean side 43 via the communication hole 51, and water contents, which is urged to flow back into the joint part 50 or into the return passage that returns it to the crankcase breather chamber. This system requires no drain lines and only simple pipe arrangement to thus reduce the number of components used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow-by gas reducing apparatus for an internal combustion engine of a motorcycle or the like, which has a simplified structure and enables cost reduction.

[0002]

2. Description of the Related Art Japanese Utility Model Publication No. Sho 56-24258 discloses that a blow-by gas reducing chamber is formed integrally with a long passage from the top wall to the back wall of an air cleaner case. 1 shows a blow-by gas reducing device which communicates with a blow-by gas generating portion of an engine through a reducing passage and has a lower end connected to a drain tube. The blow-by gas introduced into the apparatus is separated into gas and liquid while flowing from the upper part to the lower part, and the gaseous component is supplied to the vicinity of the inlet of the con tube through a guide pipe mounted inside the top wall of the air cleaner case. , And is sent to the vaporizer together with the clean air in the clean side.

[0003]

By the way, even if the reducing chamber is formed integrally with the air cleaner case as described above, the piping for the reducing passage and the piping for the drain are required, and the piping structure is relatively complicated. Therefore, simplification of the piping structure is desired. Also, it is desirable that the blow-by gas be supplied to the vicinity of the inlet of the con tube as much as possible so as not to adhere to the filter to cause clogging. Also in this respect, the number of parts increases. Accordingly, an object of the present invention is to solve such a problem and to provide a blow-by gas reducing apparatus that can simplify the structure and reduce the number of parts.

[0004]

In order to solve the above-mentioned problems, a blow-by gas reducing device for an internal combustion engine for reducing blow-by gas from an engine to a clean side of an air cleaner case according to the present invention includes: A reduction chamber is formed integrally with the air cleaner case in the clean side, one end of a reduction passage extending from the engine side is connected to a lower part of the reduction chamber, and a communication port communicating with the clean side is provided at an upper part of the reduction chamber. In addition, a gas-liquid separation unit including a bent passage is provided between the connection portion of the reduction passage and the communication port.

[0005]

The blow-by gas collected in the breather chamber of the engine is sucked into the air cleaner case by the negative pressure of the intake air, so that it enters the lower part of the reduction chamber through the reduction passage and passes through the bent passage of the gas-liquid separation section. The gaseous component containing oil enters the clean side through the communication port and is supplied to the vaporizer, while the liquid component such as water flows down the bent passage and enters the reduction passage. Is returned to the breather chamber on the engine side.

For this reason, the conventional drain piping is not required, and the piping structure is correspondingly simplified. In addition, since the reduction chamber is formed in the clean side integrally with the air cleaner case, the reduction chamber can be easily formed and can be directly communicated into the clean side without the need for a guide tube. Therefore, the structure of the entire reduction device can be simplified, and the number of parts can be reduced, so that the cost can be reduced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention applied to a motorcycle will be described with reference to the drawings. Figure 1 shows the automatic 2
FIG. 2 is an enlarged view showing a side surface of a main part around the engine, FIG. 3 is a side view showing an air cleaner case part further enlarged, and FIG. FIG. 5 is a side view of the case body showing the inside with the lid removed, and FIG. 6 is a partially enlarged view showing a part of the reduction chamber in a cutaway manner.

First, the overall structure of the motorcycle will be outlined. As shown in FIG. 1, this motorcycle is configured as an American type and has a front wheel 1 and a rear wheel 2 forming a long wheelbase, a front fork 3 having a large caster angle, a drop handle 4, a teardrop type fuel tank 5, and It has a characteristic structure such as a tandem seat 6 having a relatively low mounting position and a backrest 7 provided at a rear portion thereof.

The engine 8 disposed between the front and rear wheels is, for example, a small air-cooled engine of about 100 cc. The air is exhausted through an exhaust pipe 11 and a muffler 12 extending rearward from an exhaust port.

