JPH11182334A - Piston for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piston for internal combustion engine which excels in the lubrication property by utilizing the lubricating oil reaching the hollow inside of a piston pin effectively. SOLUTION: A piston pin hole 10 is formed at a predetermined position of a piston 1, and a hollow and cylindrical piston pin 12 is mounted in this piston pin hole 10. Peripheral grooves 11 are formed at both ends of the piston pin hole 10. Blocking plates 17 which cover a part of an opening part of a hollow hole 15 of the piston pin 12 and form an oil collection part 16 in the hollow hole 15 of the piston pin 12 are provided at both ends of the piston pin 12. Both ends of the piston pin 12 are cut in such a way that a length (L1) in the axial direction of the piston pin 12 in the direction of gravity is longer than a length (L2) in the axial direction in the opposite direction of gravity. A cut fringe 18 of the piston pin 12 is arranged by facing the peripheral grooves 11 formed at both ends of the piston pin hole 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a piston for an internal combustion engine, and more particularly to a piston for an internal combustion engine having good lubrication between a piston pin hole and a piston pin.

[0002]

2. Description of the Related Art As shown in FIG. 6 of Japanese Patent Application Laid-Open No. 7-139629, for example, this type of piston for an internal combustion engine has a piston pin hole formed at a predetermined position of the piston, and a hollow hole is formed in the piston pin hole. A cylindrical piston pin is mounted.

[0003] Lubrication of an internal combustion engine is performed by supplying lubricating oil in an oil pan to various lubricating parts by an oil pump, and is also performed using an oil splash accompanying rotation of a crankshaft. The oil that has been lubricated in each of the lubricating portions is returned to the oil pan along the wall surface of each portion.

When the lubricating oil circulates, a part of the lubricating oil also reaches the hollow inside of the piston pin during operation of the internal combustion engine when the piston pin has a hollow cylindrical shape.

[0005]

However, in the prior art, the lubricating oil that has reached the hollow inside of the piston pin during operation of the internal combustion engine only drops into the oil pan from both open ends of the piston pin. It does not serve as a special lubrication.

The present invention has been devised in view of the above-mentioned conventional circumstances, and provides a piston for an internal combustion engine having excellent lubrication by effectively utilizing the lubricating oil that has reached the hollow interior of the piston pin. Aim.

[0007]

SUMMARY OF THE INVENTION Therefore, the present invention is directed to an internal combustion engine having a piston pin hole formed at a predetermined position of a piston and a hollow cylindrical piston pin mounted in the piston pin hole. In the piston for use, a circumferential groove is formed at both ends of the piston pin hole, and at both ends of the piston pin, a part of the opening of the hollow hole of the piston pin is covered, and an oil reservoir is formed in the hollow hole of the piston pin. While providing a weir plate to form, both ends of the piston pin,
The piston pin is cut so that the axial length of the piston pin in the gravity direction is longer than the axial length in the antigravity direction, and the cut edges at both ends of the piston pin are formed at both ends of the piston pin hole. It is configured to be arranged facing the groove.

Further, the invention according to claim 2 has a structure in which, in the structure of the invention according to claim 1, the dam plate is formed integrally with the piston pin.

According to a third aspect of the present invention, in the configuration of the first aspect, both ends of the piston pin are cut so as to be inclined with respect to the axial direction of the piston pin. is there.

In such a configuration, when the lubricating oil circulates during operation of the internal combustion engine, part of the lubricating oil also reaches the hollow interior of the piston pin.

The lubricating oil that has reached the inside of the hollow of the piston pin is blocked by the blocking plate, and accumulates in the oil sump in the hollow hole by gravity.

Subsequently, the lubricating oil that has reached the hollow interior of the piston pin and has accumulated in the oil sump moves due to the inertia of the lubricating oil during the movement of the piston, and moves into the circumferential grooves formed at both ends of the piston pin hole. Leads to.

