JPS623292B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a breather device for a crank chamber in a four-stroke internal combustion engine, and particularly to a breather device for a four-stroke internal combustion engine, in which a balancer shaft equipped with a balance weight is mounted parallel to the crankshaft in the crank chamber. The present invention relates to a breather device for a crank chamber in a four-stroke internal combustion engine in which a balancer shaft is rotated in conjunction with a crankshaft.

[Prior art]

Conventionally, as a breather device for the crank chamber in a four-stroke internal combustion engine, there is a device in which a communication hole is provided in the crankshaft and the communication hole communicates between the crank chamber and the outside.
As shown in Japanese Patent No. 53-14845, a camshaft has been proposed in which a communication hole is provided in a camshaft mounted parallel to the crankshaft in the crank chamber to communicate the inside of the crank chamber with the outside.

[Problem that the invention seeks to solve]

However, in a crankshaft with a communication hole, the crankshaft is longer in the axial direction due to the necessity of installing a generator, gears, etc. at the end of the crankshaft, and if a breather device is further installed on the crankshaft, the internal combustion There is a problem in that the engine inevitably becomes larger in the direction of the crankshaft. Jitsugyo 53
- The above problem can be solved by providing a communication hole in the camshaft as shown in Publication No. 14845, but
This communication hole is provided concentrically with the camshaft, and since the rotational speed of the camshaft is half that of the crankshaft, oil droplets floating in the crank chamber can easily enter the communication hole together with the breather gas, and the oil droplets that have entered can easily enter the communication hole. There is a problem in that the oil film formed adhering to the inner surface of the hole does not return to the crank chamber again, but is swept away by the flow of breather gas from within the crank chamber and is discharged to the outside. The present invention solves each of the above-mentioned problems.

[Means for solving problems]

For this purpose, the breather device for a four-stroke internal combustion engine according to the present invention, as illustrated in the accompanying drawing, has a balancer shaft provided with a balance weight mounted in parallel with the crankshaft in the crank chamber, so that the balancer shaft is In a four-stroke internal combustion engine that rotates in conjunction with a crankshaft at the same rotation speed or an integral multiple thereof, the balancer shaft is provided with an axial communication hole, and one end of the communication hole is inserted into the crank chamber. and the other end of the communication hole communicates with the outside of the crank chamber via a communication chamber provided on the side of the balancer shaft, and the communication hole is connected to the one end side and the axis of the balancer shaft. The balancer shaft is formed to be inclined so that the distance between the balancer shaft and the shaft center is greater than the distance between the other end and the shaft center.

[Effect]

The balancer shaft rotates at the same rotational speed as the crankshaft or an integral multiple thereof, and the communication hole provided in the balancer shaft is inclined so that one end communicating with the crank chamber is away from the axis of the balancer shaft. Therefore, oil droplets floating in the crank chamber are difficult to enter the communication hole due to centrifugal force, and some oil droplets that have entered the communication hole adhere to the communication hole and form an oil film, which causes the centrifugal force to prevent the crankshaft from entering the communication hole. He is taken back into the room. Furthermore, even if the four-stroke internal combustion engine falls over, the lubricating oil that has entered the communication hole is temporarily stored in the communication chamber, and when the internal combustion engine is started, the lubricating oil in the communication chamber is returned to the crank chamber.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a four-stroke internal combustion engine 10 in which the present invention is implemented.
In the crank chamber 11 of No. 0, a crankshaft 12 and a balancer shaft 13 are mounted parallel to each other. As shown in FIG. 2, the crankshaft 12 is rotatably supported by an inner wall 14a of a crankcase 14 forming the crank chamber 11 via bearings 12a, 12a, and a gear 12b is provided on the right side in the figure.
are fixedly fixed thereto, and crank arms 12c, 12c are integrally formed in the center thereof. A crank pin 12d is inserted through the upper part of each crank arm 12c as shown in the figure.
is connected to cylinder 1 via connecting rod 15.
It is connected to a piston 16 that reciprocates within 6a. The balancer shaft 13 has bearings 13a, 13
It is rotatably supported on the inner wall 14a of the crankcase 14 via the balancer shaft 14, and a fan-shaped balance weight 17 that bulges out in the radial direction of the balancer shaft 13 is integrally provided in the center of the balancer shaft 13. A gear 13b is fixed to the right end in the figure. This gear 13b meshes with the gear 12b of the crankshaft 12, which has the same number of teeth. As a result, the balancer shaft 13 rotates at the same rotational speed as the crankshaft 12 and in the opposite direction, and the inertia of the balance weight 17 serves to alleviate vibrations generated in the internal combustion engine 10 due to the reciprocating movement of the piston 16. . Note that lubricating oil is supplied to the large end sliding contact surfaces of the crank pin 12d and the connecting rod 15 from an oil supply device (not shown) through an oil supply path 12e. The oil level of this lubricating oil is indicated by a dashed line O in FIG.