The carburetor 10 is supplied with fuel from a fuel tank 5 and is supplied with fresh air from a rear air cleaner case 13. The carburetor 10 is disposed in a space between the front side covers 14 provided below the fuel tank 5 as a pair. The air cleaner case 13 is disposed behind the carburetor 10, and the left and right sides are covered by a center side cover 15.

The engine 8 is supported by a front portion of the vehicle body frame which forms a substantially loop shape in a side view (FIG. 1) of the vehicle body frame.
The upper pipe 17 extends rearward from the head pipe 16 along the center of the vehicle body to support the fuel tank 5, and is bent at a substantially central portion of the vehicle body to move downward. It extends and connects to the pivot plate 20.

A rear portion of the body frame extends substantially horizontally rearward from the bent portion of the upper pipe 17 as a pair of left and right sides to support the tandem seat 6, and a lower pipe 1
9 and a side frame 23 extending obliquely upward and rearward on the side of the pivot plate 20 continuously from the rear end and connected to an intermediate portion of the seat rail 22 to form a substantially truss-like shape. An air cleaner case 13 is arranged in the space (2), and this space is further covered with the center side cover 15.

The pivot plate 20 has a rear fork 2
4 is swingably supported at a front end thereof, and a rear wheel 2 is provided at a rear end thereof.
Is supported. Reference numeral 25 in FIG.

Next, the structure around the engine will be described in more detail with reference to FIG. The carburetor 10 is connected to the air cleaner case 13 via the convey 30 and connected to the intake port of the cylinder head 9 via the intake pipe 31. Further, an air vent tube 33 having one end connected to the float chamber 32 of the vaporizer 10 is provided along the con tube 30, and the other end is opened near the air cleaner case 13.

One end of a reduction passage 35 formed of a tube or the like is connected to a breather chamber provided in the crankcase 34 of the engine 8, and the other end extends rearward above the crankcase 34 to extend the air cleaner case 13. Connected to a reduction chamber 36 provided therein.

As shown in FIGS. 3 and 4, the air cleaner case 13 has a case body 40 opened toward the left side of the vehicle body, a cover 41 covering the opening, and a space between the case body 40 and the cover 41. , A clean side 43 inside the case body 40 and a dirty side 4 inside the lid 41 with the filter 42 interposed therebetween.
4 is made.

Further, a part of the clean side 43 includes:
A reduction chamber 36 formed as an integral small chamber by partially projecting the bottom of the case body 40 to the right side of the vehicle body is provided, and an opening 45 thereof is closed by a reduction chamber lid 46,
It is separated from the clean side 43.

A duct 47 is provided on the rear side of the lid 41. One end of the duct 47 opens into the dirty side 44, and the other end extends to the rear of the air cleaner case 13 and opens. For this reason, the outside air sucked into the dirty side 44 from behind the air cleaner case 13 is filtered by the filter 42 and then enters the clean side 43,
It is sent out to the con tube 30 from the front surface of the case body 40.

As shown in FIG. 4, the air vent tube 3
3 is a tube 3 near the case body 40.
0 It is supported by a guide portion 37 integrally formed on the outer peripheral portion. The range from the portion where the guide portion 37 is provided to the open end 49 of the air vent tube 33 is covered by the front end covering portion 48 of the center side cover 15 on the right side of the vehicle body, and its appearance is blocked.

In FIG. 4, reference numeral 38 denotes a tool box formed integrally with the case body 40, and reference numeral 39 denotes a drain pipe communicating with the dirty side 44.

The detailed structure of the reduction chamber 36 will be described with reference to FIGS. The reduction chamber 36 is located in the vicinity of the inlet of the con tube 30 opening to the clean side 43, and a joint 50 provided thereunder is formed integrally with the case main body 40 to protrude therefrom, and communicates with the reduction passage 35 here. .

The upper part of the reduction chamber 36 communicates with the clean side 43 through a communication port 51 formed in the upper part of the lid 46 for the reduction chamber (FIG. 6). The reduction chamber cover 46 is opened and closed by heat caulking at upper and lower fixing portions 52 arranged diagonally.
And is integrally attached.

Between the joint 50 at the lower end and the communication port 51 at the upper end, a bent passage 54 is formed by ribs 53 formed integrally with the inner wall surface of the reduction chamber 36 and alternately projecting in the horizontal direction. The part is a gas-liquid separation part.

