JPH0583346U - Piston for internal combustion engine - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a piston for an internal combustion engine capable of reliably storing unburned gas without becoming a heat spot. [Structure] A top ring 3 is defined by engraving a top ring groove 2 on an outer peripheral surface of a crown portion 1 which constitutes a piston main body, and a concave groove 4 which is enlarged and opened to the outer peripheral side is formed on the top land 3. In the installed piston for internal combustion engine,
The side portion 4 ₁ on the combustion chamber side of the concave groove 4 is formed to be inclined more than the side portion 4 ₂ on the top ring groove 2 side, while the side portions 4 ₁ and 4 _{2 of the} concave groove 4 and the top land 3 are formed. Convex arc portions 4 ₄ and 4 ₅ were formed on the continuous portion.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

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

[0002]

[Prior Art]

Conventionally, as a piston for an internal combustion engine, for example, there is one described in Japanese Utility Model Laid-Open No. 62-145962. In this piston for an internal combustion engine, as shown in FIG. 3, a top ring 13 is formed by engraving a top ring groove 12 on the outer peripheral surface of a crown portion 11 that constitutes the piston body 10, and this top land 13 is defined. Is provided with at least one recessed groove 14 that is enlarged and opened to the outer peripheral side. Then, the unburned gas flowing between the top land 13 and the cylinder bore 15 during the operation of the engine is depressed into the concave groove 14
The unburned gas is stored inside to prevent the unburned gas from flowing toward the top ring groove 12 as much as possible.

[0003]

[Problems to be solved by the device]

However, in the conventional piston for internal combustion engine, the concave groove 14 is formed in an isosceles trapezoidal cross section, and the side portions 14 ₁ and 14 _{2 of} the concave groove 14 and the top land 13 are connected to each other. The edge portion 16 is formed. For this reason, the edge portion 16 becomes a heat spot during engine operation, and the heat causes the top land 13 and the cylinder bore 1 to be heated.
5, the unburned gas existing in the concave groove 14 spontaneously ignites and knocking occurs. Due to this knocking, there is a defect that the top land 13 is damaged and the edge portion 16 is damaged and the concave groove 14 does not function.

The present invention has been made to solve the above problems, and an object thereof is to provide a piston for an internal combustion engine capable of reliably storing unburned gas without forming a heat spot.

[0005]

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention defines a top land by engraving a top ring groove on the outer peripheral surface of the crown portion of the piston body, and in this top land, a concave groove that expands and opens to the outer peripheral side is formed. In a circumferentially arranged piston for an internal combustion engine, a side portion on the combustion chamber side of the concave groove is formed to be inclined more than a side portion on the top ring groove side, and a side portion of the concave groove and a top land are continuously provided. A convex arc portion is formed on the portion.

[0006]

[Action]

According to the above configuration, since the edge portion that becomes the heat spot is eliminated, the unburned gas flowing between the top land and the cylinder bore does not ignite.

[00
The unburned gas smoothly enters and accumulates along the side of the concave groove on the combustion chamber side, and the amount of unburned gas flowing to the top ring groove side decreases.

Even if knocking occurs, since the side portion of the concave groove on the side of the top ring groove rises with a smaller inclination than the side portion on the side of the combustion chamber, the generated combustion gas causes the top land and the cylinder bore. After entering the groove along the side on the combustion chamber side of the groove from between,
A swirling flow that returns to the combustion chamber side is formed, and it becomes difficult for the combustion gas to flow to the top ring groove side.

[0009]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 (1) is a front view showing a piston for an internal combustion engine, FIG. 1 (2) is an enlarged sectional view showing a top land in the piston of FIG. 1 (1), and FIG.

An annular top ring groove 2 is engraved on the outer peripheral portion of the crown portion 1 that constitutes the piston body, and thereby a top land 3 is defined.

At least one thrust groove 4 (one in the embodiment) that expands to the outer peripheral side is provided around at least the thrust side of the top land 3. The concave groove 4 has a depth of d and an opening width of W ₁ + W ₂ , and is substantially V-shaped.
Formed in ₁ and the top ring groove 2 side portion 4 ₂ Togatotsu arcuate bottom 4 ₃ are formed on the concave arcuate, said side 4 _1, 4 ₂ smoothly through the bottom portion 4 ₃ It is lined up. Further, the side of the combustion chamber side 4 ₁ and the top lands 3 and convex arcuate portion 4 ₄ to connecting portion of
There is formed, convex arcuate portion 4 ₅ The connecting portion of the side 4 ₂ and the top lands 3 of the top ring groove 2 side. Side 4 ₁ of the combustion chamber side is formed to be inclined larger than the sides 4 ₂ of the top ring groove 2 side.

Specifically, the dimensions of each part of the concave groove 4 are set as follows.

