JP2021032171A - Piston of internal combustion engine, and internal combustion engine - Google Patents

Abstract

To provide a piston of an internal combustion engine having a coating layer with higher lubricant holding capacity, and an internal combustion engine.SOLUTION: A piston 100 applied to an internal combustion engine is configured such that on the surface of a skirt part 120 extending below a piston ring, a coating layer 121 is formed, and the coating layer 121 has, in an outer edge region of the surface of the skirt part 120, an outer frame part 121a formed so as to surround a central region of the surface of the skirt part 120, and a plurality of pattern parts 121b formed apart from each other in the central region of the surface of the skirt part 120.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to pistons of internal combustion engines and internal combustion engines.

Conventionally, a piston of an internal combustion engine is known.

This type of piston is generally provided with a skirt portion that extends below the piston ring. By sliding contact with the inner wall of the cylinder, the skirt portion suppresses the swinging motion of the piston (the swinging motion to the left and right around the piston pin) during the reciprocating motion in the cylinder. Therefore, if the frictional resistance on the surface of the skirt portion is large, the sliding load during the reciprocating motion of the piston increases, causing problems such as reduced fuel consumption and wear.

In the piston according to the prior art, the frictional characteristics between the skirt portion and the inner wall of the cylinder are improved by forming a coating layer on the surface of the skirt portion (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2009-052450

By the way, in the piston according to the prior art, there is a problem that it is difficult to maintain the frictional characteristics of the skirt portion for a long period of time because the coating layer is worn by continuous use.

In the piston according to the prior art, in order to solve such a problem, a configuration in which a region in which a coating layer is formed and a region in which a coating layer is not formed is provided on the surface of the skirt portion is being studied (for example, See Patent Document 1). With such a configuration, the region where the coating layer is not formed becomes a recess and functions as a lubricating oil holding region, so that the frictional characteristics of the skirt portion can be improved.

However, in the piston according to the prior art, there is room for improvement in the form of the coating layer in order to maximize the lubricating oil holding capacity.

The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide a piston of an internal combustion engine having a coating layer having a higher lubricating oil holding capacity, and an internal combustion engine.

The main disclosure that solves the above-mentioned problems is
A piston used in an internal combustion engine
A coating layer is formed on the surface of the skirt portion extending below the piston ring.
The coating layer is formed in the outer edge region of the surface of the skirt portion, the outer frame portion formed so as to surround the central region of the surface of the skirt portion, and the central region of the surface of the skirt portion so as to be separated from each other. Has a plurality of pattern parts,
It is a piston.

Also, in other aspects,
An internal combustion engine having the above piston.

According to the present disclosure, it is possible to realize a piston having a higher lubricating oil holding capacity.

The figure which shows the whole structure of the internal combustion engine to which the piston which concerns on one Embodiment is applied Front view of the piston according to one embodiment Sectional drawing which shows the internal structure of the piston which concerns on one Embodiment Side view of the piston according to one embodiment

Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same function are designated by the same reference numerals, so that duplicate description will be omitted.

Each figure shows a common Cartesian coordinate system (X, Y, Z) in order to clarify the positional relationship of each configuration. In the following, the positive direction of the Z-axis represents the side where the combustion chamber of the piston is formed (hereinafter, referred to as "upward direction"), and the negative direction of the Z-axis is the bottom side of the piston (hereinafter, "downward"". It will be described as representing (referred to as).

[Overall configuration of piston]
Hereinafter, an example of the overall configuration of the piston according to the embodiment will be described with reference to FIGS. 1 to 3.

FIG. 1 is a diagram showing an overall configuration of an internal combustion engine E to which the piston 100 according to the present embodiment is applied.

The internal combustion engine (here, diesel engine) E includes, for example, a cylinder block B, a piston 100 slidably inserted in the cylinder block B, a cylinder head portion T held above the cylinder block B, and a cylinder. The injector I held by the head portion T is provided.

FIG. 2 is a front view of the piston 100 according to the present embodiment, and FIG. 3 is a cross-sectional view showing an internal configuration of the piston 100 according to the present embodiment.

The piston 100 is housed in the cylinder block B so as to be reciprocating in the vertical direction. The piston 100 typically has a cylindrical shape.

The piston 100 includes a crown portion 110, a skirt portion 120 extending below the piston 100 from the outer peripheral surface 110b of the crown portion 110, and a pin boss portion 130 extending below the piston 100 from the outer peripheral surface 110b of the crown portion 110. I have.

