JPH0124324Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a breather device for controlling the pressure in the crank chamber through the tappet chamber in a four-stroke engine.

(Prior art) Conventionally, in a 4-cycle engine, a breather device is used to reduce the average pressure in the crankcase in order to prevent oil leakage from the engine and return lubricating oil accumulated in the circulation passage into the crankcase. The pressure is controlled to negative.

FIG. 1 shows a schematic side view of a conventional vertical shaft type four-stroke engine. In this figure, 1 is a crankcase, 2 is a cylinder, 3 is a crankshaft, 4 is a piston, 5 is a crankcase cover, and 6 is an oil pan.

As shown in FIG. 2, a tappet chamber 7 is formed on the side of the cylinder 2. Tappet chamber 7 is the first
It also serves as an oil/gas separation chamber 8, and is provided with a first ventilation hole 10 and a first oil return hole 11 between it and the crank chamber 9.
A side opening of the first oil/gas separation chamber 8 is closed by a housing 13 that forms a second oil/gas separation chamber 12 . The first oil/gas separation chamber 8 and the second oil/gas separation chamber 1
A second oil hole 15, which is opened and closed by a check valve 14, and a second oil return hole 16 located below the second oil hole 15 are provided between the two. Further, the second oil/gas separation chamber 12 is provided with a third vent hole 17 connected to an air cleaner (not shown).

In the above configuration, when the piston 4 is operated toward the lower dead center (rightward in FIG. 1), the air pressure in the crank chamber 9 increases, causing the check valve 1
4 is opened, and the first oil/gas separation chamber 8 and the second oil/gas separation chamber 1 are opened.
The two spaces communicate. That is, the air in the crank chamber 9 flows from the first vent hole 10 to the first oil/gas separation chamber 8 and passes through the second vent hole 15 to the second oil/gas separation chamber 12.
run away to Furthermore, when the piston 4 moves toward the top dead center, the air pressure in the crank chamber 9 decreases,
When the check valve 14 is closed, outside air is drawn into the crank chamber 9 only through the second oil return hole 16, which has a small cross-sectional area, along with the oil separated in the second oil/gas separation chamber.

That is, in the above configuration, by discharging air from the crank chamber 9 and suppressing the inflow of outside air into the crank chamber 9, the average pressure in the crank chamber 9 is maintained at a negative pressure while the engine is operating.

Furthermore, as described above, when air is discharged from the crank chamber 9, the air contains
This includes particles of lubricating oil 18 stored therein. The oil particles in the air are the first
By sequentially changing the flow direction while flowing to the oil-gas separation chamber 8, the second oil-gas separation chamber 12, and the third ventilation hole 17, the first oil-gas separation chamber 8 and the second oil-gas separation chamber 1 are
2 and returns to the crank chamber 9 through each oil return hole 11, 16. At this time, the oil particles that escaped from the second oil/gas separation chamber 12 to the third oil hole 17 are incinerated by the engine through an intake passage (not shown).

By the way, as shown in FIG. 2, the first oil/gas separation chamber 8
Since the tappet shaft hole 19 is provided in the wall surface of the housing, splashing and infiltration of oil from the crank chamber 9 to the first oil/gas separation chamber 8 is unavoidable. The oil that has entered is stirred by a valve spring (not shown) and scattered. However, in the configuration in which the second oil/air separation chamber 12 is arranged side by side with the first oil/air separation chamber 8, the oil in the first oil/air separation chamber 8 is constantly opened and closed, especially when the engine is tilted. The second oil/gas separation chamber 1 is
2, and the amount of oil flowing into the engine from the intake passage (not shown) increases dramatically. In this case, the engine generates white smoke that causes air pollution, and oil consumption increases.
Frequent controlled replenishment will be required.

In addition, since the oil separated from oil and gas by the second oil and gas separation chamber 12 returns to the crank chamber 9 via the first oil and gas separation chamber 8, a valve spring (not shown) in the second oil and gas separation chamber 8 is used. There is a risk that the oil will scatter again due to the operation of step 1), which will prevent the oil from returning. Therefore, as expected, oil consumption increases and white smoke is generated.

