JPS6135716Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a piston for a reciprocating internal combustion engine.

Generally, in an internal combustion engine, lubricating oil is supplied to the sliding surfaces between the cylinder wall and the piston in order to prevent the sliding surfaces from being worn out or burned.

In addition, a plurality of piston rings are fitted to the head of the piston in order to prevent changes in the distance between the pistons due to the operating temperature of the engine and to prevent gas leakage and an increase in lubricating oil consumption due to the above-mentioned lubricating oil rising. A plurality of pressure rings mainly for preventing the gas leak and one oil ring mainly for scraping off lubricating oil are arranged from the head surface toward the piston skirt.

By the way, in conventional pistons, a large amount of lubricating oil adheres to the cylinder wall surface facing the pin hole of the piston pin, and the most lubricating oil is scraped off by the oil ring in this area. Since an oil relief hole is provided in the thin wall part of the oil ring groove forming part other than the piston pin boss part so that the oil ring groove and the hollow part inside the piston communicate with each other, the lubricating oil scraped off near the pin hole is removed. After flowing along the oil ring groove, the oil is returned to the crankcase through the oil relief hole, and a large amount of lubricating oil accumulates in the oil ring groove of the piston pin boss, increasing the pressure and causing the amount of scraping at the piston pin boss. The disadvantage was that there were a lot of In addition, some conventional pistons have a lubricating oil hole below the boss of the piston pin that communicates the hollow part inside the piston with the pin hole, but the oil supplied from this oil hole alone is insufficient for lubrication. It has not yet been possible to completely eliminate the drawbacks such as poor performance and seizure.

This invention was devised with the aim of solving the above-mentioned drawbacks of the conventional structure.The lubricating oil accumulated in the oil ring groove of the piston pin boss is quickly returned to the inside of the crankcase, reducing lubricating oil consumption. Another object of the present invention is to provide a piston for an internal combustion engine that has improved lubricity on the sliding surface of the piston pin.

The structure of the present invention includes a first oil relief hole provided in a thin wall portion other than the piston pin boss portion and communicating between the oil ring groove and the hollow portion inside the piston, and a first oil relief hole provided in the piston pin boss portion and having one end communicating with the oil ring groove. and a second oil relief hole whose other end opens at the fitting part of the piston pin hole with the piston pin, and one end which opens into the fitting part and the other end which opens into a hollow part located at the lower part of the piston pin boss part. The piston for an internal combustion engine is characterized by having a third oil relief hole.

According to the configuration of the present invention, the lubricating oil scraped off by the oil ring on the wall surface other than the cylinder wall surface facing the piston pin hole and accumulated in the oil groove is discharged into the crankcase through the first oil relief hole. Furthermore, the lubricating oil that has been scraped off by the oil ring on the cylinder wall surface facing the piston pin hole and accumulated in the oil groove is discharged into the crankcase through the second oil relief hole, so that the lubricating oil can be removed from the oil groove very quickly. The lubricating oil accumulated in the crankcase can be returned to the crankcase, reducing lubricating oil consumption.

Furthermore, since lubricating oil is supplied to the fitting portion between the piston pin and the pin hole through the second oil relief hole, the lubricity between the piston pin and the pin boss portion can be improved.

Next, the present invention will be explained in detail with reference to embodiments shown in FIGS. 1 to 4, with the same or equivalent parts being denoted by the same reference numerals.

In the first embodiment of the present invention shown in FIGS. 1 to 3, on the outer circumferential surface of the head of the piston 2 reciprocating within the cylinder 1, three
Main ring grooves 3, 4, 5 are provided, and a pressure ring 6 is fitted into each of the upper ring grooves 3, 4,
An oil ring 7 is placed in the ring groove 5 located at the bottom.
are fitted.

The oil ring 7 has a cross-sectional shape V on its outer peripheral surface.
A mold annular groove 8 is provided, and the same annular groove 8
A large number of holes 9 penetrating the inner circumferential surface from the bottom are provided at intervals in the circumferential direction.