That is, when the piston reciprocates in each of the steps of suction, compression, expansion, and exhaust, the lubricating oil in the oil sump transitions from movement in the antigravity direction to movement in the gravity direction (for example, During the transition from the compression stroke to the expansion stroke, or from the exhaust stroke to the suction stroke), it moves in the anti-gravity direction to reach a portion in the circumferential groove located in the anti-gravity direction. That is, since the axial length of the piston pin is long in the gravity direction and short in the anti-gravity direction,
The lubricating oil in the oil reservoir overflows from the cutting edge of the piston pin, which is short in the axial direction, and reaches the portion located in the anti-gravity direction in the circumferential groove.

Further, the lubricating oil in the portion of the circumferential groove located in the anti-gravity direction is subjected to a process in which the piston moves from the movement in the gravity direction to the movement in the anti-gravity direction (for example, from the expansion stroke to the exhaust stroke, or In the process of shifting from the suction stroke to the compression stroke), it moves in the direction of gravity, and reaches a portion in the circumferential groove located in the direction of gravity.

At the same time, in the process of the piston shifting from the movement in the direction of gravity to the movement in the direction of antigravity (eg, the process of shifting from the expansion stroke to the exhaust stroke or from the suction stroke to the compression stroke), Part of the lubricating oil in the portion of the circumferential groove located in the antigravity direction moves into the oil reservoir.

That is, the axial length of the piston pin is
Since it is formed long in the direction of gravity and short in the direction of antigravity, when the lubricating oil of the portion of the circumferential groove located in the direction of antigravity moves in the direction of gravity, it is captured by the cutting edge of the axially long piston pin, The lubricating oil in the hollow hole of the piston pin is blocked by the blocking plate and accumulates in the oil reservoir. The lubricating oil that has moved into the oil reservoir moves again with the subsequent movement of the piston in the direction of gravity.

The lubricating oil that has reached the circumferential groove lubricates between the piston pin hole and the piston pin, and then drops into the oil pan.

Thus, the lubricating oil that has reached the hollow inside of the piston pin during operation of the internal combustion engine is used for lubrication between the piston pin hole and the piston pin.

Therefore, the lubricating oil that has reached the hollow inside of the piston pin is effectively used, and a piston for an internal combustion engine having excellent lubrication can be obtained.

According to the second aspect of the present invention, since the blocking plate is formed integrally with the piston pin, the blocking plate can be easily formed.

According to the third aspect of the present invention, since both ends of the piston pin are cut at an angle with respect to the axial direction of the piston pin, machining of both ends of the piston pin is facilitated. Become.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view of a piston for an internal combustion engine showing an embodiment of the present invention, and FIG. 2 is an enlarged view showing a main part of FIG.

In FIG. 1, reference numeral 1 denotes a piston. The piston 1 has an uppermost crown portion 2 in FIG.
And a skirt portion 4 following the ring land portion 3. The ring land part 3
In this embodiment, three piston ring grooves 5, 6, 7 are formed in this embodiment. Of these piston ring grooves 5, 6, 7, two piston ring grooves Grooves 5 and 6 are compression ring grooves,
The piston ring groove 7 formed adjacent to the skirt portion 4 is an oil ring groove.

Reference numeral 8 denotes an apron portion formed on the skirt portion 4, and 9 denotes a pin boss portion formed so as to protrude from the apron portion 8 toward the inner peripheral side of the skirt portion 4. The apron portion 8 and the pin boss portion Numerals 9 are formed facing both sides of the axis Y of the piston 1 (see FIG. 1).

The pin boss portion 9 is formed with a piston pin hole 10 having both ends opened in the apron portion 8 facing the skirt portion 4. The axis of the piston pin hole 10 is
It is formed so as to be substantially perpendicular to the axis Y of the piston 1.

At both ends of the piston pin hole 10, circumferential grooves 11 having a predetermined width are formed. Although the peripheral groove 11 is formed to have a constant width in this embodiment, the side surface of the peripheral groove 11, particularly the side surface on the axis Y side of the piston 1, is inclined to form the peripheral groove 11 whose inner peripheral side is wide. be able to.

Reference numeral 12 denotes a piston pin. The piston pin 12 is inserted into the piston pin hole 10 and is press-fitted and fixed in a through hole 14 of the connecting rod 13 to be connected to the connecting rod 13. .

The piston pin 12 is formed in a hollow cylindrical shape, and at both ends thereof, a part of the opening of the hollow hole 15 of the piston pin 12 is covered, and an oil reservoir 16 is formed in the hollow hole 15. A dam plate 17 is formed. In this embodiment, the blocking plate 17 is provided with the piston pin 12.
And extends to a substantially central position in the radial direction of the hollow hole 15, and covers substantially a half circumference of the hollow hole 15. That is, since the blocking plate 17 covers a part of the opening of the piston pin 12 on the opening end side, the lubricating oil accumulates in the hollow hole 15 of the piston pin 12 to a height indicated by a two-dot chain line A. As a result, an oil reservoir 16 is formed in the hollow hole 15 of the piston pin 12.

Further, both ends of the piston pin 12 are cut so as to be inclined with respect to the axial direction of the piston pin 12, and the axial length (L1) of the piston pin 12 in the direction of gravity (the lower side in FIG. 1). Is longer than the axial length (L2) in the anti-gravity direction (upper side in FIG. 1).

When the piston pin 12 is inserted into the piston pin hole 10, the cut edges 18 at both ends of the piston pin 12 face the circumferential grooves 11 formed at both ends of the piston pin hole 10. Have been.

In such a configuration, when the lubricating oil circulates during operation of the internal combustion engine, part of the lubricating oil is
2 will also reach the hollow interior.

The lubricating oil that has reached the inside of the hollow of the piston pin 12 is blocked by a blocking plate 17, and the oil reservoir 16 in the hollow hole 15 of the piston pin 12 is caused by gravity.
Accumulate inside.

Subsequently, the lubricating oil that has reached the hollow interior of the piston pin 12 and has accumulated in the oil reservoir 16 moves due to the inertia of the lubricating oil during the movement of the piston 1.
It reaches into a circumferential groove 11 formed at both ends of the piston pin hole 10.

That is, the lubricating oil in the oil reservoir 16 is
The piston 1 moves in the antigravity direction (upward in FIG. 1) in the process of shifting from the movement in the antigravity direction to the movement in the gravity direction (the process of shifting from the compression stroke to the expansion stroke or from the exhaust stroke to the suction stroke). Then, it reaches a portion (upper side in FIG. 1) located in the anti-gravity direction in the circumferential groove 11. That is, the axial length of the piston pin 12 is longer in the direction of gravity (lower side in FIG. 1), and
(Upper side in FIG. 1), the lubricating oil in the oil sump 16 can be removed from the piston pin 1 which is short in the axial direction.
2 and overflows from the cutting edge 18 to reach a portion (upper side in FIG. 1) located in the circumferential groove 11 in the antigravity direction.

The lubricating oil in the portion (upper side in FIG. 1) of the circumferential groove 11 located in the anti-gravity direction is
1 moves from the movement in the gravity direction to the movement in the antigravity direction (for example, from the expansion stroke to the exhaust stroke or from the suction stroke to the compression stroke) in the direction of gravity (FIG. 1).
To the lower side in FIG. 1), and reaches a portion (lower side in FIG. 1) located in the circumferential groove 11 in the direction of gravity.

At the same time, in the process in which the piston moves from the movement in the gravity direction to the movement in the antigravity direction (for example, in the process of moving from the expansion stroke to the exhaust stroke or from the suction stroke to the compression stroke), A part of the lubricating oil in the portion (the upper side in FIG. 1) of the circumferential groove located in the anti-gravity direction moves into the oil reservoir 16.

That is, the axial length of the piston pin 12 is longer in the direction of gravity (lower side in FIG. 1) and shorter in the direction of antigravity (upper side in FIG. 1). When the lubricating oil of the part located in the direction (upper side in FIG. 1) moves in the direction of gravity, it is captured by the cutting edge 18 of the axially long piston pin 12,
The lubricating oil in the hollow hole 15 of the piston pin 12 is blocked by the blocking plate 17 and accumulates in the oil reservoir 16. In addition, the lubricating oil that has moved into the oil reservoir 16 is
Move in the direction of gravity (downward in FIG. 1).

The lubricating oil that has reached the circumferential groove 11 lubricates between the piston pin hole 10 and the piston pin 12.
In this case, when the circumferential groove 11 is formed such that the inner circumferential side is formed wider by inclining the side surface on the axis Y side of the piston 1, the circumferential surface of the circumferential groove 11 and the outer circumferential surface of the piston pin 12 are formed. Since the angle becomes an acute angle, the lubricating oil
And the piston pin 12 can be penetrated by a wedge action, and effective lubrication is achieved.

The piston pin hole 10 and the piston pin 1
The lubricating oil that has lubricated between the pin 2 and the connecting rod 13 travels along these wall surfaces through a gap between the pin boss 9 and the connecting rod 13 and drops into an oil pan (not shown).

Thus, the lubricating oil that has reached the hollow inside of the piston pin 12 during operation of the internal combustion engine is used for lubrication between the piston pin hole 10 and the piston pin 12.

Therefore, the lubricating oil that has reached the hollow interior of the piston pin 12 is effectively used, and a piston for an internal combustion engine with excellent lubrication can be obtained.

Since the blocking plate 17 is formed integrally with the piston pin 12, the blocking plate 17 can be easily formed.

Further, since the both ends of the piston pin 12 are cut so as to be inclined with respect to the axial direction of the piston pin 12, machining of both ends of the piston pin 12 becomes easy.

Although the embodiment has been described with reference to the drawings, the specific configuration is not limited to this embodiment and can be changed without departing from the spirit of the invention.
For example, although the embodiment in which the blocking plate 17 is formed integrally with the piston pin 12 has been described, the blocking plate 17 may be formed separately from the piston pin 12.

Further, the embodiment in which both ends of the piston pin 12 are cut inclining with respect to the axial direction has been described.

[0047]

As described in detail above, according to the present invention, a lubricating oil which has reached the hollow interior of the piston pin can be effectively used to obtain a piston for an internal combustion engine having excellent lubrication.

[Brief description of the drawings]

FIG. 1 is a sectional view of a piston for an internal combustion engine showing an embodiment of the present invention.

FIG. 2 is an enlarged view showing a main part of FIG. 1;

[Explanation of symbols]

 Reference Signs List 1 piston 10 piston pin hole 11 peripheral groove 12 piston pin 15 hollow hole 16 oil reservoir 17 dam plate 18 cutting edge

Claims (3)

[Claims] In a piston for an internal combustion engine having a piston pin hole formed at a predetermined position of a piston and a hollow cylindrical piston pin mounted in the piston pin hole, circumferential grooves are formed at both ends of the piston pin hole. On the other hand, at both ends of the piston pin, a blocking plate which covers a part of the opening of the hollow hole of the piston pin and forms an oil reservoir in the hollow hole of the piston pin is provided, and both ends of the piston pin are provided. Was cut such that the axial length of the piston pin in the gravity direction was longer than the axial length in the antigravity direction, and cut edges at both ends of the piston pin were formed at both ends of the piston pin hole. A piston for an internal combustion engine, which is arranged facing a circumferential groove. 2. The piston for an internal combustion engine according to claim 1, wherein said dam plate is formed integrally with said piston pin. 3. The piston for an internal combustion engine according to claim 1, wherein both ends of said piston pin are cut so as to be inclined with respect to an axial direction of said piston pin.