Furthermore, when the second oil/air separation chamber 12 is arranged side by side with the first oil/air separation chamber 8 as described above, the second oil/air separation chamber The depth dimension B of 12 cannot be made large. That is, the oil/gas separation volume of the conventional second oil/gas separation chamber 12 is not sufficient, which tends to promote the generation of white smoke and increase in oil consumption.

Further, the housing 13 of the second oil/gas separation chamber 12 is made of sheet metal consisting of two plates 13a and 13b, and has bent portions and caulked portions 20 of both plates 13a and 13b.
It is difficult to obtain the flatness of the connecting portion 21 of a, 13b and the connecting portion 22 with the first oil/gas separation chamber 8,
These connecting portions 21 and 22 cannot be easily sealed, resulting in increased man-hours and reduced productivity.

Furthermore, as this type of breather device, U.S. Patent No.
Examples include those described in the specification of No. 2693789 (particularly FIG. 3).

Further, as shown in FIG. 7, the second oil/gas separation chamber 12 and the crank chamber 9 are communicated with each other by an oil return pipe 43, so that the oil in the second oil/air separation chamber 12 is transferred to the first oil/air separation chamber 9. A breather device has also been proposed that returns the air to the crank chamber 9 without going through the
No. 85314 (application published on June 9, 1982)). According to this prior art, the oil separated from oil and gas by the second oil and gas separation chamber 12 does not pass through the first oil and gas separation chamber 8, so oil return is improved compared to the conventional example shown in FIG. Since the oil return pipe 43 is separately required, the number of parts increases and the oil return pipe 43 needs to be assembled, resulting in a decrease in productivity. Further, since the housing 13 of the second oil/gas separation chamber 12 is formed of two plates 13a and 13b, this also results in an increase in the number of parts and a decrease in productivity.

(Purpose of the invention) This invention was made to solve the above-mentioned disadvantages, and it prevents oil from entering the second oil-gas separation chamber from the first oil-gas separation chamber, and also prevents oil from entering the second oil-gas separation chamber. It is an object of the present invention to provide a breather device for a four-stroke engine that improves oil/gas separation ability, suppresses the generation of white smoke from the engine and the amount of oil consumed, reduces the number of parts and man-hours, and improves manufacturability. purpose.

(Structure of the invention) In order to achieve the above purpose, this invention first consists of the following:
A second oil/gas separation chamber is formed by integrally protruding the crankcase to the outside of the crank chamber and covering it with a cover. Adjacent to each other via an integral wall, the second oil/gas separation chamber is disposed further outward in the axial direction of the crankshaft than the first oil/air separation chamber. Further, a second oil return hole for returning oil from the second oil/gas separation chamber to the crank chamber is formed in a wall integral with the crankcase, so that the second oil/gas separation is performed without passing through the first oil/gas separation chamber. The chamber is connected to the crank chamber.

(Effects of the invention) According to this invention, the second oil/air separation chamber is arranged axially outward of the crankshaft than the first oil/air separation chamber. Generally, there is a wide space in the radial direction, so the volume of the second oil/gas separation chamber can be set large, thereby ensuring sufficient oil/gas separation capacity. Therefore, in addition to reducing the amount of oil consumed in the crank chamber, even if the second oil/air separation chamber is connected to an air cleaner and the oil particles passing through the second oil/air separation chamber are incinerated by the engine, the amount of oil from the engine will be reduced. It is also possible to suppress the generation of white smoke.

Furthermore, the second oil return hole that returns the oil separated in the second oil/gas separation chamber to the crank chamber communicates with the crank chamber without going through the first oil/gas separation chamber.
Oil will not be scattered again in the first oil/gas separation chamber which is the tappet chamber. Therefore, the amount of oil consumed can be reduced and the generation of white smoke can be suppressed.

Further, since the second oil/gas separation chamber is formed by integrally protruding the crankcase, the second oil/gas separation chamber and the crank chamber are communicated with each other by providing a hole in the wall of the crankcase. The second oil return hole can be formed, and since the second oil return hole is formed in the crankcase wall in this way, unlike the prior art described above, an oil return pipe is not required, and the number of parts is reduced. Manufacturability is improved.

Moreover, since the second oil/air separation chamber is formed by integrally protruding the crankcase and covered with a cover, two plates are required to form the second oil/air separation chamber, unlike the above-mentioned prior art. I don't. Therefore, the number of parts is reduced and manufacturability is improved. Further, the opening can be easily sealed without requiring caulking or the like. Therefore, the number of manufacturing steps is reduced and productivity is improved.