The crown portion 110 is a head portion of the piston 100, a combustion chamber 111 is formed in the central region of the top portion 110a of the crown portion 110, and a hollow oil gallery 112 is formed in the crown portion 110. A piston ring groove 113 is formed on the outer peripheral surface 110b of the crown portion 110.

Three piston ring grooves 113 are formed in an annular shape. The three piston ring grooves 113 are a first compression ring groove, a second compression ring groove, and an oil ring groove, respectively, from the upper side. A compression ring (not shown) is fitted into each of the first and second compression ring grooves, and an oil ring (not shown) is fitted into the oil ring groove. The oil ring groove is formed with an oil drain hole 113a that communicates the oil ring groove with the inside of the piston 100.

The skirt portion 120 is a pair of wall-shaped members extending below the piston 100 from the outer peripheral surface 110b of the crown portion 110 and arranged on both sides in the ± Y direction with the piston pin 200 interposed therebetween. The skirt portion 120 extends in the vertical direction substantially parallel to the central axis of the piston 100, and the cross-sectional shape of the skirt portion 120 in the lateral direction is an arc shape. The skirt portion 120 forms a hollow portion 120a below the crown portion 110 so that the connecting rod 300 connected to the piston pin 200 can move inside the piston 100 as the piston 100 moves up and down.

By sliding contact with the inner wall of the cylinder block B, the skirt portion 120 suppresses the swinging motion of the piston 100 (the swinging motion to the left and right centering on the piston pin 200) during the reciprocating motion in the cylinder block B. .. A coating layer 121 is formed on the surface of the skirt portion 120 (that is, the outer surface) in order to realize good friction characteristics between the skirt portion 120 and the inner wall of the cylinder block B (FIG. 4). See below).

The pin boss portion 130 extends below the piston 100 from the outer peripheral surface 110b of the crown portion 110. A pair of pin boss portions 130 are arranged so as to sandwich the hollow portion 120a formed by the skirt portion 120. The pin boss portion 130 has a pin fitting hole 130a at a position facing the hollow portion 120a, and supports the piston pin 200 in the pin fitting hole 130a. The pin boss portion 130 has a shape recessed inward with respect to the cylindrical shape forming the outer shape of the piston 100 so as to be separated from the inner wall of the cylinder block B.

The piston pin 200 is inserted into a pin fitting hole 130a formed in the pin boss portion 130 and a small end hole 330 of the connecting rod 300, and rotatably supports these. That is, the piston pin 200 connects the piston 100 and the connecting rod 300.

The connecting rod 300 has small end portions 320 and large end portions (not shown) having different sizes at both ends of the shaft portion 310. The small end portion 320 is formed with a small end hole 330 having an inner diameter through which the piston pin 200 can be inserted. Further, a large end hole through which a crank pin for connecting a connecting rod 300 and a crankshaft (not shown) can be inserted is formed in the large end portion.

The piston 100 is manufactured by a known method such as casting or forging a known material such as an aluminum-silicon alloy, an aluminum-copper alloy, a titanium alloy, iron, or steel.

[Detailed composition of coating layer]
Next, with reference to FIG. 4, the detailed configuration of the coating layer 121 formed on the surface of the skirt portion 120 of the piston 100 according to the present embodiment will be described.

FIG. 4 is a side view of the piston 100 according to the present embodiment. FIG. 4 shows the detailed configuration of the coating layer 121 according to the present embodiment. In FIG. 4, the piston pin 200 and the connecting rod 300 are not shown.

The coating layer 121 reduces the frictional resistance of the skirt portion 120 that slides against the inner wall of the cylinder block B when the piston 100 reciprocates. The coating layer 121 is formed of a resin having low friction resistance, such as a polyamide resin, an epoxy resin, or a phenol resin. In addition, the coating layer 121 may be formed of a solid lubricant such as graphite, synthetic mica, or talc.

The coating layer 121 has an outer frame portion 121a and a plurality of pattern portions 121b. The region on the surface of the skirt portion 120 where the coating layer 121 is not formed is a recess.

The outer frame portion 121a is formed in the outer edge region of the surface of the skirt portion 120 so as to surround the central region of the surface of the skirt portion 120. The outer frame portion 121a has, for example, a substantially rectangular shape, and is formed along the outer edge region of the surface of the skirt portion 120.

The outer frame portion 121a functions to hold the lubricating oil in the recess inside the outer frame portion 121a.

