JPS59121256A - Piston of internal-combustion engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a piston for an internal combustion engine, particularly in a piston pin hole portion.

A piston of an internal combustion engine is connected to a stove via a piston pin, and the piston is configured to be able to swing relative to the connecting rod between the piston, the piston, and the connecting rod.

The piston pin connects all the small ends of the cylinder and connecting rod, and supports the connecting rod so that it can rotate around the piston pin.In two-stroke engines, the piston pin is lubricated by oil in the intake air mixture. The oil is used for lubrication. In this way, the entire amount of oil for lubricating the piston pin should be fully absorbed.Insert a bearing between the small end of the connecting rod, the piston, and the pin to reduce friction, and loosely fit the piston into the piston pin. The vibration of the connecting rod is transmitted to the piston while minimizing the occurrence of friction.

In the above configuration, the pin hole that supports the piston pin of the piston is likely to wear because it rotates under high pressure due to the high surface pressure caused by the explosive load and the swinging of the connecting rod.

And as a measure to prevent wear of the piston pin hole,
One possibility is to increase the pin diameter to completely reduce the surface pressure, but this increases the weight of the bottle due to the increased pin diameter, which increases the weight of the reciprocating part. It is preferable to make it small, that is, thin.

The present invention was made in view of the current state of wear between the piston pin and the pin hole, and was made to improve this.The purpose and purpose of the present invention is to suppress and reduce the wear of the piston pin hole as much as possible, To achieve the above object, the present invention provides a piston for an internal combustion engine that can improve its lifespan and durability.The present invention provides an aluminum anodizing treatment or a chromium treatment on the surface of the pin hole into which the piston pin is slidably fitted. It is characterized by forming a porous film by reverse electroplating the inner surface of the pin hole of a hard metal such as 5.

Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The figure shows a cylinder section of an internal combustion engine, and the embodiment shows a two-stroke engine.

The cylinder section 1 consists of a cylinder block 2 and a cylinder head 3 mounted on the cylinder block 2.
and cylinder block 2 with stud bolt 4 and nut 5
, and 6 in the figure is a positioning pin between the cylinder block 2 and the cylinder head 3. The embodiment shows a water-cooled engine, which is equipped with a water passage 20L 301, and between the mating surfaces 202 and 302 is an O-ring 7 for preventing combustion gas leakage on the inner diameter side, and an O-ring for preventing water leakage on the outer diameter side. 8
are interposed respectively, and the inner diameter cylinder hole 20 of the cylinder block 2 is
A hemispherical concave combustion chamber ceiling portion 303 is formed at the center of the lower surface of the cylinder head 3 above the cylinder head 3 . Above ceiling part 3
An ignition plug 9 is disposed in the center of the cylinder head 3 and is removably screwed onto the center of the cylinder head 3.

The piston 10 is slidable in the cylinder hole 2θ3 [fits], forming a combustion chamber between the ceiling 101 of the piston 10 and the cylinder head ceiling 303, and forming a combustion chamber between the ceiling 101 of the piston 10 and the surrounding skirt. There is a space 1[
13 is formed. The piston 10 is connected to a crankshaft 11 via a connecting rod 12, and a large end 121 at the lower end of the connecting rod 12 connects to the crankshaft 11.
On the other hand, the connecting rod 12 is rotatably connected to the pin 13 on the piston side via a bearing 14 at a small portion 122 at the upper end of the connecting rod 12 . Reference numeral 123 is an oil inlet to the needle bearing provided at the small end of the connecting rod.

Pin holes 104, 104'f are provided across the axially intermediate portion of the skirt portion 102 of the piston 10, and the bottle holes are provided concentrically and spaced apart to the left and right because there is a chamber 103 in the inner diameter portion of the skirt portion. Pit 130 both ends 131, 131
are fitted into the pin holes 104, 104, and the intermediate portion 132 is connected to the small end portion 122 of the Nikon rod. Pit 130 both ends 1
31.131 is rotatably fitted into the pin hole 104.104K, and both axial edges i33.133 of the pin 13 are fitted into the pin hole 104.104. [14 Annular groove 10 provided near the outer end of the inner diameter portion
5.105K The axial direction is fully restricted by the engaging clip 15.

The piston 10 below is made of an aluminum alloy, and the cylinder block and cylinder head are also made of an aluminum alloy.The inner peripheral surface of the cylinder hole is, for example, chromium plated, and the piston piston is made of, for example, nickel chromium molybdenum steel. is formed.

In the above process, the inner peripheral surface of the piston pin hole 104 is made porous with a hard treated coating.

First, as an example, aluminum is anodized to form a porous film on the inner peripheral surface of the bottle hole 104.

The method begins with a piston made of aluminum alloy.
．． 0, the bottle hole is sealed except for the inner peripheral surface of the pin hole 104 and covered with a removable masking material, and then the pin hole 104 is sealed.
The piston 10 is opened, the piston 10 is connected to the anode, and the electrolytic bath is put into the electrolytic bath to perform anodizing treatment. Through this treatment, as shown in FIG. 2, an oxide film having holes a is formed on the surface of the pin hole, and a permeable layer C, which is the base of the oxide film, penetrates into the inner surface of the aluminum alloy base material d. , hole a... reach a predetermined depth within the base material d, and f in the figure is a barrier layer. After processing, the inner peripheral surface of the pin hole is machined by grinding or polishing to set the pin hole at a predetermined line.

The inner diameter surface e of the pin hole obtained above has a much higher hardness than the base material, and has excellent wear resistance by itself. In addition, a large number of minute holes a... are formed on the inner diameter surface eK, and an oil intake port 1 is formed in a part of the connecting rod small end 122.
23, and 4 between the pin 13 and the bottle hole 104.
Due to the existence of a gap of 1J, although the gap is small, the oil in the fuel permeates the inner periphery of the bottle hole 104, and is stored and held in the hole portion a. Therefore, the inner diameter portion of the pin hole itself has self-lubricating properties, and due to the mutual effect of improved wear resistance due to film formation and increased lubricity, the wear resistance is significantly improved compared to conventional pin holes.

Although aluminum anodization treatment has been described in the embodiment, a porous coating may be formed by reverse electroplating treatment on the inner surface of a hard metal such as chromium.

As is clear from the above, according to the present invention, it is possible to improve wear resistance and lubricity by forming a hard and porous broken membrane on the inner circumferential surface of the piston pin hole. The diameter can be made as thin as possible, reducing engine vibration and reducing weight.

The present invention has the advantages as described above.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view of the main parts of the engine, Figures 2 and 3 are explanatory enlarged sectional views of the bottle hole showing the state after coating formation and internal diameter machining, and Figure 3 is the source of the material. FIG. 4 is a longitudinal sectional view of the engine in another direction. In the drawing, 10 is a binuton, 104 is a bottle hole, 11 is a crankshaft, 13 is a piston pin, and 12 is a connecting rod.

Claims (1)

[Claims] In an internal combustion engine comprising a piston slidably fitted in a cylinder hole, a piston pin rotatably fitted in a pin hole provided in a skirt portion of the piston, and a connecting rod connecting the piston pin and a crankshaft, A piston for an internal combustion engine, characterized in that the piston is made of an aluminum alloy, and a porous wear-resistant coating is formed on the inner peripheral surface of the piston pin hole.