(Example) Hereinafter, an example of this invention will be described based on the drawings.

FIG. 3 is a partially cutaway front view of a breather device for a vertical shaft four-stroke engine according to an embodiment of the invention, and FIG. 4 is a sectional view taken along the line -- in FIG. In FIG. 3, the tappet chamber 7 formed on the side of the crank chamber 9 is connected to the first tappet chamber 7 as in the conventional case.
It is also used as the oil/gas separation chamber 8. A first oil return hole 11 to the crank chamber 9 is provided at the bottom of the first oil/gas separation chamber 8.
However, there is a first ventilation hole 1 from the crank chamber 9 in the side wall.
0 is provided for each. First oil/gas separation chamber 8
A second oil/gas separation chamber 12 integrally formed with the first oil/gas separation chamber 8 and the crank chamber 9 by die-casting is disposed in the upper part of the engine. That is, the second oil/air separation chamber 12 is formed by integrally protruding the crankcase 1 to the outside of the crank chamber 9, and is adjacent to the first oil/air separation chamber 8 via a wall that is integral with the crankcase 1. It is arranged further outward in the axial direction of the crankshaft 3 than the first oil/gas separation chamber 8 .

A check valve 14 is provided between the top surface of the first oil/gas separation chamber 8 and the bottom surface of the second oil/gas separation chamber 12.
A second ventilation hole 15 that opens and closes is provided. A third ventilation hole 17 connected to an intake passage (not shown) is provided at a high position on the side wall of the second oil-gas separation chamber 12.

A second oil return hole 16 having a smaller cross-sectional area than the third ventilation hole 17 is provided at the bottom of the second oil/gas separation chamber 12 . That is, the second oil return hole 16 is formed in the crankcase 1 and is located in the second oil/gas separation chamber 1.
The bottom of the engine 2 communicates with the crank chamber 9 without passing through the first oil/gas separation chamber 8.

The side opening of the first oil/gas separation chamber 8 is covered by a cover 23.
(FIG. 4), and the upper opening of the second oil/gas separation chamber 12 is closed by a cover 24.

The check valve 14 allows only ventilation from the first oil/gas separation chamber 8 to the second oil/gas separation chamber 12, and has a valve seat member 25 press-fitted into the bottom of the second oil/gas separation chamber 12, and a valve seat member 25 in the center. A flexible mushroom-shaped valve body 2 whose lower shaft portion 26a is fitted and locked to the valve seat member 25.
6, and the valve seat member 25 has a second ventilation hole 15.
A plurality of opening/closing holes 15a are provided.

In FIGS. 3 and 4, 27 is an intake valve, 28
is an exhaust valve, 29 and 30 are valve springs, and 31 and 32 are tappets.

The other configurations are the same as those described in FIGS. 1 and 2.

In the above configuration, as in the conventional case, when the air pressure in the crank chamber 9 in FIG.
0 into the first oil/gas separation chamber 8, and the mushroom-shaped valve body 26 of the check valve 14 from the second vent hole 15.
The oil rapidly acts on the oil, pushes up its outer periphery, and escapes into the second oil/gas separation chamber 12. At this time, since the second oil/gas separation chamber 12 is connected to an air cooler (not shown) through the third oil hole 17 having a relatively large diameter, the air in the crank chamber 9 quickly escapes to the air cleaner.

On the other hand, due to the piston movement, the crank chamber 9
When the air pressure inside the check valve 14 decreases, the check valve 14
The valve body 26 immediately elastically returns to the second vent hole 1.
5 is instantly closed, and only from the second oil return hole 16,
Outside air is drawn into the crank chamber 9 together with the oil separated in the second oil/gas separation chamber. Here, since the second oil return hole 16 is smaller than the third ventilation hole 17, the amount of outside air flowing into the crank chamber 9 is small, and therefore,
The negative pressure in the crank chamber 9 is maintained large.

That is, in this embodiment as well, the average pressure in the crank chamber 9 is maintained at a negative pressure while the engine is operating by discharging air from the crank chamber 9 and suppressing the inflow of outside air into the crank chamber 9. Ru.

