JP2005201099A - Piston and cylinder for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston and a cylinder for an internal combustion engine, each having a sliding part with a composite plating layer which is formed by uniformly dispersing fluorine resin in metal excellent in wear resistance and self-lubricating property with a one-time surface treatment. <P>SOLUTION: The piston is made from meatal containing aluminum, and has a groove for a piston ring formed in its outer circumferential face. The piston has nickel plating coating of the thickness of 5 to 20 μm formed by dispersing and compounding fine particles of fluorine resin with particle diameter of 0.1 to 0.5 μm on at least a surface brought into contact with the cylinder. The cylinder is made from aluminum alloy or cast iron. The cylinder has nickel plating coating of the thickness of 5 to 20 μm formed by dispersing and compounding fine particles of fluorine resin with particle diameter of 0.1 to 0.5 μm on at least a surface brought into contact with the piston. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a piston and a cylinder used in an internal combustion engine with improved wear resistance of sliding portions.

  In recent years, there has been an increasing demand for weight reduction in internal combustion engines and the like in order to reduce fuel consumption from the viewpoint of energy saving. In order to meet such demands, light metals such as aluminum-containing metals are actively used.

However, aluminum-containing metals are generally required to be improved in terms of heat resistance, rigidity, and mechanical strength. In particular, when used as a sliding member such as a piston or cylinder for an internal combustion engine, there is a problem that durability such as wear resistance is lacking. For the purpose of improving such problems, various surface treatments have been proposed for the surface of an aluminum-containing metal. In the case of a general-purpose internal combustion engine, a combination of a piston made of an aluminum alloy casting and a cylinder made of an aluminum alloy die cast having a sliding surface plated with hard chrome is common. However, this combination has a problem of high manufacturing cost and inferior durability.
JP-A-11-193478 Japanese Utility Model Publication No. 5-66246

In a general internal combustion engine piston / cylinder combination, the piston is made of an aluminum-containing metal and the cylinder is made of an aluminum alloy or cast iron. The piston is iron-plated on the sliding surface with the cylinder to prevent seizure, and the inner surface of the groove for fitting the piston ring is hard anodized to prevent wear due to contact with the piston ring. Applied to form a film.

When manufacturing the said piston, since the iron plating of the sliding surface and the hard anodized film of the groove | channel for piston rings were provided in a separate process, respectively, there existed a problem that a manufacturing process was complicated.

  A coating made of an A1-OH-F compound is coated on a piston made of an aluminum-containing metal for the purpose of improving durability such as wear resistance of the aluminum-containing metal (for example, JP-A-11-193478) (See Japanese Utility Model Laid-Open No. 5-66246) for which the surface of the piston is covered with a fluorine resin composite nickel plating layer. With these composite plating films, a film can be applied to the sliding surface and the piston ring groove at a time. However, in this method, the particle diameter of the fluororesin contained in the composite plating film is as large as 1 to 100 μm, non-uniformity, low adhesion with the aluminum-containing metal, and particles easily fall off during sliding. Moreover, when it falls off, a large unevenness | corrugation generate | occur | produces on the surface and there existed a problem of inhibiting the durability.

The present invention solves the above-mentioned conventional problems. A composite plating layer in which a fluororesin is uniformly dispersed in a metal having excellent wear resistance and self-lubricating property at a sliding portion is treated once. An object of the present invention is to provide a piston and cylinder for an internal combustion engine formed by the above.

The present invention is a piston made of an aluminum-containing metal having a groove for a piston ring on its outer peripheral surface, in which fluororesin fine particles having a particle size of 0.1 to 0.5 μm are dispersed and combined on at least the surface in contact with the cylinder. The film thickness is 5 to 20 μm. Further, the present invention is a cylinder made of an aluminum alloy or cast iron, and has a film thickness of 5 to 20 μm in which fluororesin particles having a particle size of 0.1 to 0.5 μm are dispersed and combined on at least the surface in contact with the piston. It has the structure which consists of a nickel metal plating film.

The present invention realizes a piston and a cylinder for an internal combustion engine in which a composite plating layer in which a fluororesin is uniformly dispersed in a metal having excellent wear resistance and self-lubricating property on a sliding portion is formed by a single surface treatment. It can be done.

The invention described in claim 1 of the present invention is a piston made of an aluminum-containing metal having a groove for a piston ring on its outer peripheral surface, and fluorine having a particle diameter of 0.1 to 0.5 μm on at least the surface in contact with the cylinder It is a configuration for an internal combustion engine piston provided with a nickel metal plating film in which resin fine particles are dispersed and combined. With this configuration, an internal combustion engine piston that realizes excellent self-lubricity can be obtained. .

The invention according to claim 2 is a structure for a piston for an internal combustion engine provided with a plating film thickness of 5 to 20 μm in which fine particles of fluororesin are dispersed and combined, and this structure provides excellent abrasion resistance. It can be set as the piston for internal combustion engines which implement | achieves wear property.