Next, the breather device 20, which is the main part of the present invention, will be explained.
It is equipped with The communication hole 21 has a small diameter portion 21a that communicates with a radial hole 22 provided in the balance weight 17 at its right end in the drawing, and a large diameter portion 21a that communicates with a communication chamber 23 formed on the left side of the balancer shaft 13 at its left end. It is constituted by a diameter portion 21b. As shown in FIGS. 2 and 3, the small diameter portion 21a is provided eccentrically with respect to the axis of the balancer shaft 13, and the distance from the right end axis is greater than the distance from the left end axis. It is formed slanted like this. The hole 22 is open on the outer peripheral surface of the balance weight 17 and allows the communication hole 21 and the crank chamber 11 to communicate with each other. Further, as shown in FIG. 3, the communication chamber 23 is formed by expanding a part of the crankcase 14, and a connecting pipe 24 is opened inside the communication chamber 23. The breather device 20 is configured as described above. The lower end of a hose 25 is connected to the outer end of the connecting pipe 24, and the upper end of the hose 25 is connected to an air cleaner 18 attached to the internal combustion engine 10, as shown in FIG. Thereby, the crank chamber 11 communicates with the communication chamber 23 through the hole 22 of the balance weight 17, through the communication hole 21 of the balancer shaft 13, and further into the air cleaner 18 through the hose 25. Note that the air cleaner 18 is attached to a carburetor 19 connected to the intake pipe 10a of the internal combustion engine 10.

In the internal combustion engine 10 equipped with the breather device 20 configured as described above, when the internal combustion engine 10 is started, the crank chamber 11 is filled with blow-by gas leaking from between the piston 16 and the cylinder 16a, and the crank chamber The lubricating oil that is scraped up from the bottom of the rotor 11 and lubricates each rotating part becomes minute oil droplets and floats in the blow-by gas. The internal pressure inside the crank chamber 11 increases each time the piston 16 descends, and therefore the blow-by gas inside the crank chamber 11 is transferred to the hole 22 of the breather device 20 and the communication hole 2.
1. It is pushed out into the air cleaner 18 through the communication chamber 23 and the hose 25, and further flows into the intake pipe 10a through the carburetor 19. By the way, since the balancer shaft 13 provided with the balance weight 17 is rotating at the same high speed as the crankshaft 12, blow-by gas in the vicinity becomes a rotating flow, and large oil droplets in this rotating flow are The centrifuged gas hardly flows into the hole 22 of the balance weight 17, and mainly only light blow-by gas flows into the hole 22 of the balance weight 17. Further, some oil droplets that have entered the holes 22 of the balance weight 17 are subjected to centrifugal force within the holes 22 and are discharged to the outside of the balance weight 17. Furthermore, some of the oil droplets that have entered the communication hole 21 adhere to the inner surface of the small diameter portion 21a and form an oil film, and since this small diameter portion 21a is inclined as described above, the oil film adhering to the inner surface is caused by centrifugal force to cause the right end It is returned to the side and returned into the crank chamber 11 through the hole 22. Therefore,
According to this breather device 20, the crank chamber 11
The blow-by gas inside the air cleaner 18 completely separates the lubricating oil droplets floating therein.
It is smoothly discharged inside. Note that the centrifugal force that is effective in separating oil droplets conversely directs blow-by gas through the communication hole 2.
However, in this embodiment, the crank chamber 11 is connected to the air cleaner 18 with a large negative pressure.
This problem is solved by connecting the filter to the downstream side of the filter and forcibly drawing the blow-by gas.

