JP2591811Y2 - Internal combustion engine piston - 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 having a cooling cavity for circulating cooling oil, and more particularly to a piston of an internal combustion engine which can maintain a high cooling efficiency and is excellent in productivity.

[0002]

2. Description of the Related Art In recent engines, the amount of heat generated increases with an increase in output, and a large heat load is applied to a piston ring, which tends to cause seizure. Therefore, for the purpose of cooling these piston rings, a cooling cavity 3 for circulating cooling oil is formed in a thick portion inside the ring groove 2 of the piston 1 as shown in FIGS. 6 and 7. Things are used.

The piston 1 has an introduction hole 5 for introducing cooling oil injected from an oil jet into the cooling cavity 3.
And a discharge hole 6 which circulates through the cooling cavity 3 and discharges the cooling oil having absorbed the heat of the piston 1 to an oil pan below the piston 1. When casting a piston 1 of this type, a core (usually a salt core) is used to form the cooling cavity 3 as proposed in, for example, JP-A-2-123260. The mold is set so that the portion of the support rod protruding from the support for supporting the core becomes the introduction hole 5 and the discharge hole 6.
In addition, at least one, preferably about two more support rods are used to stably support the core.

[0004] After the additional support rod is die-cut, a leakage hole 7 is formed so as to communicate from the cooling cavity 3 to the inside of the skirt portion 4 of the piston 1, and the leakage hole 7 is opened. A washer 9 having a pin hole 8 opened is cast into a portion where the pin hole 8 is formed, and is integrally formed. In this way, the cooling oil circulating in the cooling cavity 3 from the introduction hole 5 toward the discharge hole 6 leaks from the leak hole 7 to the oil pan through the pin hole 8 opened in the washer 9. It will leak out, compared to the case where this washer 9 is not cast,
We try to reduce the amount of leakage.

[0005]

On the other hand, when the engine is under a high load, the temperature of the engine rises, and the viscosity of the engine oil decreases, resulting in a smooth state. Since the reciprocating speed of the piston increases as the height increases, the piston vibrates up and down violently.

Therefore, when the piston described in the above publication is used in such a state, the amount of the cooling oil whose viscosity has decreased is shaken down from the pin hole while the piston is swung up and down. However, there is a problem that as the engine temperature and the number of revolutions increase, it becomes increasingly difficult to obtain a sufficient cooling effect. In view of the above problems, the present invention provides a cooling system that enters the cooling cavity through the introduction hole even when the engine is used at a high engine temperature and high rotational speed, such as when the engine is operated under a high load. An object of the present invention is to provide a piston of an internal combustion engine that does not leak from a core support portion at all until oil falls from a discharge hole and can always maintain high cooling efficiency. .

[0007]

In order to achieve the above object, a piston of an internal combustion engine according to the present invention has an annular cooling cavity formed inside a ring groove of the piston and an inside of a skirt portion of the cooling cavity. In a piston having an introduction hole and a discharge hole for communicating cooling oil, a core forming the cooling cavity is formed at the time of casting of the piston, and a part of the introduction hole, the part of the discharge hole, and other parts are supported by a support. Support and guide
Wherein in the portion of the discharge hole and Nyuana, while supporting directly to the support, in other parts, and supported by interposing between the plug and the core and the support body, said plug washer
And a concave or convex portion formed on the core side of the washer.
One fitting portion and a concave portion or a convex portion formed on the support side.
A second fitting portion, the first fitting portion and the second fitting portion
A protrusion or recess formed in the core and a support
Fit each to the formed convex or concave, the core
The piston is formed by supporting and plugging the plug integrally with the piston.

The plug is preferably made of the same material as the material of the piston (for example, aluminum when the piston is made of aluminum) and integrated with the plug cast into the piston. In this case, it is preferable to use a material having a coefficient of thermal expansion close to that of the piston and having a higher melting point than the piston.

Further, the first fitting portion and the second fitting portion need only be fitted with concave portions or convex portions of the core and the support so as to stabilize the position of the core during casting. Yes, it is usually preferable to form them as protrusions or recesses.

