JPS60245789A - Piston crown of internal-combustion engine - Google Patents

Abstract

PURPOSE:To provide the titled piston crown having excellent resistance to wear and corrosion of piston ring grooves by constituting the groove side face parts of the ring grooves of an alloy material which has hardness higher than the hardness of the piston crown and is nobler than piston rings. CONSTITUTION:The top and bottom surfaces of the groove side face of, for example, the 1st ring groove 11 formed to the piston crown 1 are constituted of the alloy material 3 which is harder than the crown 1 and nobler than the ring. An Ni or Co alloy is adequate for the material 3 if the crown 1 and the ring are made of an ordinary material. The groove side face part of the groove 11 is made into an approximately trapezoidal sectional shape and a welding material 14 is embedded therein by welding and is then machined and polished to a prescribed shape in the case of providing the material 3 by welding to the crown 1. An annular alloy material 5 is brazed to the groove side face of the groove 11 and is machined or polished in the case of brazing. The material 3 is provided to one or both of the top and bottom surfaces on the groove side faces of at least >=1 grooves among the grooves 11, 12, 13. The effect is better if said material is provided on the bottom surface in the groove side face part of the groove 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a piston crown for an internal combustion engine, and more particularly to a piston crown for an internal combustion engine in which the corrosion resistance and wear resistance of a ring groove are improved.

[Background of the Invention] Fig. 1 is a sectional view showing the general structure of a piston crown, in which a plurality of ring grooves 2 are provided in a circumferential manner on the side circumferential surface of the piston crown l. A piston ring such as a pressure ring for making the space between the ring groove 2 and the inner wall of the cylinder airtight, and an oil ring for distributing and scraping lubricating oil uniformly over the inner wall of the cylinder is attached.

Among these ring grooves, the ring groove located on the combustion chamber side, especially the first ring groove (hereinafter sometimes referred to as the first ring groove, second ring groove, fist, etc. in the order of proximity to the combustion chamber). Extremely high combustion gas pressure is applied to the groove side surfaces, and they are exposed to corrosive combustion gases, so they are susceptible to wear and corrosion.

Conventionally, measures to improve the wear resistance of ring grooves include
Hardness has been increased by applying chrome plating to the ring groove, or by heat treatment such as induction hardening or flame hardening, but as the output of internal combustion engines increases and the quality of fuel deteriorates, even better hardness is achieved. Measures for wear resistance and corrosion resistance are desired.

[Object of the Invention] An object of the present invention is to solve the problems of the prior art described above and to provide a piston crown for an internal combustion engine in which the corrosion resistance and wear resistance of the ring groove are significantly improved.

[Structure of the Invention] In order to achieve this object, the piston crown of the internal combustion engine of the present invention includes a groove side surface of the piston ring groove made of an alloy material that is harder than the piston crown and harder than the piston ring. Along with configuring.

This alloy material is joined to the piston crown by welding or brazing.

In the present invention, such an alloy material may be provided in all the ring grooves, or may be provided in some parts, for example, only in the first ring groove or only in the first ring groove and the second ring groove.

Further, this alloy material may be provided on one of the upper surface and the f-plane of the groove side of the ring groove, or may be provided on both.

In internal combustion engines with large cylinder diameters, the piston crown is usually made of cast steel, RX steel, cast forged steel, etc., and in small-diameter internal combustion engines, the piston crown is mainly made of aluminum alloy. Also, cast iron, cast steel, etc. are used as the material for the piston ring. In the case of such ordinary materials, the alloy material of the present invention is a nickel-based alloy.

Cobalt-based alloys and the like are preferred.

Chrome plating or molybdenum coating may be applied to the side surface of the piston ring, but in this case, the material of the alloy material of the present invention is selected so that it is more durable than chromium or molybdenum.

[Embodiments of the invention] Examples will be described below with reference to the drawings.

FIG. 2 is a longitudinal cross-sectional view of the piston crown according to the embodiment of the present invention, in which the upper and lower surfaces of the groove side surfaces of the first ring groove 11 are made of a harder alloy material than the piston crown, and are harder than the piston crown. It is composed of 3.

FIG. 3 is a diagram illustrating an example of a method for welding the alloy material 3 to the piston crown l. In FIG. 3, first, the groove side portion of the ring groove 11 is cut to provide a welding groove so that the groove 2 has a substantially trapezoidal cross-sectional shape. Next, welding material 4 (indicated by a two-dot chain hatch in the figure) is welded and filled into the link groove 11. After welding is completed, the welding material 4 is cut and polished to form a ring groove of a predetermined size, thereby obtaining a piston crown having the structure of the present invention.

FIG. 4 is a diagram illustrating a method of providing an alloy material by brazing. First, a ring-shaped alloy material 5 is brazed to the groove side surface of the ring groove 11. Then, by cutting or polishing, a piston crown having the structure of the present invention is obtained.

In addition, although the alloy material is provided in the first ring groove 11 in the embodiment mentioned above, the alloy material may be provided in the groove side surfaces of the other ring grooves, for example, all of the ring grooves 11 to 13. The alloy material may be provided only on any one or two groove side surfaces among the grooves 1 to 13. Since the first ring groove 11 is subjected to the greatest pressure and is exposed to the highest temperature combustion gas, it is effective to provide an alloy material on the side surfaces of the first ring groove 11, especially on the F side. be.

In the piston crown configured in this manner, the side surface of the ring groove has high hardness, so it has excellent wear resistance. Furthermore, since the material of the side surface of the ring groove is stronger than that of the piston ring, the corrosion rate of the ring groove is lower than that of the piston ring, and the corrosion resistance of the ring groove is extremely high. Therefore, even if corrosive wear progresses, only the piston ring needs to be replaced, making repairs extremely simple and quick.

[Effects of the Invention] As detailed above, in the piston crown of the internal combustion engine of the present invention, the groove side surface of the ring groove is made of an alloy material that is harder than the piston crown and harder than the piston ring. Excellent wear resistance and corrosion resistance of the ring groove.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a conventional piston crown, FIG. 2 is a longitudinal sectional view of a piston crown according to an embodiment of the present invention, and FIGS.
Each figure is an enlarged view of the main part of FIG. 2. 1-φ・Piston crown, 2.11~13@...Piston ring groove 3.5...Alloy material, 4...Welding material. Agent Patent Attorney Tsuyoshi Shigeno Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] (1) In a piston crown for an internal combustion engine having a plurality of piston ring grooves on the side circumferential surface, one or both of the upper and lower groove side surfaces of at least one piston ring groove is higher than the piston crown. A piston crown for an internal combustion engine, characterized in that the piston crown is made of an alloy material which is harder than a piston ring, and the alloy material is welded or brazed to the piston crown.