  The invention according to claim 3 is a nickel metal plating film which is a cylinder made of an aluminum alloy or cast iron, in which fine particles of fluororesin having a particle size of 0.1 to 0.5 μm are dispersed and combined on at least the surface in contact with the piston The cylinder for an internal combustion engine is provided, and the cylinder for an internal combustion engine that realizes excellent self-lubricity can be obtained by this configuration.

The invention according to claim 4 is a structure for a cylinder for an internal combustion engine having a plating film thickness of 5 to 20 μm in which fine particles of fluororesin are dispersed and combined, and this structure provides excellent abrasion resistance. It can be set as the cylinder for internal combustion engines which implement | achieves wear property.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view of a piston for an internal combustion engine according to an embodiment of the present invention. In FIG. 1, 1 is a piston, 2 is an aluminum-containing metal base material, 3 is a plating film, 4 is a ring groove, 5 is a skirt portion, and 6 is a pin hole portion. FIG. 2 is a conceptual diagram of a plating film in one embodiment of the present invention. 7 is a fine particle of fluororesin, and 8 is a nickel plating film.

The internal combustion engine piston configured as described above will be described below.

AC8A material (JIS H5202) is cast to form a piston 1 shape for an internal combustion engine having a ring groove 4 and a pin hole portion 6 as shown in FIG. 1, and a skirt portion 5 which is a sliding surface with a cylinder is machined. Nickel with a plating film thickness of 5 to 20 μm, finished with a surface state with a pitch of 0.1 to 0.3 μm and a roughness of 6 μm and dispersed and combined with fluororesin fine particles 7 with a particle size of 0.1 to 0.5 μm on the entire surface. A metal plating film 3 is formed. Conventional fluororesin (Teflon (registered trademark) PTFE: Tetrafluoroethylene resin, DuPont, USA) has a melting point of 327 ° C and a continuous use temperature of 260 ° C. Thus, a heat resistant temperature of 350 ° C. can be realized. The fine particles 7 of the fluororesin are uniformly dispersed and combined in the nickel plating layer 8 as shown in FIG.

For comparison, in the same manner as in Example 1, the piston 1 for an internal combustion engine having a ring groove 4 and a pin hole portion 6 is formed, and the skirt portion 5 which is a sliding surface with the cylinder is machined to a pitch of 0.1. And finished with a surface state of 0.3 μm and roughness of 6 μm, and a nickel metal plating film having a thickness of 20 to 50 μm was formed by dispersing and combining conventional fluororesin fine particles having a particle diameter of 1 to 5 μm over the entire surface. A thing (comparison piston 1) is prepared.

Moreover, the cylinder which becomes the other party of Example 1 and the comparison piston 1 finishes ADC12 material (JISH5302) to a predetermined cylinder block shape by casting. The sliding surface with the piston is machined to a surface with a pitch of 3 μm and roughness of 3 μm (cylinder A), and the machined sliding surface is made of fluororesin with a particle size of 0.1 to 0.5 μm. Prepare a nickel metal plating film (cylinder B) having a thickness of 5 to 20 μm in which fine particles are dispersed and combined. The piston ring is made of gray cast iron.

The actual machine endurance experiment was implemented in the combination shown in Table 1 in a two-cycle air-cooled two-cylinder engine under the conditions of a rotation speed of 5,200 rpm, a full load, and a test time of 100 hours. The results are also shown in Table 1.

As shown in the results of Table 1, the combination of the piston, cylinder A, and cylinder B of Example 1 of the present invention was superior in wear resistance as compared to the combination of comparative piston 1 and cylinder A.

1 is a schematic diagram of a piston for an internal combustion engine in Embodiment 1 of the present invention. Conceptual diagram of plating film in Example 1 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piston 2 Aluminum containing metal base material 3 Plating film 4 Ring groove 5 Skirt part 6 Pin hole part 7 Fine particle of fluororesin 8 Nickel plating film

Claims (4)

  Piston made of aluminum-containing metal having a groove for piston ring on its outer peripheral surface, nickel metal plating in which fine particles of fluororesin having a particle size of 0.1 to 0.5 μm are dispersed and combined on at least the surface in contact with the cylinder A piston for an internal combustion engine, characterized by having a film. 2. The piston for an internal combustion engine according to claim 1, wherein the thickness of the plating film in which fine particles of fluororesin are dispersed and combined is 5 to 20 [mu] m. An internal combustion engine comprising a cylinder made of aluminum alloy or cast iron, and having a nickel metal plating film in which fine particles of a fluororesin having a particle size of 0.1 to 0.5 μm are dispersed and combined on at least a surface in contact with a piston Cylinder. 4. A cylinder for an internal combustion engine according to claim 3, wherein the thickness of the plating film in which fine particles of fluororesin are dispersed and combined is 5 to 20 [mu] m.

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