JP2549516B2 - Internal combustion engine piston and method of manufacturing the same - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to preventing friction between a sliding surface of a piston that slides on a cylinder surface during operation of an internal combustion engine and a contact surface of a piston groove and a piston ring. The present invention relates to a surface treatment, a piston subjected to such treatment, and a method for manufacturing the piston.

[Conventional technology]

Conventionally, pistons for internal combustion engines were mainly produced by molding iron-based casting materials, but with the recent increase in the rotational speed of internal combustion engines, weight reduction is required, and pistons made of aluminum-based alloy materials The outer peripheral surface (including the ring groove) is plated with, for example, nickel, hard chromium, iron, etc. to compensate for the low hardness, which is the drawback of aluminum alloys, for the piston that slides on the cylinder surface at high speed for a long time. The wear resistance of the sliding surface has been improved.

[Problems to be solved by the invention]

It is well known that the conventional method of treating the sliding surface of a member made of aluminum or an aluminum-based alloy as described above is a method of hardening the sliding surface by plating the outer peripheral surface of the piston with nickel or the like. Since the adhesion of the plating layer to the base material in the case of aluminum-based plating is poor, the base material treatment on the base material before the plating process is expensive, and even if this base material treatment is performed, the piston In the case of a member that operates under severe conditions under high temperature as described above, the plating layer may peel off from the aluminum-based substrate due to thermal expansion during operation.

[Means for solving problems]

A piston of an internal combustion engine according to the present invention is formed of an aluminum-based alloy having a high content of silicon, an upper peripheral surface including at least a top ring groove of the piston is anodized, and the fine holes generated by the anodization are formed. The purpose is to fill a lubricating substance composed of a metal sulfide formed by secondary electrolysis in an aqueous solution of a metal thioate.

The high-silicon aluminum used here is JIS aluminum alloy cast AC8B (Si: 8.5 to 10.5),
AC8C (Si: 8.5 to 10.5), AC4A (Si: 8.0 to 10.0), AC4C (S
i: 6.5-7.5) applied is a high silicon aluminum alloy.

[Embodiment 1] FIG. 1 and FIG. 2 are sectional views showing an overall configuration of a cylinder portion in a normal internal combustion engine for explaining an embodiment of the present invention.

In the figure, 1 is a cylinder, 2 is a combustion chamber, 3 is a piston formed of an aluminum alloy that slides on an inner wall and an outer peripheral portion of the cylinder 1 in response to operations such as suction and explosion in the combustion chamber 2, 4 is a piston skirt, 5 is a piston crown, 6 is a top piston ring groove, 7 is a second piston ring groove, 8 is a third piston ring groove, 9 to 11 are piston rings fitted in the ring groove, and 12 is a connecting rod. , 13 are crankshafts.

In the cylinder of the internal combustion engine having the above-described structure, the piston 3 has a JIS aluminum alloy cast AC8B (Si: 8.5 to 1).
0.5), AC8C (Si: 8.5 ~ 10.5), AC4A (Si: 8.0 ~ 10.0), AC
A high silicon aluminum alloy selected from 4C (Si: 6.5-7.5) is applied. By processing the piston 3 into a predetermined shape by turning, grinding, etc., and performing alumite treatment using this as an anode, an alumite layer 14 is formed on the surface of the piston 3 as shown in FIG. 3, and this alumite layer is also formed. Along with the generation of 14, the micropores (PORE) shown by 15 in the figure are generated.

Then, by using the piston 3 after the alumite treatment as an anode, secondary electrolysis is performed in an aqueous solution of a metal thioate salt such as ammonium tetrathiomolybdate, thereby producing fine particles 15 in the fine holes 15. The metal sulfide crystals such as molybdenum disulfide are precipitated and filled.
In this case, molybdenum disulfide filled in the fine holes 15
As described above, since the piston 3 is made of an aluminum-based alloy with a high silicon content as described above, 16 has a high bonding ability to the precipitated crystals due to the action of silicon during the secondary electrolysis, and therefore is filled with a strong fixing force. Become.

The piston 3 processed and treated as described above slides on the inner peripheral surface of the cylinder 1 in FIG. 1 at high speed and for a long time under high temperature (about 400 ° C.) in the cylinder of a normal internal combustion engine. Even with this, molybdenum disulfide 16 which is a solid lubricant and the excellent lubrication performance by the cooperation action of the engine oil cause the occurrence of biting, scoring, galling, etc. on these sliding surfaces. There is no fear of peeling, and an internal combustion engine that can withstand long-term use can be obtained.

