JP2581318Y2 - Piston for internal combustion engine - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION This invention relates to a piston for an internal combustion engine of an automobile or the like.

[0002]

2. Description of the Related Art Conventionally, there is a piston for an internal combustion engine described in Japanese Utility Model Laid-Open No. 58-163652. In this piston, as shown in FIGS. 6 and 7, a hole 1 serving as an oil passage is
The lubricating oil scraped from the cylinder bore by the oil ring during operation of the engine is supplied to the piston pin hole 15 through the oil ring groove 14 and the upper hole 13a. Is discharged from the lower hole 13b to the outside of the piston pin hole 15.

[0003] The lower hole 13b is a through hole having a role of creating a flow of lubricating oil together with the upper hole 13a, and has a small diameter. The lower hole 13b is commonly used for automatic conveyance of the piston main body 11 in an automatic engine assembly line, and a support pin is inserted when the piston main body 11 is conveyed.

[0004]

However, in the conventional piston for an internal combustion engine described above, since the lower hole 13b is formed in the through hole, the lower strength of the pin boss portion 12 is reduced, and the durability may be reduced. There is. In addition, since the lower hole 13b is formed to have a small diameter in order to avoid this reduction in strength, it is difficult to insert a support pin into the lower hole 13b.

The present invention has been made in order to solve the above-mentioned problem, and it is possible to easily insert a support pin while securing a necessary strength below a pin boss portion, and to provide an internal combustion engine capable of responding favorably to an automatic engine assembly line. An object of the present invention is to provide an engine piston.

[0006]

In order to achieve the above-mentioned object, only a lower end of the pin boss is opened below the pin boss to form a pin insertion hole into which a support pin for transporting the piston body is inserted. And, on the inner wall of the piston pin hole,
A relief groove is formed along the axial direction of the piston pin hole .

[0007]

According to the above construction, the required lower strength of the pin boss is ensured irrespective of the formation of the pin insertion hole, and the diameter of the pin insertion hole is made larger than in the prior art so that the support pin can be easily inserted. It becomes possible.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1A is a longitudinal sectional view showing a piston for an internal combustion engine according to a first embodiment of the present invention, and FIG. 1B is an enlarged view of a part A of FIG.

In FIG. 1, reference numeral 1 denotes a piston body, which comprises a crown 2 and a skirt 3. The skirt portion 3 is provided with a pin boss portion 4, a piston pin hole 5 is formed in the pin boss portion 4, and a piston pin (not shown) is fitted into the piston pin hole 5.

The pin boss portion 4 is provided below the pin boss portion 4.
A pin insertion hole 6 opening only at the lower end of the
A support pin (not shown) for transporting the piston body can be inserted into the pin insertion hole 6.

The pin insertion hole 6 has a cylindrical shape as shown in FIG. 1, but is not limited to this. For example, a large opening at the lower end of the pin boss 4 is shown in FIGS.
May be as shown in FIG. Pin insertion hole ₆₁ shown in FIG. 2 from the open end to the bottom shallow depth a larger diameter and the same diameter, the bottom is formed flat. A tapered surface gradually decreasing diameter in accordance with the pin insertion holes 6 ₂ shown in FIG. 3 from the open end to substantially axial intermediate portion is directed toward the bottom side, in the axial direction substantially the same diameter from the middle portion to the bottom end, is the bottom Each is formed on a conical surface. Further, the tapered surface gradually decreases in diameter in accordance with the pin insertion hole 6 ₃ open end shown in FIG. 4 until substantially axial intermediate portion is directed toward the bottom side, to the bottom end in the axial direction substantially intermediate site is the bottom of the same diameter It is formed flat.

[0012] The pin insertion hole 6,6 _1, 6 _2, 6 _3,
When the pin boss portion is not provided, the pin boss portion has a depth H that can secure a thickness t (a portion shaded in FIG. 5) in a region where the strength is less reduced than the strength obtained below the pin boss portion 4. 4 is formed at a position where a required strength can be secured.

In the upper portion of the pin boss portion 4, a communication hole 7 is formed, one end of which is opened in the piston pin hole 5 and is inclined with respect to the axial direction of the piston pin. The other end of the communication hole 8 extending in the axial direction of the piston pin, one end of which is opened at the bottom of the groove 7 is connected.
On the inner wall of the piston pin hole 5, a relief groove 9 is formed along the axial direction of the piston pin hole 5. During operation of the engine, lubricating oil scraped from the cylinder bore into the oil ring groove 10 by an oil ring (not shown) is supplied to the piston pin hole 5 through the communication holes 7 and 8, and the lubricating oil after lubrication of the piston pin is relieved. The gas is discharged to the outside of the piston pin hole 5 through the groove 9.

In the above configuration, the pin insertion hole 6,
6 ₁ , 6 ₂ , and 6 ₃ are not through holes and cannot be used for discharging lubricating oil. However, the relief groove 9 can sufficiently cope with the discharging of lubricating oil after piston pin lubrication. There is no.

Furthermore, the pin insertion holes 6, 6 _1, 6 _2, 6 ₃ are opened only at the lower end of the pin boss portion 4, since it is not a through hole, to secure the lower strength required pin boss portion 4 can be, and pin insertion holes 6,6 _1, 6 _2, 6 ₃ diameter of a larger diameter than the conventional, easily inserted a support pin which is used in the automatic conveyance of the piston body 1 of the engine automatic assembly line, and wherein The support stability of the piston main body 1 by the support pin can be improved.

[0016]

As described above, according to the present invention, a pin insertion hole is formed at the lower portion of the pin boss portion, which is opened only at the lower end of the pin boss portion, into which a support pin for transporting the piston body is inserted. Since the insertion hole is not a through-hole, the diameter of the pin insertion hole can be made larger than before while securing the necessary lower strength for the pin boss, and this allows the piston body to be transported in the automatic engine assembly line. By facilitating the insertion of the used support pins and improving the support stability of the piston body by the support pins, it is possible to cope well with an automatic engine assembly line.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a piston for an internal combustion engine according to a first embodiment of the present invention. (2) It is the A section enlarged view of (1).

FIG. 2 is a sectional view corresponding to FIG. 1 (2) showing a piston for an internal combustion engine according to a second embodiment of the present invention.

FIG. 3 is a sectional view corresponding to FIG. 1 (2) showing a piston for an internal combustion engine according to a third embodiment of the present invention.

FIG. 4 is a sectional view corresponding to FIG. 1 (2) showing a piston for an internal combustion engine according to a fourth embodiment of the present invention.

FIG. 5 is a graph showing a relationship between a lower strength of a pin boss portion and a lower thickness t.

FIG. 6 is a sectional view showing a conventional piston for an internal combustion engine.

FIG. 7 is a cross-sectional view showing another conventional internal combustion engine piston.

[Explanation of symbols]

1 piston body 4 pin boss portions 6 _1, 6 _2, 6 ₃ pin insertion hole

Claims (1)

(57) [Scope of request for utility model registration] A pin insertion hole formed at a lower portion of the pin boss portion to open only a lower end of the pin boss portion, into which a support pin for transporting a piston body is inserted ;
On the inner wall, a relief groove along the axial direction of the piston pin hole
A piston for an internal combustion engine, wherein a piston is formed .