JP3049923B2 - 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 a piston for an internal combustion engine.

[0002]

2. Description of the Related Art Various types of conventional pistons for internal combustion engines have been proposed. For example, it is described in "Esthema Emina New Model Vehicle Description" issued on January 13, 1992 by Toyota Motor Corporation. In the piston 70 for an internal combustion engine shown in FIG. The top surface 72 and the ring groove 73 are cooled. Here, the oil is ejected from an unillustrated oil jet, and a notch 75 is provided in the skirt portion 74 to prevent interference between the oil jet and the piston 70. In addition, the skirt 7
In a substantially upper portion of the base 4 and in the pin boss portion 76, an iron thermal expansion suppressing strut 77 continuous in the circumferential direction is cast.

[0003]

However, the above-described prior art piston 70 for an internal combustion engine has a problem that the rigidity of the skirt 74 is reduced around the notch 75 due to the presence of the notch 75. I have. For example, when the piston 70 moves up and down in a cylinder (not shown), the piston 70 receives a side pressure from the left and right that tends to deform the piston 70. Therefore, if the rigidity of the skirt portion 74 is low, the piston 70 deforms immediately. I will.

In a piston manufactured by high-pressure casting, a rib or the like cannot be provided at the lower end of the skirt portion 74. If the thickness of the skirt portion 74 is increased in order to compensate for the reduction in rigidity, it is difficult to reduce the draft. The skirt portion 74 becomes unnecessarily thick as it approaches the skirt shoulder.
Therefore, the weight of the piston 70 increases, the inertia force increases, and there are problems such as an increase in engine size and a decrease in output performance.

Accordingly, it is an object of the present invention to provide a piston for an internal combustion engine having a notch in a skirt portion, while suppressing an increase in weight and preventing a decrease in rigidity of the skirt portion.

[0006]

Configuration of the Invention

[0007]

According to the technical means of the present invention taken to solve the above-mentioned technical problem of the present invention, a top surface portion, a ring groove portion, a land portion, and a pin hole are respectively formed.
Provided between a pair of pin bosses and pin bosses, at least
Also a pair of skirt <br/> isolation portion notched on one of the lower end is formed, and the piston for an internal combustion engine having a cast wrapped struts each skirt substantially in the upper part and in each pin boss portion, the strut, Skirt near notch
Extending vertically from the upper part to the lower end side.
The skirt is provided with an extension that is cast in the skirt,
Is to ensure the rigidity of the skirt portion where the skirt portion is formed .

[0008]

SUMMARY OF According to the technical means of the present invention described above, Stra
Rigidity near the notch in the skirt due to the extension of the cut
The skirt is not thickened.
This makes it possible to compensate for the decrease in rigidity of the skirt.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying the technical means of the present invention will be described below with reference to the accompanying drawings.

1 and 2, a piston 10 for an internal combustion engine includes a top surface 11, a ring groove 12, a land 1
3. A pair of pin boss portions 1 each having a pin hole 18 formed therein
4, provided between the pin bosses 14 and cut out at one lower end
And a strut 17 continuously and circumferentially cast in the upper portion of the skirt portion 15 and the pin boss portion 14. The notch 16 is formed to prevent interference with an oil jet (not shown), and oil is injected toward the inner peripheral surface of the piston 10 by the oil jet, thereby
Is cooled.

The strut 17 has a curved portion 19 that curves so as to bypass a pin hole 18 formed in the pin boss portion 14.
And the skirt 2 near the notch 16.
(2) extending vertically from the upper part toward the lower end
The skirt portion 22 is provided with an extending portion 20 that is cast in the skirt portion 22.
The rigidity of the skirt portion 22 where the notch 16 is formed
Is secured . Here, in order to increase the reinforcing force, it is desirable that the extending portion 20 has a rib 21 that is convex toward the outer peripheral surface side of the piston 10 continuously in the vertical direction as shown in FIGS. .

FIG. 5 (a) shows the difference in rigidity between the notched side and the non-notched side of the conventional piston shown in FIG. 6, and FIG. 5 (b) shows the piston 10 of the present embodiment. 3 shows the difference in rigidity between the side with the notch and the side without the notch. As is clear from both figures, it can be seen that the conventional piston has an imbalance in rigidity on both sides and is disadvantageous to the behavior of the piston. However, in the piston 10 of the present embodiment, the extending portion 20 of the strut 17 is notched. The rigidity on both sides is balanced to compensate for the decrease in rigidity due to

[0013]

As described above, in the piston for an internal combustion engine according to the present invention, the strut is provided with a skirt near the notch.
Extending vertically from the upper part to the lower end side.
Since the extending portion cast in the skirt portion is formed, the rigidity of the skirt portion due to the cutout can be compensated without increasing the thickness of the skirt portion. Therefore,
In addition to suppressing the increase in the weight of the piston, it is possible to prevent deformation of the piston due to a decrease in rigidity, occurrence of a tapping sound due to the deformation, reduction in engine output, and the like.

[Brief description of the drawings]

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

FIG. 2 shows a bottom view in FIG.

FIG. 3 shows a side view of the strap in FIG.

FIG. 4 shows a top view of the strap in FIG.

5 (a) shows the difference in rigidity between the notched side and the non-notched side in the prior art piston shown in FIG. 6, and FIG. 5 (b) shows the cut in the piston shown in FIG. The difference in rigidity between the side with a notch and the side without a notch is shown.

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

[Explanation of symbols]

 Reference Signs List 10 piston for internal combustion engine, 11 top surface part, 12 ring groove part, 13 land part, 14 pin boss part, 15 skirt part, 16 notch, 17 strut, 20 extension part.

Claims (1)

(57) [Claims] 1. A top wall, a ring groove, a land portion, respectively Pi
A pair of pin boss portions having a hole formed between the pin boss portions.
Provided, with a notch formed at least at one lower end
A pair of skirt portions being, and in the piston for an internal combustion engine having the wrapped cast to each skirt portion substantially upper part and in the respective pin boss portions strut, said strut
In the vicinity of the cutout,
And extend vertically toward the lower end side.
The notch is formed by providing an extended portion that is cast
A piston for an internal combustion engine, wherein the rigidity of the skirt portion is ensured .