In addition, oil particles in the air discharged from the crank chamber 9 are transferred from the crank chamber 9 to the first oil/gas separation chamber 8, the second oil/gas separation chamber 12, and the third ventilation hole 1.
During the flow to the first oil-gas separation chamber, the flow direction is sequentially changed, the oil-gas separation chamber is calmed down, and the oil-gas separation chamber comes into contact with obstructions such as the valve springs 29 and 30. 8. The oil remains in the second oil/gas separation chamber 12 and returns to the crank chamber 9 through the respective oil return holes 11 and 16. Further, a small amount of oil particles that escape from the second oil/gas separation chamber 12 to the third vent hole 17 are incinerated by the engine through an air cleaner (not shown).

On the other hand, the second oil and gas separation chamber 12 is the first oil and gas separation chamber 8.
, that is, at a position away from the oil level 18a in the crank chamber 9, so that the oil that has splashed and entered the first oil/air separation chamber 8 from inside the crank chamber 9 during engine operation will further flow into the first oil/air separation chamber 8. Even if the oil is scattered by the valve springs 29 and 30 in the separation chamber 8, or even if the engine is tilted, the oil will not flow through the check valve 1.
4 into the second oil/gas separation chamber 12. Further, since the second oil return hole 16 is located on the upper surface of the crank chamber 9 and is relatively small, the oil in the crank chamber 9 is scattered into the second oil return hole 16 and directly flows into the second oil/air separation chamber 12. It is also almost impossible to penetrate. That is, the amount of oil consumed in the crank chamber 9, which is incinerated by the engine through the air cleaner (not shown) from the second oil/gas separation chamber 12, is small, and therefore, the generation of white smoke from the engine is also reduced.

Moreover, the second oil return hole 16 for returning the oil separated in the second oil/gas separation chamber 12 to the crank chamber 9 communicates with the crank chamber 9 without passing through the first oil/gas separation chamber 8, which is a tappet chamber. ing. Therefore, the oil from the second oil return hole 16 is transferred to the first oil/gas separation chamber 8.
The inner valve springs 29 and 30 prevent it from flying off again. Therefore, the amount of oil consumed can be reduced and the generation of white smoke can be suppressed.

In addition, since the second oil/gas separation chamber 12 is formed by integrally protruding the crankcase 1, by providing a hole in the wall of the crankcase 1, the second oil/gas separation chamber 12 and the crank chamber can be connected to each other. Since the second oil return hole 16 is formed in the wall of the crankcase 1 in this way, the oil return pipe 43 is not required unlike the prior art shown in FIG. Therefore, the number of parts is reduced and manufacturability is improved.

Moreover, since the second oil/gas separation chamber 12 shown in FIG. Two plates are not required to form the . Therefore, the number of parts is reduced and manufacturability is improved.

In addition, in the above configuration, it is noted that in the case of a vertical shaft engine, there is ample space above the first oil/gas separation chamber 8 consisting of the tappet chamber 7, that is, on the side of the relatively wide main bearing. Since the second oil/gas separation chamber 12 is provided in that space, the volume of the second oil/gas separation chamber 12 can be increased to help reduce the white smoke generation and oil consumption. can. Furthermore, the second oil/gas separation chamber 1
2 is integrally formed with the first oil/gas separation chamber 8 and the crank chamber 9 by die casting, and the shapes of the covers 23 and 24 that close the openings of the first oil/gas separation chamber 8 and the second oil/gas separation chamber 12 are simple. The opening can be sealed without caulking or the like, thus reducing the number of manufacturing steps and improving manufacturability.

In addition, in FIG. 3, the first oil return hole 11, the second
The oil return hole 16 is provided parallel to the axis 3a of the crankshaft 3. Both holes 11, 16 like this
Since the axis of the crankcase 1 is along the direction in which the crankcase 1 is molded out as indicated by the arrow A, both the holes 11 and 16 can be easily formed together with the crankcase 1 by die casting.

In the vertical shaft type engine shown in FIG. 3, the first oil return hole 11, the second oil return hole 16
If the engine is set near the corners 33 and 34 at the bottom of each separation chamber, even if the engine is converted to a horizontal shaft type installed by rotating 90 degrees in the direction shown in Fig. 3, the above two oil Return holes 11, 16
Since these will be located near the bottoms of the respective separation chambers 8 and 12, there will be no problem.