The plurality of pattern portions 121b are formed in the central region of the surface of the skirt portion 120 so as to be separated from each other. The plurality of pattern portions 121b are arranged in a staggered pattern inside, for example, the outer frame portion 121a. Further, each pattern portion 121b has, for example, an elliptical shape in which the direction in which the piston 100 reciprocates is the minor axis direction. It is desirable that each pattern portion 121b is formed so that the outer shape is 3 cm or less.

The plurality of pattern portions 121b form an uneven shape on the surface of the skirt portion 120, and suppress the lubricating oil from moving to the outside of the outer frame portion 121a of the coating layer 121 with the reciprocating motion of the piston 100. That is, the plurality of pattern portions 121b function to enhance the holding ability of the lubricating oil in the recesses inside the outer frame portion 121a of the coating layer 121.

In the piston according to the prior art, this type of coating layer is formed so as to cover the entire surface of the skirt portion. The non-coated region is formed in a dot shape so as to partially hollow out the coating layer (see, for example, Patent Document 1).

Even in the arrangement mode of the coating layer according to the prior art, the holding ability of the lubricating oil can be exhibited. However, depending on the arrangement mode of the coating layer according to the prior art, the lubricating oil remains only in the dot-shaped non-coated region, so that the lubricating oil is used when the piston reciprocates up and down. Easy to dissipate from the surface of the part.

In this respect, the coating layer 121 according to the present embodiment is disposed inside the outer frame portion 121a while holding the lubricating oil in the recess inside the outer frame portion 121a at the outer frame portion 121a. The plurality of pattern portions 121b suppress the movement of the lubricating oil up and down. Therefore, according to the arrangement mode of the coating layer 121 according to the present embodiment, it is possible to realize a high holding ability of the lubricating oil as compared with the arrangement mode of the coating layer according to the prior art.

In particular, the plurality of pattern portions 121b of the coating layer 121 according to the present embodiment are arranged in a staggered manner, and each pattern portion 121b has an elliptical shape in which the direction in which the piston 100 reciprocates is the minor axis direction. .. As a result, when the piston 100 reciprocates up and down, the moving distance when the lubricating oil dissipates from the surface of the skirt portion 120 in the vertical direction can be increased, so that a higher holding capacity of the lubricating oil can be obtained. It can be realized.

In addition, in the arrangement mode of the coating layer 121 according to the present embodiment, the region itself of the coating layer 121 formed in the surface of the skirt portion 120 can be reduced. Normally, when the piston 100 reciprocates up and down, the coating layer 121 of the skirt portion 120 comes into contact with the inner wall of the cylinder block B. That is, by reducing the area of the coating layer 121 as in the coating layer 121 according to the present embodiment, it is possible to reduce the area where the piston 100 comes into contact with the inner wall of the cylinder block B and reduce the friction loss. Become.

(Other embodiments)
The present invention is not limited to the above embodiment, and various modifications can be considered.

In the above embodiment, an elliptical shape is shown as an example of the shape of the pattern portion 121b of the coating layer 121. However, in the present invention, various shapes such as a circular shape or a quadrangular shape may be adopted as the shape of the pattern portion 121b.

Further, in the above embodiment, a diesel engine is shown as an example of the configuration of the internal combustion engine E. However, the internal combustion engine E to which the piston 100 according to the present invention is applied may be gasoline engine. The application target of the internal combustion engine E is also arbitrary, such as a vehicle or a ship.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples illustrated above.

According to the present disclosure, it is possible to realize a piston having a higher lubricating oil holding capacity.

E Internal combustion engine 100 Piston 110 Crown part 110a Top 110b Outer peripheral surface 111 Combustion chamber 112 Oil gallery 113 Piston ring groove 120 Skirt part 120a Hollow part 121 Coating layer 121a Outer frame part 121b Pattern part 130 Pin boss part 130a Pin fitting hole 200 Piston pin 300 Connecting rod 310 Shaft 320 Small end 330 Small end hole

Claims (4)

A piston applied to an internal combustion engine
A coating layer is formed on the surface of the skirt portion extending below the piston ring.
The coating layer is formed in the outer edge region of the surface of the skirt portion, the outer frame portion formed so as to surround the central region of the surface of the skirt portion, and the central region of the surface of the skirt portion so as to be separated from each other. Has a plurality of pattern parts,
piston. Each of the pattern portions of the plurality of pattern portions has an elliptical shape with the direction in which the piston reciprocates as the minor axis direction.
The piston according to claim 1. The plurality of pattern portions are arranged in a staggered pattern.
The piston according to claim 1 or 2. The internal combustion engine provided with the piston according to any one of claims 1 to 3.

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