Example 2 The present invention will be described with reference to FIG.

In this example, a hard alumite layer 14 is formed on the top ring groove 6 of the piston 3 made of a high silicon content aluminum alloy and the outer peripheral surface 18 including the top ring groove 6, and metal sulfides (not shown) formed by secondary electrolysis in the fine holes. However, such a treatment reduces the problem of friction due to the piston ring groove, particularly the top ring groove 6 and the piston ring 9, and causes considerable wear even if the entire piston is not lubricated. Was confirmed to improve. This is
In this type of piston, it is considered that the piston ring groove, especially the top ring groove, received a load due to the vertical movement of the piston, and if the alumite layer is not formed at least in these parts, the effect will occur. It can be said that it is difficult. It goes without saying that it will be more effective if everything is processed.

〔The invention's effect〕

As described above, according to the present invention, after the piston in the internal combustion engine is processed into a predetermined shape, the upper outer peripheral surface including at least the top piston ring groove is subjected to an alumite treatment, and further the alumite layer is subjected to the secondary electrolysis to form a lubricating substance. Since the internal combustion engine is filled with the fuel, it is possible to obtain an internal combustion engine that can be used for a long time and has excellent startability.

[Brief description of drawings]

1 and 2 are sectional views showing the overall structure of a cylinder portion in a normal internal combustion engine for explaining an embodiment of the present invention, and FIG. 3 shows a secondary electrolysis according to an embodiment of the present invention. FIG. 4 shows a cross-sectional view of a main portion of molybdenum sulfide fixed to a piston, and FIG. 4 shows still another embodiment of the present invention. An alumite layer and a metal sulfide by secondary electrolysis are formed on the outer peripheral portion of the piston including the top ring groove. It is a principal part schematic cross section at the time of forming a layer (not explicitly shown). In the figure, 1 is a cylinder, 3 is a piston, 14 is an alumite layer, 15 is a fine hole, and 16 is molybdenum disulfide. The same reference numerals in the drawings indicate the same or corresponding parts.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C25D 11/20 303 C25D 11/20 303 F02F 3/00 F02F 3/00 R F16J 1/01 F16J 1 / 01 // C10M 103/04 C10M 103/04 (C10M 103/04 125: 26 147: 02) C10N 10:06 10:12 40:00 50:08 70:00 (72) Inventor Koichi Saruwatari Koto, Tokyo 1-5-1, Kiba, Fujikura Electric Cable Co., Ltd. (72) Inventor Reiji Saito 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Cable Co., Ltd. (72) Inventor Rokuro Ito 3226-Toyomachi, Hamamatsu 1 Miyaki Co., Ltd. (72) Inventor Kenichiro Ito 3226-1, Toyomachi, Hamamatsu City Miyake Co., Ltd. (72) Yoshio Koike 3226-1, Toyomachi, Hamamatsu City Miyake Co., Ltd. (56) Reference JP 54 −62 414 (JP, A) Actual development 56-13235 (JP, U) JP 56-4155 (JP, B2) JP 56-47276 (JP, B2) JP 56-53638 (JP, B2) JP 57-15679 (JP, B2) JP 47-15522 (JP, Y1) JP 60-25999 (JP, Y2) "Handbook of Metal Surface Technology", Nikkan Kogyo Shimbun, Sho 45-2- 28, pp. 656-662

Claims (2)

(57) [Claims] [Claim 1] JIS aluminum alloy casting AC4A, AC4C, AC8
B, AC8C upper outer peripheral surface including at least the top ring groove of the piston of the internal combustion engine formed of a high silicon-containing aluminum-based alloy is anodized, and in the fine holes generated by this anodizing treatment, A piston for an internal combustion engine, which is filled with a metal sulfide by a secondary electrolysis treatment in an aqueous solution of a metal thioate. [Claim 2] AC4A, AC4C, AC8 of JIS aluminum alloy casting
Only the upper outer peripheral surface of at least the top ring groove of the piston of the internal combustion engine formed of a high silicon content aluminum-based alloy selected from B and AC8C is anodized to form fine holes on the surface, and then metal thioacid A method for manufacturing a piston for an internal combustion engine, comprising filling the fine pores with a metal sulfide by a secondary electrolysis treatment in an aqueous salt solution.