JP2001271706A - Structure of piston - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure of a divided type piston capable of preventing increase of oil consumption. SOLUTION: A radially inward height of walls 14, 15 of an oil reservoir 13 disposed on an upper end of a skirt portion 10 is larger than an radially outward height thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston structure comprising two members, a crown portion and a skirt portion.

[0002]

2. Description of the Related Art A split type piston in which a crown portion and a skirt portion are formed as separate members in a piston of an internal combustion engine is known (for example, Japanese Patent Application Laid-Open No. 8-338303, Japanese Utility Model Application Laid-Open No. 5-36055). Gazette).

[0003] In any of the above techniques, it is unavoidable that a gap is formed at the joint between the crown and the skirt due to the structure. Then, piston cooling oil and the like supplied to the inside of the piston leak from the gap to the outer periphery.
Therefore, the oil consumption of the engine increases. There is also a problem that the combustion of the engine oil has a bad influence on the environment.

[0004]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above-mentioned problems in the prior art, and has as its object to provide a split piston structure which is simple in structure and does not increase oil consumption. I have.

[0005]

According to the piston structure of the present invention, a groove-shaped oil reservoir is provided at the upper end of the outer periphery of the skirt portion in a piston structure composed of two members, a crown portion and a skirt portion. The height of both side walls of the groove-shaped oil reservoir is configured such that a radially inner wall of the piston is lower than a radially outer wall.

Here, the groove-shaped oil reservoir is divided into a plurality of portions, and one portion between the oil reservoirs is used as an oil inlet and the remaining portion is used as an oil drain. Preferably, it is configured.

[0007] According to the structure of the piston of the present invention having the above-described structure, the oil in the oil reservoir flows inward in the low radial direction of the wall due to the vertical movement of the piston.
Oil does not flow to the outer circumference. Therefore, the oil consumption is suppressed.

Further, if the groove-shaped oil reservoir is divided into a plurality of portions, one portion between the oil reservoirs is used as an oil inlet and the remaining portion is used as an oil dropper, the oil can be removed. Since oil is prevented from overflowing to the outer peripheral side of the piston, oil consumption is reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a split type piston, which is constituted by a conventionally known crown portion 1 and a skirt portion 10 according to the present invention. Here, reference numeral 2 denotes a combustion chamber, 3 denotes a ring groove rear portion, 4 denotes a ring groove, 5 denotes a piston pin hole,
1a indicates a bush.

In the lower part of the crown portion 1, a piston pin hole of the skirt portion 10 (hereinafter, referred to as a "pin hole").
Numeral 11 is combined with the bush 1a of the crown portion 1 so that a piston pin (not shown) penetrates. The piston pin (not shown) is prevented from coming off by a clip (not shown) engaged with the groove 12. An oil reservoir 13 is formed at the upper end of the skirt 10.

FIG. 2 is a plan view of the skirt portion 10, and the oil sump 13 is provided in a plurality of (four in the illustrated example). Oil sump 13 and oil sump 1
3 is designated by the reference numeral 18, and the portion 18 between them is formed as a portion between the widened spaces by the oil sump 23 having a different shape only at one position. The middle part is designated by the reference numeral 19.

At a portion indicated by reference numeral 19, a passage serving as an inlet of oil jetted from an oil jet 30 (indicated by a chain line) provided below the cylinder liner is formed.

FIG. 3 shows a side sectional view of the skirt portion 10,
The upper end of the radially inner wall 15 forming the oil reservoir 13 has a reference sign H as compared with the upper end of the radially outer wall 14.
It is formed so as to be lower by the dimension (for example, 2 mm) indicated by.

The notch 17 provided at the lower end of the skirt portion 10 indicates the escape of the oil jet 30 from a nozzle (not shown).

FIG. 4 is a sectional view taken along line AA of FIG. 3, and FIG.
As shown above, reference numeral 11 indicates a pin hole, 12 indicates a clip groove, and 18 indicates an outer peripheral portion of the skirt portion 10, respectively.

Hereinafter, the operation will be described. The oil jet 30 injected upward from the nozzle provided in each cylinder collides with the top of the ring groove back side 3 of the crown portion 1 and scatters and falls, and the oil pools 13 and 23
Accumulate in Then, when the piston descends, the oil scatters on the back side 3 of the ring groove, cools, and returns to the oil reservoir.

The oil reservoir 13 is in a state where the oil injected from the nozzle is replenished and the oil is always accumulated, but the inner wall 15 in the radial direction is replaced with the outer wall 14 in the radial direction.
Since it is lower (2 mm lower in this embodiment), oil leaks inward in the lower radial direction of the wall when the piston is raised, and prevents oil from overflowing to the outer peripheral side of the piston.

Although the embodiment in which the oil reservoir 13 is divided into four portions has been described above, the number of divisions is not limited to the above, and the oil reservoir 13 may be formed in a ring-shaped groove without being divided. .

[0019]

The present invention is configured as described above, and can provide the following excellent effects. (1) The oil in the oil pool flows inward in the radial direction with a low wall due to the vertical movement of the piston, so that the oil does not flow out to the outer periphery. (2) Therefore, the oil consumption is kept low, and adverse effects on the environment are also prevented. (3) If the groove-shaped oil sump is divided into a plurality of parts, and one part between the oil sump and the oil sump is used as an oil inlet and the remaining part is used as an oil dropout, Oil is prevented from overflowing to the outer peripheral side of the piston, and oil consumption is reduced.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a piston showing one embodiment of the present invention.

FIG. 2 is a plan view of the skirt portion of FIG. 1;

FIG. 3 is a side sectional view of the skirt portion of FIG. 1;

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is a sectional view taken along line BB of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Crown part 2 ... Combustion chamber 4 ... Ring groove 5, 11 ... Piston pin hole 10 ... Skirt part 12 ... Clip groove 13 ... Oil reservoir 14, 15 ... Oil reservoir wall

Claims (2)

[Claims] In a piston structure comprising two members, a crown portion and a skirt portion, a groove-shaped oil reservoir is provided at an upper end of an outer periphery of the skirt portion, and a height of both side walls of the groove-shaped oil reservoir is provided. Is characterized in that a radially inner wall of the piston is lower than a radially outer wall. 2. A structure in which the groove-shaped oil reservoir is divided into a plurality of portions, and one portion between the oil reservoirs is an oil inlet portion and the remaining portion is an oil drop port. 2. The structure of the piston of claim 1, wherein