JPH0649743U - Piston for internal combustion engine - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a piston for an internal combustion engine that can surely relieve stress concentration generated in a pin boss portion even if mass adjustment is performed. A pin boss portion 2 is formed on a skirt portion 1B, and the side of the pin boss portion 2 opposite the crown portion 1A side is formed larger by the mass adjustment allowance of the piston body 1, while the pin boss portion 2 is opposite the crown portion 1A side. On the side, an oil hole 4 communicating with the piston pin hole 3 is formed, the piston pin hole 3 side of the oil hole 4 is formed on the small diameter portion 4a, and the opposite side of the piston pin hole 3 side is formed on the large diameter portion 4b. When the chamfered portion 5 is formed on the inner surface continuous portion of the hole 4 and the position and size of the chamfered portion 5 are cut to the maximum amount L of the mass adjustment allowance of the piston body 1,
It was set so that at least a part of the chamfered portion 5 remained.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 This invention relates to a piston for an internal combustion engine.

[0002]

[Prior art]

 In a piston for an internal combustion engine, a piston main body is composed of a crown portion and a skirt portion, and a pin boss portion having a piston pin hole is formed in the skirt portion. On the side opposite to the crown side of this pin boss, it is necessary to have enough strength to withstand the inertial force of the piston itself, and when an oil hole communicating with the piston pin hole is formed there. Must pay attention to stress concentration around the oil hole. Conventionally, in order to relieve the stress concentration, a chamfered portion is formed on the side opposite to the piston pin hole side of the oil hole (for example, see Japanese Utility Model Laid-Open No. 60-54750).

[0003]

[Problems to be solved by the device]

 However, in the above piston for an internal combustion engine, the opposite side of the crown side of the pin boss is cut to adjust the mass of the piston main body.In this case, all or one of the chamfered portions of the oil hole is cut. There is a risk that the part will disappear and the stress concentration alleviating effect will disappear or it will be diminished.

The present invention has been made in order to solve the above problems, and an object thereof is to provide a piston for an internal combustion engine that can surely relieve stress concentration generated in a pin boss portion even if mass adjustment is performed. .

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, an internal combustion engine piston according to the present invention comprises a piston body having a crown portion and a skirt portion, and a pin boss portion having a piston pin hole formed in the skirt portion. An opposite side of the pin boss portion to the crown side is formed larger by the mass adjustment allowance of the piston body, while an oil hole communicating with the piston pin hole is formed to the opposite side of the pin boss portion to the crown side. Forming a small diameter portion on the piston pin hole side of the oil hole and a large diameter portion on the opposite side to the piston pin hole side, and forming a chamfered portion on the inner surface continuous portion of the oil hole, The position and size of are set so that at least a part of the chamfer remains when the piston body is cut to the maximum amount of the mass adjustment allowance.

[0006]

[Action]

 With the above configuration, the mass adjustment of the piston body is performed by cutting the opposite side of the crown side of the pin boss section.

When the above-mentioned mass adjustment is stopped within the range of the large diameter portion of the oil hole, the chamfered portion remains entirely, so that the stress concentration around the oil hole in the pin boss portion is relieved.

Further, since the opposite side of the oil hole to the piston pin hole side is a large diameter portion and not a chamfered portion, the mass adjustment margin is not reduced more than necessary, and the crown of the pinboss portion is not reduced. It is not necessary to form a chamfer at the opening of the oil hole because a sufficient thickness is secured on the side opposite to the section side.

Even when the mass adjustment reaches the chamfered portion, a part of the chamfered portion remains, so that stress concentration around the oil hole in the pin boss portion is relieved.

[0010]

【Example】

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

FIG. 1 is a front sectional view of a piston for an internal combustion engine in a state in which a piston pin is not attached, viewed in a direction perpendicular to the piston pin hole, and a left half thereof is omitted. FIG. 2 is an enlarged view of FIG. 1 showing a main part of the piston. FIG. 3 is a diagram showing the relationship between the amount of mass adjustment from the opposite end of the pin boss portion from the crown portion side and the maximum value of the generated stress.

The piston body 1 is composed of a crown portion 1A and a skirt portion 1B. A pin boss portion 2 is formed in the skirt portion 1B, and a piston pin hole 3 is formed in the pin boss portion 2. The opposite side of the crown portion 1A side of the pin boss portion 2 is formed to be large by an adjustment allowance (the maximum amount L in the mesh line portion shown in FIGS. 1 and 2) for adjusting the variation of the mass of the piston body 1. There is.