The radius of curvature R ₁ of the side portion 4 ₁ on the combustion chamber side is 1.0 or more and 2.5 or less, and the radius of curvature R ₂ of the side portion 4 ₂ on the top ring groove 2 side is 1.5 or more and 3. 0 or less, radius of curvature R ₁ , R ₂
Is a R _{2 <R 1,} convex arcuate portion 4 ₄ is formed with a radius of curvature R ₁ on the side 4 ₁ and concentric combustion chamber side, convex arcuate portion 4 ₅ of the top ring groove 2 side It is formed with a radius of curvature R ₂ the sides 4 ₂ concentrically. Further, the bottom ₄ of curvature radius _{R 3} of ₃ 0.7 or less 0.3 or more, the depth d from the top land 3 deepest site of the bottom _{4 3} has a 1.4 or less 0.7 or more .. Furthermore, the opening width is 2.0 or less 1.0 or more, the bottom _{4 3}
The dimension W ₁ on the combustion chamber side when the opening width is divided into two at the center of curvature is larger than the dimension W ₂ on the top ring groove 2 side plus 0.1.

[0015] Incidentally, in this embodiment, by forming the sides 4 ₁ of the combustion chamber side of the groove 4 in a convex arc shape, this and the top land 3 the convex arcuate portion 4 ₄ identical curvature radii concentrically of one to be formed in the connecting portion, continuously arranged between the top ring to form the sides 4 ₂ grooves 2 side in a convex arc shape, this same curvature concentric radius of convex arcuate portion 4 ₅ Top lands 3 was formed on the part, the side 4 ₁ of the combustion chamber side and the side portion 4 ₂ of the top ring groove 2 side is formed in a linear shape, convex arcuate portion 4 ₄ so as to connect it to the top land _3, 4 ₅ It is needless to say that may be formed in the connecting portion between the top lands 3 and 4 ₁ and 4 ₂ of the concave groove 4.

In the above-described structure, the crown surface 1 of the crown portion 1 as shown in FIG.
Even if unburned gas flows between the top land 3 of the piston body that slides in the cylinder bore 5 due to the combustion gas pressure in a and the cylinder bore 5, the concave groove 4 does not have an edge portion that becomes a heat spot. The unburned gas flowing between the top land 3 and the cylinder bore 5 does not spontaneously ignite.

[0017] The unburned gas reservoir enters smoothly into the concave groove 4 along the sides 4 ₁ of the combustion chamber side of the groove 4, the amount flowing to the top ring groove 2 side is reduced.

In an engine or the like having a high output and a high compression ratio, even if unburned gas that has entered between the top land 3 and the cylinder bore 5 or in the groove 4 spontaneously ignites and knocks, knocking occurs. in generated combustion gas is entering the concave groove 4 along the sides 4 ₁ of the combustion chamber side of the groove 4 between the top land 3 and the cylinder bore 5, the top ring groove 2 side of the groove 4 since side 4 ₂ is up standing inclined less than the side 4 ₁ of the combustion chamber side, or al the flow of the combustion gas as shown by arrow in FIG. 3 the swirling flow back to the combustion chamber side It becomes difficult for the combustion gas to flow to the top ring groove 2 side.

[0019]

[Effect of the device]

As described above, the invention is an internal combustion engine in which a top ring is defined by engraving a top ring groove on the outer peripheral surface of the crown portion of the piston body, and a concave groove that expands to the outer peripheral side is provided around the top land. In the piston for use, the side portion on the combustion chamber side of the concave groove is formed so as to be inclined more than the side portion on the top ring groove side, and a convex arc portion is formed on the connecting portion between the side portion of the concave groove and the top land. Since the edge portion that forms the heat spot is eliminated, it is possible to reliably prevent spontaneous combustion of the unburned gas flowing between the top land and the cylinder bore. Further, the unburned gas flowing between the top land and the cylinder bore is guided by the side portion of the concave groove on the combustion chamber side and stored in the concave groove, and the amount of unburned gas flowing to the top ring groove side can be reduced. .. Further, even if knocking occurs, the combustion gas generated will rise in the top land because the side of the concave groove on the top ring groove side rises with a smaller inclination than the side of the combustion chamber. After entering the groove along the side of the groove on the combustion chamber side from between the cylinder bore and the cylinder bore, a swirling flow that returns to the combustion chamber side is formed, and the combustion gas flows to the top ring groove side. It can be difficult. Therefore, the occurrence of knocking can be prevented, and the concave groove can be sufficiently functioned, thereby eliminating the possibility that the top land is damaged, the top ring is seized, and the top ring groove is worn.

[Brief description of drawings]

FIG. 1 is a front view showing a piston for an internal combustion engine which is an embodiment of the present invention. (2) It is an enlarged sectional view showing a top land in the piston of (1).

FIG. 2 is an explanatory view of the operation of the piston shown in FIG.

FIG. 3 is a cross-sectional view corresponding to FIG. 1 (2) showing a top land in a piston for an internal combustion engine of a conventional example.

[Explanation of symbols]

1 crown part 2 top ring groove 3 top land 4 concave groove 4 ₁ side part on combustion chamber side 4 ₂ side part on top ring groove side 4 ₃ bottom part 4 ₄ 4 ₅ convex arc-shaped part

Claims (1)

[Scope of utility model registration request] 1. A piston for an internal combustion engine in which a top ring is formed by engraving a top ring groove on an outer peripheral surface of a crown portion of a piston main body, and a concave groove that is enlarged and opened to the outer peripheral side is formed around the top land. In, the combustion chamber side side portion of the concave groove is formed so as to be inclined more than the top ring groove side side portion, and a convex arc portion is formed in the connecting portion between the concave groove side portion and the top land. A piston for an internal combustion engine characterized by the above.