JPS62225753A - Piston for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent an oscillating phenomenon, scarf abrasion and the like, by forming a crown section and a skirt section, independently from each other, then by coupling them with the use of a rib through the intermediary of a pin boss section so that they are formed in one unit body, and by reducing the wall thickness of an apex section extending from the crown section to at least a first piston ring. CONSTITUTION:A crown section 1 and a skirt sections 2 are coupled with each other through a pin boss section 4 integrally incorporated with the skirt section 4 and a rib 5. Accordingly, the quantity of heat transmitted from the crown section 1 to the skirt section 2 is also reduced so that the gap between the skirt section 2 and the associated cylinder bore may be made smaller, and therefore, the attitude of a piston is stabilized, resulting in that it is possible to reduce slap and noise. Further, a gouge 9 is formed in the upper section of inner peripheral surface of the crown section 1 or slits are formed in the apex section over the entire circumference thereof. Thus, it is possible to restrain the transmission of heat from the crown section so that the temperature of the piston ring groove may be lowered, thereby it is possible to enhance the wear-resistance of a piston ring and the piston groove section.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a piston for an internal combustion engine suitable for application to an internal combustion engine for an automobile, particularly a diesel internal combustion engine.

(Prior art) Pistons for internal combustion engines are generally disclosed in Japanese Patent Application Laid-Open No. 54-67822.
As shown in the publication, it has an integral structure in which the crown part and the skirt part are connected, and most of the heat that enters the top surface of the crown from the combustion gas is transmitted from the piston ring to the cylinder bore through the thick part of the crown. The rest is transmitted from the thick part of the crown to the cylinder pore via the skirt part. Normally, a gap is provided between the piston and the cylinder bore so that the piston can move smoothly, but due to the expansion caused by the heat, the gap was left larger than the optimum gap.

Therefore, with conventional pistons, when the piston is cold, the gap between the piston and the bore is large, which causes a oscillation phenomenon (slap), which not only causes noise problems, but also causes localized contact with the piston, causing scuff wear and seizure. There was a risk that this would lead to In addition, the heat passing through the piston ring increases the temperature, particularly in the first piston ring groove, resulting in problems such as wear and transfer of piston material to the ring.

(Problems to be Solved by the Invention) The present invention attempts to solve problems such as oscillation phenomenon (slap), scuff wear, and seizure in conventional pistons.

[Structure of the invention]

(Means for Solving the Problems) Therefore, in the piston for an internal combustion engine, the present invention separates the crown part and the skirt part and connects them with a rib through the bottle post part to integrate them, and at least the first It is made by thinning the apex portion leading to the screw knoll groove, and this is used as a means to solve the problem.

(for production) In the configuration of the present invention, the heat that enters the top surface of the crown.

Since the apex corner of the crown is thin, the pressure is transmitted to the first ring of the crown, which prevents problems such as wear due to the temperature drop in the piston ring groove and transfer of piston material to the piston ring. Heat is transferred to the skirt via the pin boss, which is essentially insulated from the crown, and the temperature of the skirt is almost the same as that of the cylinder bore, so the amount of thermal expansion and deformation is small, and the gap between the piston and cylinder bore can be made smaller than necessary. Since there is no need to remove it thickly (there is no need to remove it, there is no oscillation phenomenon).

(Embodiments) The present invention will be described below with reference to embodiments of the drawings. FIGS. 1 and 2 show a first embodiment of the present invention, and FIG. 3 shows a second embodiment of the present invention. First, in the pistons for internal combustion engines (diesel engine) shown in Figures 1 and 2, ■ is the crown part, 2 is the
is a skirt part, both parts 1.2 are separated and a gap 3 is provided, and the crown part 1 and the skirt part 2 are integrally connected via a pin boss part 4 and a rib 5, which are integral with the skirt part 2. ing. Further, the top corner portion 8 extending from the crown top portion 6 to the first piston ring groove 7 is thinned by hollowing out 9 the upper portion of the inner circumferential surface of the crown portion 1 to the upper side portion. Pistons with the above structure are made of high-temperature materials such as cast iron and stainless steel.
It is manufactured from a high-strength material, and even aluminum can be used if the crown is insulated with ceramic coating or the like.

Note that even if the cast iron or stainless steel is used, the gap 3 is provided and the apex portion 8 has a thinner wall structure, so it is not a conventional aluminium. The weight is almost the same as the piston made by Mum, so there is no problem (
Also, even if the wall is made thinner, there is no problem in terms of strength when it is made of cast iron or stainless steel. Furthermore, cast iron and stainless steel materials have a small coefficient of thermal expansion, so even if the temperature of the top surface of the crown rises, the amount of thermal expansion of the entire crown can be reduced, and the piston/
Clearance can be reduced. If the crown is made of aluminum, the same effect as described above can be obtained by attaching a heat insulating material such as ceramics to the top surface of the crown by casting, thermal spraying, or bolting.

FIG. 3 shows a second embodiment, in which a gouge 9 is not provided in the upper part of the inner peripheral surface of the crown part 1 as shown in FIG. By providing a slot 7) 10 over the entire circumference of the apex portion 8a, the apex portion from the crown apex 6 to the first piston/ring groove 7 is made thinner. There is no difference in example and effect.

〔Effect of the invention〕

As explained in detail above, in the present invention, since the apex corner from the crown top to at least the first bisring ring groove is thinned, the amount of heat transmitted from the crown top to the first ring is small (as a result, the ring h% e and the crown This lowers the temperature around the outer periphery of the ring, improving the durability of the ring groove and reducing thermal expansion. This reduces the gap between the piston and cylinder bore, improves the contact between the ring and cylinder bore, and improves the seal. Improves functionality and reduces lubricating oil consumption.

In addition, the crown and skirt sections are separated and integrated by connecting them with ribs via pin boss sections, which reduces the amount of heat transferred from the crown top to the skirt section, thereby reducing the gap between the skirt section and the cylinder bore. , it is possible to stabilize the posture of the piston and reduce slap and noise.

As described above, since the temperature of the ring groove can be lowered, the wear resistance of the ring and the groove can be improved.
Furthermore, by raising the position of the ring groove (reducing the width of the first land), wasted space can be reduced, especially in a diesel engine, thereby improving air utilization and improving performance. In diesel engines, insulating the piston raises the temperature of the combustion chamber, greatly improving combustion at low speeds and under light loads, and improving thermal efficiency.

[Brief explanation of drawings]

FIG. 1 is a front sectional view of a piston showing an embodiment of the present invention;
FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1, and FIG. 3 is a side cross-sectional view showing a part of the top of a piston showing another embodiment. Explanation of the main parts of the diagram: 1...Crown part 2...Skirt part 3...
・Gap 4... Pin post part 5... Rib 6... Crown top 7... First piston ring groove 8... Vertex corner part Fig. 1 Fig. 2

Claims (1)

[Claims] A piston for an internal combustion engine, characterized in that the crown part and the skirt part are separated and integrated by connecting them with a rib through a pin boss part, and the top corner part extending from the top of the crown to at least the first piston ring groove is thinned. Pistons for internal combustion engines.