On the opposite side of the pin boss portion 2 from the crown portion 1A side, an oil hole 4 extending in the center line direction of the piston body 1 and communicating with the piston pin hole 3 is formed. The piston pin hole 3 side of 4 is formed in the small diameter portion 4a, and the opposite side of the piston pin hole 3 side is formed in the large diameter portion 4b. A chamfered portion 5 of C0.2 or more is formed on the inner surface continuous portion of the oil hole 4. The position and size of the chamfered portion 5 are slightly more than half the axial length t of the chamfered portion 5 as shown in FIG. 2 when the piston body 1 is cut to the maximum amount L of the adjustment allowance. Is set to remain. The large diameter portion 4b is formed in a straight or tapered cylindrical locate hole.

In the above configuration, the mass adjustment of the piston body 1 is performed by cutting the side of the pin boss portion 2 opposite to the crown portion 1A side.

When the mass adjustment is stopped within the range of the large diameter portion 4b of the oil hole 4, the chamfered portion 5 remains entirely, so that the stress concentration around the oil hole 4 in the pin boss portion 2 is moderated.

Further, since the opposite side of the oil hole 4 to the piston pin hole 3 side is the large-diameter portion 4b and is not a chamfered portion, the mass adjustment margin does not decrease more than necessary. This is an extremely excellent point as can be seen from the fact that the mass adjustment allowance is extremely reduced when the chamfered portion 5 is formed with a continuous chamfered portion instead of the large diameter portion 4b. .

Furthermore, since a sufficient thickness is secured on the side of the pin boss portion 2 opposite the crown portion 1A side, it is not necessary to form a chamfered portion at the opening of the oil hole 4.

Even when the mass adjustment reaches the chamfered portion 5, a part of the chamfered portion 5 remains, so that the stress concentration around the oil hole 4 in the pin boss portion 2 is relieved.

[0019]

[Effect of device]

 As described above, according to the present invention, the piston body is composed of the crown portion and the skirt portion, the pin boss portion having the piston pin hole is formed in the skirt portion, and the pin boss portion is provided on the opposite side of the crown portion side. On the opposite side of the crown portion side of the pin boss portion from the piston body, and an oil hole communicating with the piston pin hole is formed, and the piston pin hole side of the oil hole has a small diameter. Of the piston hole is formed on the side opposite to the piston pin hole to a large diameter portion, and a chamfer is formed on the inner surface continuous portion of the oil hole.The position and size of the chamfer are adjusted to adjust the piston body to the mass. Since it was set so that at least a part of the chamfer remains when cutting to the maximum amount, the mass of the piston body can be easily adjusted by cutting the pin boss opposite the crown side. It is possible.

Further, since at least a part of the chamfered portion can be left by the above-mentioned mass adjustment, stress concentration around the oil hole in the pin boss portion can be surely relieved. In addition, the large diameter part of the oil hole minimizes the reduction of the mass adjustment allowance and prevents the mass adjustment from being hindered, while ensuring a sufficient wall thickness on the opposite side of the crown side of the pin boss. You can Therefore, sufficient strength is secured on the opposite side to the crown side of the pin boss.

[Brief description of drawings]

FIG. 1 is a front cross-sectional view of a piston for an internal combustion engine according to an embodiment of the present invention in a state in which a piston pin is not mounted, as viewed in a direction perpendicular to a piston pin hole, with a left half omitted.

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

FIG. 3 is a diagram showing the relationship between the amount of mass adjustment from the opposite end of the pin boss portion to the crown side and the maximum value of generated stress.

[Explanation of symbols]

 1 Piston body 1A Crown part 1B Skirt part 2 Pin boss part 3 Piston pin hole 4 Oil hole 4a Small diameter part 4b Large diameter part 5 Chamfered part L Maximum amount of mass adjustment allowance

Claims (1)

[Scope of utility model registration request] 1. A piston body is composed of a crown portion and a skirt portion, a pin boss portion having a piston pin hole is formed in the skirt portion, and the opposite side of the pin boss portion from the crown portion side is While increasing the mass adjustment allowance of the piston body, on the side opposite to the crown side of the pin boss, an oil hole communicating with the piston pin hole is formed, and the piston pin hole side of the oil hole is a small diameter part, The opposite side of the piston pin hole side is formed in a large diameter portion, and the chamfered portion is formed in the inner surface continuous portion of the oil hole, and the position and size of the chamfered portion are set to the piston main body in the mass adjustment allowance. A piston for an internal combustion engine, characterized in that it is set so that at least a part of the chamfer remains when cutting to the maximum amount.