Next, the operation of this embodiment will be described. FIG.
As shown in FIGS. 4 and 5, the blow-by gas collected in the breather chamber of the crankcase 34 is sucked by the intake negative pressure applied to the air cleaner case 13 from the carburetor 10 side, and is reduced from the joint portion 50 through the reduction passage 35. While entering the lower part of the chamber 36 and moving upward through a bent passage 54 forming a gas-liquid separation part, gas-liquid separation is performed.

Gas components such as oil enter the clean side 43 through the communication port 50 and are supplied to the vaporizer 10 from the con tube 30 together with the clean air filtered by the filter 42.

On the other hand, the liquid component such as water flows down the bent passage 54 and returns from the joint portion 50 through the reduction passage 35 to the breather chamber of the crankcase 34.
The liquefied oil and water remaining in the inside are recovered into a mixed liquid.

Therefore, since the gas-liquid separated liquid component repeats the reduction process, the efficiency of collecting scattered fuel and the like increases, and the breather chamber in the crankcase 34 can secure a sufficient capacity. There is no problem even if the liquid component is recovered. For this reason, since it is not directly discharged to the outside of the vehicle through the drain pipe as in the related art, an independent drain pipe is not required, and the piping structure is simplified accordingly.

In particular, in a small engine in which the absolute amount of water in the blow-by gas is small, the amount of liquid components such as returned water is small. Therefore, the liquid component is collected in a relatively small breather chamber of the crankcase 34. However, there is no problem at all, and as a result, it is suitable for an engine with low blow-by gas.

Further, the reduction chamber 36 can be easily formed by integrally forming the reduction chamber 36 into the clean side 43 and the air cleaner case 13 and directly opening the communication port 50, and the communication port 50 is provided near the inlet of the con tube 30. With the opening, there is no need to provide a conventional guide tube.
For this reason, the number of parts can be reduced and the structure can be simplified, and the amount of adhesion to the filter 42 can be reduced as much as possible.

In addition, since the reduction chamber 36 can be formed by widening the air cleaner case 13 in the vehicle width direction, even if the space for disposing the vehicle body in the vertical direction with respect to the air cleaner case 13 is large, the reduction chamber 36 can be formed. In addition, each capacity of the clean side 43 can be easily secured as necessary and sufficient.

The present invention is not limited to the above-described embodiment, but can be applied in various ways. For example, it can be applied to internal combustion engines in various vehicles other than motorcycles. In addition, the lid 4 for the reduction chamber
6 is not mounted inside the clean side 43, and the cover 4
6 can be opened to the outside of the case main body 40 and attached outside. Further, the breather chamber of the engine is not limited to the crankcase 34 but can be provided in another appropriate place.

[Brief description of the drawings]

FIG. 1 is a left side view of a motorcycle to which an embodiment is applied.

FIG. 2 is an enlarged view showing a side surface of a main part around the engine.

FIG. 3 is a side view showing the air cleaner case part further enlarged.

FIG. 4 is a cross-sectional view thereof.

FIG. 5 is a side view of the case main body portion showing the inside with the lid removed.

FIG. 6 is a partially enlarged view showing a part of the reduction chamber cut away.

[Explanation of symbols]

10: vaporizer, 13: air cleaner case, 30: con tube, 33: air vent tube, 35: reduction tube, 36: reduction chamber, 40: case body, 41: lid,
42: filter, 43: clean side, 44: dirty side, 46: lid for reduction chamber, 50: joint, 5
1: communication port, 54: curved passage

Claims (1)

[Claims] 1. A blow-by gas reducing apparatus for an internal combustion engine for reducing blow-by gas from an engine to a clean side of an air cleaner case, wherein a reducing chamber is formed integrally with the air cleaner case in the clean side. And one end of a reduction passage extending from the engine side, and a communication port connected to the clean side is provided above the reduction chamber, and a gas-liquid separation formed by a bent passage between the connection portion of the reduction passage and the communication port. A blow-by gas returning device characterized by comprising a part.