JPS606576Y2 - Oil blow prevention device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an oil blowout prevention device for preventing valve train lubricating oil from blowing up in an internal combustion engine.

In an internal combustion engine, the inside of the rocker cover that houses the valve mechanism at the top of the crankcase communicates with the crank chamber through an oil return passage on the side of the cylinder, and after lubricating the valve system, the lubricating oil naturally flows down and returns to the crank chamber as appropriate. Conventionally, the outlet of this oil return passage opens straight into the crank chamber in a normally open state (Utility Model No. 48-7992).
7 and Utility Model Application Publication No. 54-48233) Therefore, especially when the oil level in the crank chamber is high due to oil overfilling, oil dilution, etc., a large amount of oil is scraped up by the crank web. , and some of this oil sprays onto the outlet of the oil return passage and blocks it.

In addition, blow-by gas pressure and dynamic pressure when the piston descends are added to the crank chamber, and some of these are blown into the oil return passage.

Particularly during high-speed, high-load operation, the amount of return oil increases and the oil flows down the oil return passage with almost no gaps.
In addition, the blow-by gas pressure and the dynamic pressure when the piston is lowered also increase, so the oil in the oil return passage is pushed up toward the rocker cover.

In this way, the return of oil through the oil return passage becomes extremely poor, resulting in a problem that a large amount of oil remains in the rocker cover, resulting in oil blowing.

The present invention was developed to solve these problems. It prevents the oil scraped up by the crank web from spraying at the outlet of the oil return passage, and also blocks the oil return passage when the piston descends, thereby preventing blow-by. To provide an oil blowout prevention device that improves oil return by eliminating the effects of gas pressure and piston dynamic pressure, and thus prevents oil blowing.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, reference numeral 1 is a crankcase;
An oil pan 2 is attached to the lower part of the crankcase 1 to form a crank chamber 3. A crankshaft 4 is rotatably provided within the crank chamber 3, and lubricating oil is stored at the bottom. There is.

A cylinder 5 is formed in the upper part of the crankcase 1.
A piston 6 inserted into this interior is connected to the crankshaft 4 via a connecting rod 7, and a cylinder head 9 is provided above the cylinder 5, and a rocker cover 10 with a valve mechanism is provided above the cylinder head 9. , so as to run the engine.

Further, the crank chamber 3 is connected to an oil separator 12 provided at the top of the rocker cover 10 through a blow-by gas passage 11 on the side of the cylinder, etc., where the oil is separated and only the blow-by gas is sent to the air cleaner via the pipe 8. Inhaled to the side.

The oil separated by the oil separator 12 becomes together with the oil that has lubricated the valve train in the rocker cover 10, and returns to the crank chamber 3 by flowing down the oil return passage 13 formed on the side of the cylinder 5 etc. It is configured as follows.

Therefore, according to the present invention, the outlet 13 of the oil return passage 13
' is formed obliquely so as to open toward the bottom of the cylinder 5, and its outlet 13' is located at the bottom dead center of the piston 6.
The skirt portion 6' is completely closed.

Since the present invention is constructed in this way, the outlet 13' of the oil return passage 13 is connected to the crankcase 1 forming it.
The oil scraped up by the crank web 14 will no longer be blown into the outlet 13'.

Furthermore, when the piston 6 reaches the bottom dead center and the blow-by gas pressure in the crank chamber 3 and the dynamic pressure when the piston descends reach a peak, the oil return passage outlet 13' is blocked by the piston skirt portion 6'. , the pressure no longer acts on the oil return passage 13.

Therefore, the return oil in the oil return passage 13 is not pushed up toward the rocker cover, but stays there temporarily, and then when the piston rises, the pressure in the crank chamber 3 decreases and the outlet 13' opens, causing the crank Return to room 3 quickly.

As described above, according to the present invention, the oil scraped up by the crank web 14, blow-by gas pressure, dynamic pressure when the piston descends, etc. no longer affect the oil return passage 13, and the oil returns smoothly. Oil blowing caused by a large amount of oil remaining in the tank is reliably prevented.

This reduces oil consumption, prevents oil deterioration, and also prevents troubles such as contamination of the air cleaner, oil accumulation in the oil cleaner, oil dripping outside the air cleaner, and oil contamination in the carburetor.

[Brief explanation of the drawing]

The drawing is a sectional view showing an embodiment of the device according to the present invention. 3... Crank chamber, 6... Piston,
6'...Skirt part, 13...Oil return passage, 13'...Exit.

Claims (1)

[Scope of utility model registration request] The outlet of the oil return passage, which allows the oil that lubricates the valve train etc. to naturally flow down and returns to the crank chamber, is opened toward the cylinder side, and the piston skirt closes the outlet of the oil return passage at approximately the bottom dead center when the cylinder is lowered. An oil blow prevention device characterized by being provided so as to be occluded.