JP3548369B2 - Internal combustion engine piston - Google Patents

Description

[0001]
TECHNICAL FIELD The present invention relates to a piston of an internal combustion engine in which a cooling cavity is formed by a support for supporting a soluble core .
[0002]
[Prior art]
Among pistons for internal combustion engines, some pistons for diesel engines, which have a large heat load, have a cooling cavity formed inside the piston, and are cooled by introducing cooling oil into the cooling cavity.
[0003]
The cooling cavity is disposed at a predetermined position in a casting mold in a state where the soluble core forming the cooling cavity is supported by a plurality of supports, and a molten metal is injected into the casting mold to remove a piston material. After casting, it is formed by dissolving and removing the soluble core. Further, the support of the soluble core forms a supply / discharge passage of cooling oil communicating with the cooling cavity in the piston material. Note that a similar configuration is described in, for example, JP-A-2-123260.
[0004]
[Problems to be solved by the invention]
However, in the conventional example, the support is provided substantially vertically at a predetermined position of the casting mold.
[0005]
For this reason, when trying to increase the volume of the combustion chamber provided at the crown of the piston, the inner wall of the combustion chamber approaches the support, so that the wall thickness of the piston near the support becomes thin, and the strength of the piston decreases. There is a risk of doing so.
[0006]
The present invention has been devised in view of the above conventional circumstances, without the thickness of the piston is reduced in the support near its object to provide a piston stable strength with an internal combustion engine Tei Ru.
[0007]
[Means for Solving the Problems]
Therefore, the present invention provides a combustion chamber recessed in a crown, a cooling cavity annularly provided so as to surround the combustion chamber, and a plurality of cooling oil supply / discharge passages communicating with the cooling cavity. in a piston for an internal combustion engine provided with the supply and discharge passage, the center line is formed by tilting the outer peripheral side of the piston, and, are the structure in which the so that is formed in a substantially truncated conical shape.
[0008]
According to a second aspect of the present invention, there is provided a combustion chamber recessed in a crown portion, a cooling cavity annularly provided so as to surround the combustion chamber, and a plurality of cooling oils communicating with the cooling cavity. In a piston of an internal combustion engine provided with a supply / discharge passage, the supply / discharge passage is formed by cutting the center line to be inclined toward the outer peripheral side of the piston and cutting the tip so as to be tapered. It has a configuration.
[0013]
Here, the support is inclined so that the distal end is located near the outer periphery of the piston, and the soluble core is supported at the distal end of the support. Specifically, a concave surface along the outer peripheral shape of the soluble core is formed at the tip of the support, and is supported by the concave surface, or a locking pin is provided at the tip of the support. It is possible to support the locking pin by inserting it into a locking hole formed in the soluble core, or to employ both.
[0014]
In addition, a cyclic salt core can be used as the soluble core.
[0015]
In the present invention, the piston for the internal combustion engine is obtained as follows. That is, the support is provided at a predetermined position of the casting mold. By supporting the soluble core at the tip of the support, the soluble core is arranged at a predetermined position in the casting mold. . Preferably, the soluble core is disposed at a position where a crown of a piston is formed, and in this state, a molten metal is poured into the casting mold to cast a piston material. At this time, the soluble core is cast in the piston material. After the casting step, the casting mold is removed, the piston material is taken out of the casting mold, and the soluble core is dissolved and removed with water or the like to form a cooling cavity inside the piston material. When the support is removed from the piston material, a cooling oil supply / discharge passage communicating with the cooling cavity is formed in the piston material. Thereafter, machining is performed on a predetermined position of the piston material to obtain a piston for an internal combustion engine.
[0016]
Here, the support of the soluble core is inclined so that the tip side is located near the outer periphery of the piston. For this reason, even if a large-volume combustion chamber is formed in the crown of the piston, the thickness between the combustion chamber and the supply / discharge passage of the cooling oil formed by the support does not become thin.
[0017]
Therefore, a support of a soluble core can be obtained that does not reduce the thickness of the piston in the vicinity of the support and can obtain a piston for an internal combustion engine having a stable strength.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0019]
FIG. 1 is a perspective view showing a support of a soluble core according to an embodiment of the present invention, together with a casting mold and a soluble core. FIG. 2 is a perspective view of a soluble core supported by the support shown in FIG. 3 is a sectional view showing a state where the piston is arranged at a predetermined position. FIG. 3 is a sectional view showing a main part of a piston obtained in the casting mold shown in FIG.
[0020]
In the figure, reference numeral 1 denotes a casting mold for casting a piston 2, and this casting mold 1 is composed of an outer mold 3A and a mold core 3B.
[0021]
Reference numeral 4 denotes a soluble core. The soluble core 4 forms a cooling cavity 5 at a predetermined position of the piston 2. The soluble core 4 is a cyclic salt core having a salt as a main component.
[0022]
Reference numeral 6 denotes a support for supporting the soluble core 4. The support 6 is implanted at a predetermined position of the mold core 3B. In this embodiment, two supports 6 are arranged at symmetric positions. The support 6 is formed in the shape of a truncated cone, and its center line C is inclined toward the outer peripheral side of the piston 2 so that the tip contacting the soluble core 4 has the outer periphery of the piston 2 as best shown in FIG. It is located on the side. A concave surface 7 is formed at the tip of the support 6 in contact with the soluble core 4 so as to be curved along the outer peripheral shape of the soluble core 4. The concave surface 7 stabilizes the soluble core 4. And can be held. A locking pin 8 is provided at the tip of the support 6, and the locking pin 8 is engaged with a locking hole 9 formed in the fusible core 4 to position the fusible core 4. Is performed conveniently.
[0023]
In the present invention, the piston 2 for an internal combustion engine is obtained as follows. That is, the mold core 3B is arranged in the outer mold 3A, and the casting mold 1 is formed as a whole. The support 6 is provided at a predetermined position of the mold core 3 </ b> B. By supporting the soluble core 4 at the tip of the support 6, the soluble core 4 is positioned at a predetermined position in the casting mold 1. Will be placed. The disposing position of the soluble core 4 is a position where the crown 2a of the piston 2 is formed. In this embodiment, the dissolving core 4 is disposed so as to surround the combustion chamber 10 recessed in the crown 2a of the piston 2. (See FIG. 2).
[0024]
The support of the soluble core 4 by the support 6 stably supports the outer periphery of the soluble core 4 by the concave surface 7 formed at the tip of the support 6 and the support provided at the tip of the support 6. This is performed by inserting a locking pin 8 into a locking hole 9 formed in the soluble core 4.
[0025]
A wear ring 12 is provided at a predetermined position of the casting mold 1, that is, at a position where the piston ring groove 11 of the piston 2 is formed, so as to be cast in the piston material.
[0026]
Next, a molten metal such as an aluminum alloy is poured into a casting mold 1 in which the soluble core 4 is disposed via a runner (not shown) to cast a piston material. At this time, the soluble core 4 is cast in the piston material. The wear ring 12 is also cast-in.
[0027]
After the casting process, the piston material is removed from the casting mold 1. That is, the piston core material is removed from the casting mold 1 by removing the mold core 3B together with the support 6 and removing the outer mold 3A. At this time, the support 6 stops supporting the soluble core 4, separates from the soluble core 4, and is removed from the piston material, thereby forming a supply / discharge passage 13 for cooling oil in the piston material. Will be.
[0028]
Next, water or the like is injected from the supply / discharge passage 13 to dissolve and remove the soluble core 4. Thereby, the cooling cavity 5 is formed inside the piston material, and the cooling cavity 5 communicates with the supply / discharge passage 13.
[0029]
Thereafter, machining is performed on a predetermined position of the piston blank. That is, the crown surface 2b and the body 2c are machined, and the piston ring grooves 11, 14, and 15 are formed. Further, a piston pin hole and the like (not shown) are machined. Thus, the internal combustion engine piston 2 is obtained (see FIG. 3).
[0030]
When the internal combustion engine piston 2 is used by being incorporated in an internal combustion engine (not shown), the cooling oil guided from the supply / discharge passage 13 is cooled by circulating in the cooling cavity 5.
[0031]
Here, the support 6 of the soluble core 4 is inclined so that the tip end is located near the outer periphery of the piston 2. For this reason, even if a large-volume combustion chamber 10 is formed in the crown 2 a of the piston 2, the thickness between the combustion chamber 10 and the cooling oil supply / discharge passage 13 formed by the support 6 is thin. Never be.
[0032]
Therefore, the support 6 of the soluble core 4 is obtained in which the piston 2 for the internal combustion engine having a stable strength can be obtained without the thickness of the piston 2 becoming thin near the support 6.
[0033]
FIG. 4 is a view showing another embodiment of the present invention, which is different from the above-described embodiment. It is a shape that has been shaved off so that the side is tapered. Since other configurations are the same as those of the above-described embodiment, the same components are denoted by the same reference numerals, and redundant description will be omitted.
[0034]
In this case, the support 6 is arranged so that the horseshoe-shaped surface 6a that has been scraped off faces the center line side of the piston 2. As a result, the center line C of the support 6 is inclined toward the outer peripheral side of the piston 2.
[0035]
With such a configuration, the same operation and effect as described in the above embodiment can be obtained.
[0036]
Although the embodiments have been described with reference to the drawings, the specific configuration is not limited to the embodiments and can be changed without departing from the spirit of the invention. For example, the embodiment in which two support members 6 are provided has been described, but the provision of three or more support members is optional.
[0037]
【The invention's effect】
As described above in detail, according to the present invention, the without the thickness of the piston is reduced in support vicinity can be obtained piston stable strength with an internal combustion engine and that Do.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a support of a soluble core together with a casting mold and a soluble core according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a state where a soluble core supported by a support shown in FIG. 1 is arranged at a predetermined position in a casting mold.
FIG. 3 is a drawing showing a cross section of a main part of a piston obtained in the casting mold shown in FIG. 2;
FIG. 4 is a perspective view of a support for a soluble core showing another embodiment of the present invention.
[Explanation of symbols]
Reference Signs List 1 casting die 2 piston 3A outer die 3B die core 4 soluble core 5 cooling cavity 6 support 7 concave surface 8 locking pin 9 locking hole 10 combustion chamber 13 supply / discharge passage C center line

Claims (2)

A combustion chamber recessed in the crown,
A cooling cavity annularly provided so as to surround the combustion chamber;
A plurality of cooling oil supply and discharge passages communicating with the cooling cavity,
In the piston of the internal combustion engine provided with
A piston for an internal combustion engine, wherein the supply / discharge passage is formed such that a center line is inclined toward an outer peripheral side of the piston and is formed in a substantially truncated cone shape. A combustion chamber recessed in the crown,
A cooling cavity provided annularly so as to surround the combustion chamber;
A plurality of cooling oil supply and discharge passages communicating with the cooling cavity,
In the piston of the internal combustion engine provided with
A piston for an internal combustion engine, wherein the supply / discharge passage is formed such that a center line is inclined toward an outer peripheral side of the piston, and is formed by cutting so that a tip is tapered .

Images