JP2005201101A - 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 coating layer excellent in wear resistance and self-lubricating property. <P>SOLUTION: The cylinder is made from aluminum alloy or cast iron. At least a surface brought into contact with the piston has a coating layer of the thickness of 20 to 50 μm formed by dispersing and compounding fine particles of fluorine resin with particle diameter of 0.1 to 1 μm and fine particles of ceramics with particle diameter of 0.1 to 1 μm. The piston is made from meatal containing aluminum and has a groove for a piston ring formed in its outer circumferential face. At least a surface brought into contact with the cylinder has a coating layer of the thickness of 20 to 50 μm formed by dispersing and compounding the fine particles of fluorine resin with particle diameter of 0.1 to 1 μm and the fine particles of ceramics with particle diameter of 0.1 to 1 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

  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, it has been proposed to perform various surface treatments on the surface of the 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, the hard chrome electroplating process applied to the cylinder has a problem that the plating current efficiency is as low as about 20%, the film forming speed is remarkably slow, and the cost is high. In addition, the hard chrome plating process has problems such as being subjected to strong regulations for environmental protection in the treatment of chrome plating waste liquid and the like.

  In place of this hard chrome plating, a method using nickel plating has been proposed, but nickel is considered a carcinogenic substance, and its use is currently prohibited in decorative items such as necklaces and earrings that directly touch the human body. Yes.

  In the near future, there will be a problem that nickel will be subject to regulation in internal combustion engine members such as cylinders and pistons, and if necessary, it will need to be abolished.

  The present invention solves the above-described conventional problems, and an object thereof is to provide a cylinder and a piston for an internal combustion engine in which a coating layer having excellent wear resistance and self-lubricating properties is formed on a sliding portion.

  The present invention relates to a cylinder made of an aluminum alloy or cast iron, and at least the surface of the aluminum alloy or cast iron in contact with the piston has a fine particle of fluororesin having a particle size of 0.1 to 1 μm and a ceramic having a particle size of 0.1 to 1 μm And a coating layer having a thickness of 20 to 50 μm in which the fine particles are dispersed and combined.

  Further, 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 a fluororesin fine particle having a particle size of 0.1 to 1 μm and a particle size of 0. It has a configuration comprising a coating layer having a thickness of 20 to 50 μm, in which ceramic fine particles of 1 to 1 μm are dispersed and combined.

  As an effect of the present invention, a slide having a coating layer having a thickness of 20 to 50 μm formed by dispersing and combining fluororesin fine particles having a particle size of 0.1 to 1 μm and ceramic fine particles having a particle size of 0.1 to 1 μm on the surface. It is possible to realize a cylinder and a piston for an internal combustion engine that has excellent wear resistance and self-lubricating properties in a moving part and has a low environmental load.

  The invention described in claim 1 of the present invention is a cylinder made of an aluminum alloy or cast iron, and at least the surface of the aluminum alloy or cast iron in contact with the piston has fine particles and particles of fluororesin having a particle diameter of 0.1 to 1 μm. This is a structure for an internal combustion engine cylinder having a coating layer in which ceramic fine particles having a diameter of 0.1 to 1 μm are dispersed and combined, and this structure provides excellent self-lubrication and wear resistance. It can be set as the cylinder for internal combustion engines implement | achieved.

The invention according to claim 2 is a configuration for a cylinder for an internal combustion engine provided with a coating layer of 20 to 50 μm in which fine particles of fluororesin and ceramic fine particles are dispersed and combined, and by this configuration, It can be set as the cylinder for internal combustion engines which implement | achieves the outstanding abrasion resistance.

The invention according to claim 3 is a piston made of an aluminum-containing metal having a groove for a piston ring on its outer peripheral surface, and at least a surface in contact with the cylinder is made of fluororesin fine particles and particles having a particle size of 0.1 to 1 μm This is a configuration for a piston for an internal combustion engine provided with a coating layer in which ceramic fine particles having a diameter of 0.1 to 1 μm are dispersed and combined, and this configuration provides excellent self-lubrication and wear resistance. The internal combustion engine piston can be realized.

The invention according to claim 4 is a structure for a piston for an internal combustion engine provided with a coating layer in which fine particles of fluororesin and fine particles of ceramic 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.