[0010]

[Operation] The piston of the internal combustion engine of the present invention has the above-described structure. When the piston is cast, the first fitting portion and the second fitting portion of the plug each form a core forming a cooling cavity. And the recesses or protrusions provided on the support for supporting the core can be fitted to the core so that the core can be stably supported by the support. It acts to close the core support that communicates with the inside of the part.

[0011]

Next, an embodiment in which the present invention is applied to a conventional example shown in FIG. 6 will be described with reference to the drawings. In the piston 1 according to the first embodiment shown in FIG. 1, a cooling cavity 3 for circulating cooling oil is formed in a thick portion of the piston inside the ring groove 2. The piston 1 has an introduction hole 5 for introducing cooling oil injected from an oil jet into the cooling cavity 3, and is introduced from the introduction hole 5 to circulate through the cooling cavity 3 while absorbing heat of the piston 1. A discharge hole 6 for discharging the cooling oil to be discharged to an oil pan below the piston 1 is formed.

Further, at the time of casting the piston 1, at the portion where the support for supporting the core for forming the cooling cavity 3 is provided, after the die is cut, the portion other than the introduction hole 5 and the discharge hole 6 is provided. A core support 7 communicating with the cooling cavity 3 from the inside of the skirt 4 of the piston 1 is formed. When the piston 1 of FIG. 1 is cast, as shown in FIG. 2, the second fitting portion 33 (the projection in this case) of the plug 31 is fitted into the concave portion 22 formed in the support body 21 so that the plug 31 is It is arranged so as not to fall from the support body 21, and further, the first fitting portion 32 (the projection in this case) of the plug 31 is fitted into the concave portion 12 formed in the core 11 to stabilize the core 11. And place it to support it.

As shown in FIG. 2, by arranging the support 21, the plug 31, and the core 11 and casting, the plug 31 for closing the core support 7 is cast as shown in FIG. Since the inserted piston 1 is formed and the core support portion 7 is completely closed by the washer 34 of the plug 31, no cooling oil leaks from the core support portion 7 below the piston 1 and there is no introduction hole. 5 ensures that the entire amount of cooling oil introduced into the cooling cavity 3 circulates to the discharge hole 6.

Next, in Embodiment 2 shown in FIG.
The second fitting portion 33 (the concave portion in this case) of the plug 31 is fitted into the convex portion 23 formed on the support member 21, and the plug 31 is arranged so as not to drop from the support 21. The first fitting portion 32 (the projection in this case) of the plug 31 is fitted into the recess 12 thus formed, and is arranged so as to stably support the core 11 as described above. By casting the piston 1 in this manner, the same effect as that of the first embodiment can be obtained.

On the other hand, in Embodiment 3 shown in FIG.
The second fitting portion 33 (the protrusion in this case) of the plug 31 is fitted into the concave portion 22 formed on the core 11, and further, the convex portion 13 formed on the core 11 is formed.
The first fitting portion 32 (the concave portion in this case) of the plug 31 is fitted to the plug 31, and the core 11 is arranged to be supported by the support 21 as described above. In the case of this embodiment, the first fitting portion 32 of the plug 31 does not protrude into the cooling cavity 3, so that the inside of the cooling cavity 3 is different from the cases of the first and second embodiments. The effect of reducing the flow resistance of the circulating cooling oil is also obtained.

The embodiment 4 shown in FIG.
The two second fitting portions 33 (the concave portions in this case) of the plug 31 are fitted into the two convex portions 23 formed on the core 11, respectively, and the plugs 31 of the plug 31 are fitted into the convex portions 13 formed on the core 11. One fitting portion 32 (in this case also a concave portion) is fitted. In any case where the piston 1 is cast according to any of the embodiments described above, the core 11 can be stably supported by the support 21 at the time of casting. The communicating core support 7 can be completely closed. The shapes of the first fitting portion 32 and the second fitting portion 33 of the plug 31 are not particularly limited, but the shape should be such that the resistance of the cooling oil circulating in the cooling cavity 3 does not become as large as possible. It is preferred.