Piston pin boss portion 12 at the bottom of the ring groove 5
A slit 11 that communicates with the hollow section 10 in the piston 1 and forms a first oil escape hole is bored in a thin section other than the section C shown by an arrow in FIG.

The piston pin boss portion 12 also has a second oil relief hole 1 which communicates with the bottom of the oil ring groove 5 and the hollow portion 10 from the lower part of the piston pin boss portion 12 through a pin hole 13.
4'', a third oil relief hole 14, and a fourth oil relief hole 14' are bored.

The openings of the second oil drain hole 14 ″ and the third oil drain hole 14 in the pin hole 13 are closed by the sliding surface of the piston pin 15 which faces the fitting portion 13 a of the pin hole 13 with the piston pin 15 .

By the way, the small end of the connecting rod 16 shown by the two-dot chain line is press-fitted and fixed to the piston pin 15.
The large end of connecting rod 16 (not shown) is connected to the crankshaft.

According to the above configuration, when the piston 2 descends during the suction and combustion strokes, the oil ring 7 scrapes off the lubricating oil supplied to the sliding surface of the cylinder 1,
The scraped lubricating oil is then passed through the slit 11 between the oil ring 7 and the wall surface of the ring groove 5 or from the annular groove 8 and hole 9 provided in the oil ring 7.
is guided into the hollow part 10 through the duct, and then returned into the crankcase.

Further, a part of the scraped off lubricating oil is transferred to the piston pin 15 through the second oil relief hole 14''.
The oil is supplied to the hollow portion 10 through the second oil relief hole 14'' and the fourth oil relief hole 14', respectively.

Note that even if the amount of lubricating oil that has flowed into the second oil relief hole 14'' is large, the fourth oil relief hole 1
4', lubricating oil accumulates in the second oil relief hole 14'', the oil pressure in the second oil relief hole 14'' increases, and problems such as lubricating oil flowing back to the cylinder wall surface occur. can be resolved.

By the way, the third oil relief hole 14, which opens into the pin hole 13 from the lower part of the piston pin boss portion 12, serves as a lubricating oil supply hole to the sliding surface of the piston pin 15, which has been commonly used in the past.

In the first embodiment, the fourth oil relief hole 14' opened in the hollow portion 10 is a vertical hole drilled at the same time as the third oil relief hole 14; may be a horizontal hole bored as an extension of the second oil relief hole 14'' as shown in FIG.

As is clear from the above, in each of the above embodiments, the oil ring groove 5 of the piston pin boss portion 12
The lubricating oil that has accumulated in the 2nd oil relief hole 1
4'', pin hole 13 through the fourth oil relief hole 14'
Alternatively, the amount of lubricant remaining on the piston pin boss portion 12 where a large amount of lubricant tends to be scraped off is reduced, reducing lubricant consumption and improving oil lubrication of the piston pin 15. This will eliminate problems such as burn-in.

[Brief explanation of the drawing]

FIG. 1 is a bottom view showing the first embodiment of the present invention, FIG. 2 is a sectional view taken along the line A-A in FIG.
FIG. 4 is a sectional view taken along line B--B in the figure, and FIG. 4 is a sectional view of main parts showing a second embodiment of the present invention. 1...Cylinder, 2...Piston, 3, 4, 5
... Ring groove, 6 ... Pressure ring, 7 ... Oil ring, 8 ... Annular groove, 9 ... Hole, 10 ... Hollow part, 11 ... First oil relief hole (slit), 1
2... Piston pin boss part, 13... Pin hole, 1
3a...Mating part, 14''...Second oil relief hole,
14...Third oil relief hole, 14'...Fourth oil relief hole, 15...Piston pin.

Claims (1)

[Scope of utility model registration request] A first oil relief hole is provided in a thin part other than the piston pin boss part and communicates the oil ring groove with the hollow part in the piston; a second oil relief hole that opens at the fitting portion of the hole with the piston pin; and a third oil relief hole that has one end opening at the fitting portion and the other end opening at a hollow portion located below the piston pin boss portion. A piston for an internal combustion engine, characterized by comprising: