JP2583015Y2 - Piston for internal combustion engine - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a piston for an internal combustion engine of an automobile or the like.

[0002]

2. Description of the Related Art Conventionally, in this type of piston, a hollow hole is formed in a skirt portion so as to open in the direction of a piston pin hole in order to reduce the weight, and a piston pin boss is formed to maintain the rigidity of the skirt portion. A support rib connected to the inner peripheral surface of the skirt portion is formed on the skirt portion end side of the portion (for example, Japanese Utility Model Application Laid-Open No. 2-204665).
No.).

[0003]

However, in such a conventional piston for an internal combustion engine, when a load due to combustion pressure is applied to the crown surface of the piston in the operating state of the internal combustion engine, the thrust side of the crown portion is displaced. And the anti-thrust side is pressed in the stroke direction of the piston against the piston pin boss portion, whereby the support rib receives rotational moments opposite to each other on the thrust side and the anti-thrust side about the piston pin boss portion, and the piston on the support rib Tensile stress is generated at both the thrust side and the anti-thrust side root of the pin boss.

For this reason, it is conceivable to take measures to increase the wall thickness in order to secure sufficient strength at the root portion against this tensile stress. However, such measures increase the weight of the entire piston. Therefore, it goes against the weight reduction of the piston.

SUMMARY OF THE INVENTION In view of the foregoing, an object of the present invention is to provide a piston for an internal combustion engine in which the strength of the root of the piston pin boss and the supporting rib is sufficiently ensured, and at the same time the problem of weight reduction is solved. And

[0006]

SUMMARY OF THE INVENTION A piston for an internal combustion engine according to the present invention is formed by hollowing a skirt toward a piston pin boss.
A hole is formed and the piston pin boss and the scar
A support rib that is continuous with the inner peripheral surface of the
When you separate the holding ribs and bring the separated surfaces into contact with each other
In particular, when an axial load due to combustion pressure is applied,
Is formed so as to be relatively slidable .

[0007]

In this configuration, when a force due to the combustion pressure acts on the support ribs, slipping occurs on the separation surface from the piston pin boss, and no tensile stress is generated at the base of the piston pin boss. In addition, the outgoing movement of the piston in the cylinder
When a lateral force (thrust force) is applied to the piston from the inner wall of the cylinder bore by the return movement, the support rib is pressed against the piston pin boss to support the skirt.

[0008]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a front view of a piston for an internal combustion engine employing an embodiment of the present invention, as viewed from the direction of a piston pin hole.

A denotes a piston main body, which is manufactured using a lightweight alloy such as an aluminum alloy as a base material, and includes a crown portion 1 and a skirt portion 2 including a thrust side 2a and a non-thrust side 2b.

A pin boss 4 having a piston pin hole 3 offset to the thrust side of the skirt 2 with respect to the center of the piston body A (center of the cylinder) is connected to the crown 1.

The skirt portion 2 is formed with a hollow 5 which opens in the direction of the piston pin hole 3. Support ribs 6 are formed on the inner peripheral surface sides of the skirt portion 2 on the thrust side 2 a and the anti-thrust side 2 b. , 7 are connected. The support ribs 6 and 7 are supported by the support ribs 6 and 7 of the piston pin boss 4.
Extend to the side of the roots 4a, 4b,
4b, the base 4 of the piston pin boss 4
a, 4b and separating surfaces 9, 10 between the supporting ribs 6, 7
Are formed.

With this configuration, when a load X due to combustion pressure is applied to the crown surface 1a of the crown portion 1, the crown portion 1
The thrust side and the anti-thrust side are pressed against the piston pin boss portion 4 in the stroke direction of the piston body 1, whereby the support ribs 6 rotate around the piston pin boss portion 4 in opposite directions on the thrust side and the anti-thrust side. Receive moments Y and Z. However, the rotational moments Y and Z due to such a combustion pressure are generated by the support ribs 6,
7, the bases 4a, 4a of the piston pin boss 4
Since the separation surfaces 9 and 10 are formed between the b and the support ribs 6 and 7, the separation surfaces 9 and 10 slide and relatively slide with each other , and the root portions 4 a and 4 a of the piston pin boss portion 4.
4b does not generate tensile stress. Also, in the cylinder
When a lateral force (thrust force) is applied to the piston main body A from the inner wall of the cylinder bore by the reciprocation of the piston , the support ribs 6 and 7 are pressed against the piston pin boss 4 to support the skirt 2. Thus, the function as a supporting rib is sufficiently achieved.

The separating surfaces 9 and 10 may be formed simply as separated as in the above-described embodiment. In particular, when the piston body A is made of a lightweight alloy such as an aluminum alloy, as shown in FIG. , Separated separation surfaces 9 and 10
Then, a reinforcing plate 8 formed of a metal member or resin may be stretched, or a surface treatment with a wear-resistant material may be performed as shown in FIG. In the above embodiment, the separation surfaces 9 and 10 are connected to the bases 4a and 4b of the piston pin boss.
However, the present invention is not limited to this, and the support ribs 6 and 7 may be formed by cutting out the middle part of the support ribs 6 and 7.

[0015]

In the piston for an internal combustion engine according to the present invention having the above-described structure, a separation surface is formed between the piston pin boss portion and the support rib by separating the base portion of the piston pin boss portion from the support rib or the support rib itself. However, when a force due to the combustion pressure acts on the support ribs, a slip occurs on the separation surface from the piston pin boss portion, causing relative sliding , so that no tensile stress is generated at the root of the piston pin boss portion, and
When a lateral force (thrust force) is applied to the piston from the inner wall of the cylinder bore due to the reciprocating motion of the piston in the cylinder, the support rib is pressed against the piston pin boss to support the skirt. result,
The base of the piston pin boss can secure sufficient strength without increasing the wall thickness, and at the same time, achieve a lightweight piston.

[Brief description of the drawings]

FIG. 1 is a front view of a piston for an internal combustion engine employing a first embodiment of the present invention, as seen from a piston hole direction.

FIG. 2 is a perspective view of a portion surrounded by a dashed line circle in FIG. 1 of a piston for an internal combustion engine adopting a second embodiment of the present invention.

FIG. 3 is a perspective view of a portion surrounded by a dashed-dotted line circle in FIG. 1 of a piston for an internal combustion engine employing a third embodiment of the present invention.

[Explanation of symbols]

A Piston body 2 Skirt part 3 Piston pin hole 4 Piston pin boss part 4a Root part 4b Root part 5 Cutout hole 6 Support rib 7 Support rib 9 Separation surface 10 Separation surface

Claims (1)

(57) [Scope of request for utility model registration] 1. The skirt portion is not prone to the piston pin boss.
A punched hole is formed, and the piston pin boss and the
Forming a support rib continuous with the inner peripheral surface of the skirt portion, and
Separate the support ribs and abut against each other
When an axial load due to combustion pressure is applied
A piston for an internal combustion engine, characterized in that a separation surface is formed so as to be relatively slidable .