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

  FIG. 1 is a conceptual diagram of a coating layer in Example 1 of the present invention. In FIG. 1, 1 is a metal base material of a cylinder and a piston, 2 is a fine particle of fluororesin, 3 is a fine particle of ceramic, 4 is an underlayer, 5 is an intermediate layer, and 6 is a surface layer.

The cylinder for an internal combustion engine thus configured will be described below.

A cylinder finishes ADC12 material (JISH5302) to a predetermined cylinder block shape by casting. The sliding surface with the piston is finished to a surface state with a pitch of 3 μm and a roughness of 3 μm by machining, and as shown in FIG. 1, the machined sliding surface has a large number of ceramic fine particles 3 having a particle diameter of 0.1 μm to 1 μm. Inclined plating is performed with a strong underlayer 4, an intermediate layer 5 that relieves abrupt changes in the structure, a surface layer 6 with a fine particle 2 of fluororesin having a particle diameter of 0.1 to 1 μm. Thereby, lubricity can be realized in the surface layer 6, and abrasion resistance can be realized in the intermediate layer 5 and the underlayer 4. The fluororesin fine particle 2 is a conventional fluororesin PTFE (tetrafluoroethylene resin, US DuPont) having a melting point of 327 ° C. and a continuous use temperature of 260 ° C., and the fluororesin PFA (perfluoroalkoxy resin, US DuPont) is The melting point is 300 ° C. to 310 ° C., and the continuous use temperature is 260 ° C., but the heat resistance temperature of 350 ° C. can be realized by repeating dissolution and cooling and solidification a plurality of times to form fine particles.

In the first embodiment, the piston for the internal combustion engine is finished to a surface state with a pitch of 0.1 to 0.3 μm and a roughness of 6 μm by machining the skirt portion which is a sliding surface with the cylinder. Further, the machined sliding surface has a strong base layer 4 with a large amount of ceramic fine particles 3 having a particle size of 0.1 to 1 μm, an intermediate layer 5 that alleviates a sudden change in structure, and a particle size of 0.1 to 1 μm. A surface layer 6 having a large amount of fine particles 2 of fluororesin and inclined plating are applied. As a result, the surface layer 6 can achieve lubricity, the intermediate layer 5 and the underlayer 4 can achieve wear resistance, dissolution, and cooling and solidification a plurality of times, and high heat resistance of 350 ° C. can be realized with finely divided fluororesin. is there. The piston ring is made of gray cast iron.

  As a comparative example, a conventional cylinder (cylinder A) made of aluminum alloy die-casting with a hard chrome plating on the piston and sliding surface, and the skirt portion that becomes the sliding surface of the cylinder are machined to a pitch of 0.1 to 0 A piston (piston A) finished to a surface state of 3 μm and a roughness of 6 μm was prepared.

The actual machine durability test was incorporated into a two-cycle air-cooled two-cylinder engine in the combinations shown in Table 1, and was carried out under conditions of a rotation speed of 5, 200 rpm, 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 cylinder and piston of Example 1 of the present invention and the conventional cylinder (cylinder A) and piston (piston A) had equivalent performance in terms of wear resistance.

Conceptual diagram of the coating layer in Example 1 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal base material of cylinder and piston 2 Fine particle of fluororesin 3 Fine particle of ceramic 4 Underlayer 5 Intermediate layer 6 Surface layer

Claims (4)

  A cylinder made of an aluminum alloy or cast iron, wherein at least a surface of the aluminum alloy or cast iron in contact with the piston has fluororesin fine particles having a particle size of 0.1 to 1 μm and ceramic fine particles having a particle size of 0.1 to 1 μm. A cylinder for an internal combustion engine having a coating layer dispersed and combined.   2. A cylinder for an internal combustion engine according to claim 1, wherein the coating layer in which the fine particles of fluororesin and the fine particles of ceramic are dispersed and combined has a thickness of 20 to 50 [mu] m.   A piston made of an aluminum-containing metal having a groove for a piston ring on its outer peripheral surface, and at least a surface in contact with the cylinder is made of a fluororesin fine particle having a particle size of 0.1 to 1 μm and a ceramic having a particle size of 0.1 to 1 μm. A piston for an internal combustion engine having a coating layer in which fine particles are dispersed and combined. 4. The piston for an internal combustion engine according to claim 3, wherein the coating layer in which the fine particles of fluororesin and the fine particles of ceramic are dispersed and combined has a thickness of 20 to 50 [mu] m.

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