As shown in FIG. 5, the check valve 14 may be a reed valve consisting of a valve body 35 made of a metal spring plate and a stopper 36 for regulating the opening angle of the valve body 35.

Figure 6 shows this idea in horizontal shaft type 4.
An example of application to a cycle engine is shown. In the horizontal type shown in this figure, the second oil/gas separation chamber 1
2 are arranged side by side on the side of the first oil/gas separation chamber 8, but since the oil level 18a in the crank chamber 9 is located considerably below, the oil 18 in the crank chamber 9
is difficult to enter the first oil/gas separation chamber 8, that is, the second oil/gas separation chamber 12, and therefore, the second oil/gas separation chamber 1
2 need not be placed above the first oil/gas separation chamber 8. Furthermore, since the first ventilation hole 10 is located at the bottom of the first oil/gas separation chamber 8, it can also be used as the first oil return hole 11. In this case, there is no need to separately provide the first oil return hole 11.

In the configuration shown in FIG. 6, the second oil return hole 16 is
The oil is led from the bottom of the oil/gas separation chamber 12 to the crank chamber 9 through one bearing surface 37 of the crankshaft 3. That is, the oil that accumulates in the second oil/air separation chamber 12 is moved to the bearing surface 37 due to the negative pressure in the crank chamber 9.
After passing through and lubricating this bearing surface 37, it returns to the crank chamber 9. In FIG. 6, 38 is an oil seal.

The second oil return hole 16 of the vertical shaft engine shown in FIG. 3 can also be applied to a bearing surface lubrication device as shown in FIG. 6. In the configuration shown in FIG. 3, the second oil return hole 16 is located in the upper part of the crank chamber 9, so when this second oil return hole 16 is used for lubrication of the crankshaft bearing, it is difficult to lubricate the crankshaft bearing, which has tended to be complicated in the past. Lubricate the upper bearing with a simple configuration.
It can be done easily. Such a lubrication structure can also be applied to a bearing surface of a camshaft (not shown).

[Brief explanation of the drawing]

Figure 1 is a schematic side view of a conventional four-stroke engine, Figure 2 is an enlarged sectional view taken along the line - - in Figure 1, and Figure 3 is a schematic side view of a conventional four-stroke engine.
The figure is a longitudinal sectional front view of a breather device for a four-stroke engine according to an embodiment of this invention, and FIG.
Fig. 5 is a sectional view showing another embodiment of the check valve according to this invention;
The figure is a cross-sectional view showing a modified example of the oil return hole according to this invention, and FIG. 7 is a cross-sectional view showing the main part of the prior art. 1... Crank case, 3... Crankshaft, 7... Tappet chamber, 8... First oil/gas separation chamber,
9... Crank chamber, 10... First ventilation hole, 11...
...First oil return hole, 12...Second oil/gas separation chamber, 14...
...Check valve, 15...Second ventilation hole, 16...
...Second oil return hole, 17...Third ventilation hole, 24...Cover, 37...Bearing surface.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. A first oil/gas separation chamber consisting of a tappet chamber, a crankcase integrally protruding outside the crank chamber, and covered with a cover.
a second oil and gas separation chamber that is adjacent to the oil and gas separation chamber via a wall integral with the crankcase and located further outward in the axial direction of the crankshaft than the first oil and gas separation chamber; and a first oil and gas separation chamber. A first oil return hole from the bottom of the chamber to the crank chamber, and a first oil return hole from the bottom of the second oil/gas separation chamber formed in a wall integral with the crankcase.
A second oil return hole that communicates with the crank chamber without going through the oil/air separation chamber, a first ventilation hole that communicates between the crank chamber and the first oil/air separation chamber, and a first oil/air separation chamber and the second oil/air separation chamber. A second ventilation hole that communicates with the separation chamber;
A breather device for a four-cycle engine, comprising a check valve that allows ventilation only to an oil/gas separation chamber, and a third ventilation hole located above a second oil return hole and provided in the second oil/gas separation chamber. 2. A breather device for a four-cycle engine according to claim 1, wherein the second oil return hole is led from the second oil/gas separation chamber to the crank chamber through the bearing surface of the camshaft or crankshaft.