[0017]

The piston of the internal combustion engine according to the present invention has an annular cooling cavity formed inside the ring groove of the piston, a cooling oil introduction hole communicating with the inside of the skirt portion of the cooling cavity, and a discharge hole. In the piston having the above structure, at the time of casting the piston, the core forming the cooling cavity is supported by a support at the portions of the introduction hole, the discharge hole, and other portions.
And, at the site of the introduction hole and the discharge hole,
Together directly supported, in other parts, and supported by interposing between the plug and the core and the support body, the plug
The washer, a recess formed on the core side of the washer or
Is a first fitting portion of the convex portion, and a concave portion formed on the support body side.
Or a second fitting portion of a convex portion, wherein the first fitting portion and the second
The two fitting portions are a convex portion or a concave portion formed on the core, and
Fit into each of the convex or concave portions formed on the support,
Since the piston is formed by supporting the core and casting the plug integrally with the piston, the following effects can be obtained.

When casting a piston, a cooling cavity is formed.
Cores at the introduction hole and the discharge hole.
Can be supported by the support at the part where the plug is interposed
Therefore, the core can be held in a stable state. This cooling cavity
Of the inlet and outlet holes of the
Easy to form by supporting with contact support
it can. Then, the plastic interposed between the core and the support
To support the core and the fitting portion of the concave or convex portion of the core.
Fits into the fitting part of the concave or convex part provided on the support
The fitting parts that match each other are provided.
Positioning can be performed accurately, and the core is supported via a plug.
It can be firmly fixed and supported on the holding body. Besides, this
Since the plug has a washer, it is easy to install and cheaper.
Can be interposed between the support and the core in a fixed state.
Workability because it is easy to place on the support.
You. Also, this plug is cast into the piston
Therefore, the core support can be closed with this plug.
Leakage from the cooling cavity to the inside of the skirt
Holes that prevent the formation of holes and allow cooling cavities to communicate with the outside
Can be only the inlet and outlet holes. Therefore,
When the engine is running at high load,
If used at high temperature and high speed
However, cooling oil that has entered the cooling cavity from the insertion hole
There is no leakage to the outside before falling
Therefore, high cooling efficiency can be always maintained. Also,
Since the present invention can be implemented only by casting a plug into the piston, a piston with excellent productivity can be provided.

[Brief description of the drawings]

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

FIG. 2 is a longitudinal sectional view showing an arrangement of a support, a plug and a core set during casting of the piston of FIG. 1;

FIG. 3 is a longitudinal sectional view showing an arrangement state of a support, a plug, and a core set during casting of a piston of an internal combustion engine in Embodiment 2 of the present invention.

FIG. 4 is a longitudinal sectional view showing an arrangement state of a support, a plug and a core set during casting of a piston of an internal combustion engine in Embodiment 3 of the present invention.

FIG. 5 is a longitudinal sectional view showing an arrangement state of a support, a plug and a core set during casting of a piston of an internal combustion engine in Embodiment 4 of the present invention.

FIG. 6 is a bottom view of a piston of an internal combustion engine in a conventional example.

FIG. 7 is a vertical sectional view taken along line AA of FIG. 6;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Piston 2 Ring groove 3 Cooling cavity 4 Skirt part 5 Inlet hole 6 Discharge hole 7 Core support part 11 Core 12 Recess 13 Convex part 21 Support body 22 Recess 23 Convex part 31 Plug 32 First fitting part 33 Second fitting Joint 34 Washer

Claims (1)

(57) [Scope of request for utility model registration] A piston having an annular cooling cavity formed inside a ring groove of a piston, a cooling oil introduction hole communicating with an inside of a skirt portion of the cooling cavity, and a discharge hole. At the time of casting, the core forming the cooling cavity is divided into the introduction hole, the discharge hole, and the like.
Is supported by a support, and the portions of the introduction hole and the discharge hole are supported.
Position, directly supported by the support, and other parts
And a plug interposed between the core and the support to support the plug, the plug comprising a washer and the core of the washer.
A first fitting portion of a concave portion or a convex portion formed on the side,
The body and the second fitting part of the concave or convex part formed on the body side
The first fitting portion and the second fitting portion are formed on the core.
Convex or concave, and convex or concave formed on the support.
A piston for an internal combustion engine , wherein the piston is formed by fitting each of the parts, supporting the core, and casting the plug integrally with the piston.