Furthermore, if, for example, a motorcycle to which the internal combustion engine 10 is installed falls, a portion of the lubricating oil at the bottom of the crank chamber 11 will pass through the hole 22 of the balance weight 17 and enter the communication hole 21 of the balancer shaft 13. There may be slight intrusion. However, since this lubricating oil is temporarily stored in the communication chamber 23, when the two-wheeled motor vehicle is raised, the lubricating oil in the communication chamber 23 does not remain there, and the communication hole 21, the hole 22
It is returned to the crank chamber 11 through the hose 25, and does not enter the hose 25.

In the above embodiment, an example was explained in which the upper end of the hose 25 connected to the communication chamber 23 was connected to the air cleaner 18 as a means for communicating the other end of the communication hole 21 with the outside of the crank chamber 21.
For example, connect the upper end of this hose 25 (or the outer end of the connecting pipe 24 opened into the communication chamber 23) to the vaporizer 1.
9. It may be implemented by connecting to the intake pipe 10a, etc.

Further, in the above embodiment, the balancer shaft 13
An example has been described in which the right end of the communication hole 21 provided at the axis of the balance weight 17 is communicated with the hole 22 of the balance weight 17. You may let them.

Further, in the above embodiment, the balancer shaft 13
The balancer shaft rotates at the same speed as the crankshaft 12 to eliminate primary unbalance of the crankshaft, but the balancer shaft rotates at a rotational speed that is an integral multiple of the crankshaft to eliminate secondary or higher unbalance. But that's fine.

〔Effect of the invention〕

As described in detail above, in the present invention, lubricating oil droplets are suspended in the crank chamber by tilting the communicating hole 21 formed in the balancer shaft 13, which rotates at the same speed as the crankshaft 12 or an integral multiple thereof, as described above. This reduces the amount of lubricant that enters into the communication hole 21 together with the blow-by gas, and also returns some lubricant oil that once entered and adhered to the inner surface of the communication hole 21 into the crank chamber, thereby eliminating the lubricant droplets floating in the crank chamber. The blowby gas can be reliably separated from the blowby gas and only the blowby gas can be smoothly discharged to the outside of the crank chamber, and the leakage of lubricating oil in the event of a fall can be reduced due to the storage function of the communication chamber 23.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway side view of a four-stroke internal combustion engine embodying the present invention, Fig. 2 is a vertical sectional view taken along line - in Fig. 1, and Fig. 3 is a longitudinal sectional view taken along line - in Fig. 2. It is a partially enlarged plan view. Explanation of symbols, 10...4-stroke internal combustion engine, 1
1...Crank chamber, 12...Crankshaft, 13...
...Balancer shaft, 14...Crankcase, 18...
...Air cleaner, 20... Breather device, 21...
...Communication hole, 22...hole, 23...communication room, 24...
...Connection pipe, 25...Hose.

Claims (1)

[Claims] 1. A balancer shaft provided with a balance weight is mounted parallel to the crankshaft in the crank chamber, and the balancer shaft is rotated in conjunction with the crankshaft at the same rotational speed or an integral multiple thereof.4 In the cycle internal combustion engine, the balancer shaft is provided with an axial communication hole, one end of the communication hole communicates with the crank chamber, and the other end of the communication hole is provided on the side of the balancer shaft. communicates with the outside of the crank chamber through the communication hole, and the distance between the one end of the communication hole and the axis of the balancer shaft is greater than the distance between the other end and the axis of the balancer shaft. A breather device for a crank chamber formed at an angle on the balancer shaft.