JP2592985Y2 - Piston cooling system - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION This invention aims to improve the cooling of a casting piston for an internal combustion engine by improving the space around a cooling oil in a piston cooling cavity at the head.

[0002]

2. Description of the Related Art Generally, in a casting-type piston, a core a (see FIG. 3) for forming a cooling cavity in the piston head is formed by four leg pieces b, c, d, and 4 when casting the piston.
In order to support the buoyancy of the core at the time of casting, these leg pieces b to e are required to be symmetrically arranged and to have a size as large as possible.

[0003] As a result, the cast f includes the core a
A cooling cavity g is formed at the position where is placed, and four through holes h, i, j and k are formed below the cooling cavity g and open at positions where the leg pieces be are provided.

[0004] Of these through holes h to k, the through hole h is used as an inlet for cooling oil, and as shown in FIGS. The cooling oil ejected from the injection means is supplied to the cooling cavity g, and the cooling oil is discharged from the through hole k as an outlet while cooling the head of the piston f.

[0005]

However, in practice, the flow of the cooling oil in the cooling cavity g is as shown in FIG. 6 and the cooling oil supplied from the through hole h to the cooling cavity g in both directions. Most of the oil is discharged from the next through holes i and k, so that the cooling oil does not sufficiently pass through the section from the through hole i to the through hole j to the through hole k. However, due to poor cooling of the piston head in this part, the seizure of the piston itself may occur, and in particular, the piston moves violently up and down in the cylinder. From the request, increase the through hole,
As the cross-sectional area of the cooling oil outlet increases, the tendency of insufficient cooling further increases.

[0006]

SUMMARY OF THE INVENTION Here, the present invention is directed to a cooling oil inlet / outlet for the annular cooling cavity of the piston head as described above, and a leg for holding the cooling unit cavity forming core during casting of the piston. In the case of using four through-holes formed by the pieces, the positions of two through-holes adjacent to the through-hole serving as the inlet of the cooling oil among these through-holes are set to the through-hole serving as the inlet. It is proposed to be as close as possible and have a relatively small cross-sectional area.

[0007]

In the piston cooling device according to the first aspect, the cooling oil supplied from the through hole serving as the inlet of the cooling drawer first collides with the ceiling in the cooling cavity and flows along the ceiling. After traveling a distance, it travels downward along the outer wall, with two through holes adjacent to the through hole serving as the entrance as close as possible to the through hole of the entrance. Since the target has a small cross-sectional area, most of the cooling oil passes through these two through-holes and is discharged from the adjacent outlet through-hole,
This achieves improved cooling of the piston head.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment shown in FIGS. 1 and 2, out of four through holes 10 to 13 opening into a cooling cavity 9 formed in a piston head 8, a through hole 1 serving as an inlet for cooling oil is provided.
With respect to the through holes 11 and 13 adjacent to 0, these are positioned as close as possible to the through hole 10 and the cross-sectional area is made relatively small. The imaginary line in the figure is 4
The position and shape of the through holes 11 and 13 when two through holes 10 to 13 are provided completely symmetrically.

In this example, the flow of the cooling oil is:
The cooling cavity 9 enters the cooling cavity 9 through the through hole 10 and collides with the ceiling of the cooling cavity 9 in FIG. Arrows F1 and F2 that progress further
Take the pattern.

That is, if the through holes 11 and 13 are formed as shown in FIG.
In the conventional position as shown by the imaginary line, since these through holes 11 and 13 are located exactly at the position where the oil flows down the wall, cooling oil is discharged from these through holes 11 and 13. However, in this invention, the through hole 10
Through holes 11 and 1 closer to
3 (shown by a solid line in FIG. 2) is open, so that the cooling oil flows down at a position passing through these through holes 11 and 13,
Therefore, the leakage of the cooling oil can be suppressed as much as possible.

The through-holes 11 and 13 are as close to the through-hole 1 as possible.
Although it is close to zero, it is necessary to keep it within a range where there is no problem in strength because it is the part that receives the thrust force of the piston. In addition, the total area of the four through holes is to ensure the minimum that the leg piece supports the buoyancy of the core, and, in terms of balance, the through holes 10, 12> the through holes 11, 13.

[0012]

According to the device having the above structure according to the present invention,
The cooling oil can be spread over the entire area of the cooling cavity formed in the piston head, so that the piston head can be effectively cooled and the occurrence of inconvenience due to insufficient cooling is prevented. An effect that can be obtained is obtained.

[Brief description of the drawings]

FIG. 1 is a bottom view of a main part of an embodiment of the device of the present invention.

FIG. 2 is a perspective view showing the state of circulation of cooling oil in the example shown in FIG.

FIG. 3 is a perspective view showing a core on which a cooling cavity is to be formed.

FIG. 4 is a sectional view of a piston head provided with a conventional cooling device.

FIG. 5 is a cross-sectional view of a conventional example, and is a cross-sectional view taken along line AA of FIG.

FIG. 6 is a perspective view showing a state of circulation of cooling oil in a cooling cavity of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piston head 2 Cooling cavity 10, 11, 12, 13 Through hole

Claims (1)

(57) [Scope of request for utility model registration] An inlet / outlet for cooling oil to / from an annular cooling cavity in a piston head utilizes four through holes formed by legs holding the core for forming a cooling portion cavity during casting of a piston. in which, the positions of the two holes that Tonariru the inlet and comprising through holes of the cooling oil of these holes, pre-filled
Close as close as possible to the through-hole and compare its cross-sectional area
A cooling device for the piston, which is very small .