KR20120071495A

KR20120071495A - Cylinder for engine

Info

Publication number: KR20120071495A
Application number: KR1020100133061A
Authority: KR
Inventors: 강민구
Original assignee: 두산인프라코어 주식회사
Priority date: 2010-12-23
Filing date: 2010-12-23
Publication date: 2012-07-03
Also published as: WO2012086935A2; WO2012086935A3

Abstract

PURPOSE: An engine cylinder is provided to improve the lubricant performance of the inner surface of the cylinder and the lubricant performance of piston rings as fine oil grooves and hardening pattern are formed on the inner surface of the cylinder. CONSTITUTION: An engine cylinder comprises a hardening pattern(21) and a plurality of fine oil grooves(31). A piston moves up and down inside the engine cylinder. A plurality of laser hardening units is separately placed in the hardening pattern. A plurality of the fine oil grooves is formed in the part, in which a plurality of laser hardening parts is not formed. A predetermined part is a contact area for the piston when the piston reaches a top dead center. The hardening pattern is formed within a hardening area(20) formed within a range of 5%~32% distance from the top dead center in a section between the top dead center and a bottom dead center.

Description

Engine Cylinder {CYLINDER FOR ENGINE}

The present invention relates to an engine cylinder, and more particularly to an engine cylinder that can improve the wear resistance of the rings of the cylinder and the piston.

In general, the engine is operated by the piston reciprocating up and down by the combustion pressure generated by the fuel combustion in the combustion chamber inside the engine cylinder. The vertical reciprocating motion of the piston is converted into rotational motion by the crank mechanism. Accordingly, rotational power can be obtained.

In this process, the inner circumferential surface of the cylinder is in friction with the piston ring, which causes wear on the inner circumferential surface and the piston ring of the cylinder. Wear on the inner circumferential surface of the cylinder is mainly caused when the up and down reciprocating piston is located at the top of the cylinder, that is, located at and near the top dead center (TDC).

Referring to FIG. 1, abrasion of the inner circumferential surface of the cylinder occurs mainly in the region where the piston is in contact with the piston when the piston is located at the top dead center, among which the piston top ring and the second ring are located. The most wear occurs at.

This wear lowers engine power, increases fuel consumption, worsens fuel economy, and increases engine oil consumption. If wear is severe, the life of the engine will be shortened.

In order to solve this problem and to protect the cylinder, the engine cylinder block is loaded with a cylinder liner made of special cast iron or steel with excellent surface hardness.However, in a small engine, the cylinder liner is difficult to use due to cost and manufacturing difficulties Even in large engines, the operating environment of the engine is deteriorated due to the strengthening of environmental regulations and the continuous improvement of the engine, and thus there is a disadvantage in that the use of the conventional cylinder liner is limited.

The present invention has been made in view of the above-described problems, and can be minimized the cost and processing time of the cylinder machining process while minimizing the wear of the cylinder and the piston ring by strengthening the wear resistance and lubricity only in the region of the large amount of wear in the inner peripheral surface of the cylinder The purpose is to provide an engine cylinder.

According to the above problem solving means, the hardening pattern which consists of a laser hardening part, and a fine oil groove are formed in the cylinder inner peripheral surface, and the wear resistance and lubricity of the rings of a cylinder inner peripheral surface and a piston are improved.

In addition, the laser hardened portion and the fine oil grooves are formed only in the areas where wear is concentrated, thereby simplifying the process for processing the laser hardened portion and the fine oil grooves, thereby improving the productivity of the cylinder.

In particular, a hardening pattern is formed in a hardened region 5% to 32% from the top dead center of the piston in the section between the top dead center and the bottom dead center of the piston where wear of the cylinder inner circumference is concentrated. The wear resistance can be maximized.

Moreover, since a hardening pattern is formed in several row and the laser hardening part of an adjacent row is mutually shift | deviated, wear resistance can be improved evenly in the whole hardening area | region of the cylinder inner peripheral surface.

In addition, by making the formation area of the hardening pattern 50% to 80% of the hardened area, fine oil grooves can be formed in the hardened area while maximizing wear resistance of the inner circumferential surface of the cylinder by hardening, thereby improving lubricity. Improved lubricity also minimizes the amount of wear on the rings of the piston.

On the other hand, by forming the fine oil groove in the region of 5% to 50% distance from the top dead center of the piston of the interval between the top dead center and the bottom dead center of the piston, it is possible to prevent unnecessary processing of the fine oil groove, thereby In addition to improving productivity, it is possible to prevent excessive consumption of engine oil.

1 is a cross-sectional view schematically showing a general cylinder.
FIG. 2 is a view schematically illustrating a state in which a piston reciprocates inside a cylinder according to an embodiment of the present invention, and compares a piston when it is at a top dead center and a bottom dead center.
FIG. 3 is a developed view showing the hardened region in the cylinder inner circumferential surface of FIG. 2.
FIG. 4 is a development view schematically illustrating a hardening region and a groove processing region of the inner circumferential surface of FIG. 2.
5 is a graph showing the wear amount of the cylinder inner peripheral surface and the piston ring in Examples, Comparative Examples 1 to 3.

Hereinafter, an engine cylinder according to an embodiment of the present invention will be described in detail.

2, in the engine cylinder according to the exemplary embodiment of the present invention, the piston 10 reciprocates in an up and down direction therein. The piston 10 has a top ring or a first ring (11, top ring), the second ring (12, second ring), the oil ring 13 is formed to be spaced apart from each other in the vertical direction to inject the oil into the combustion chamber It prevents oil from scraping off the inner circumference of the cylinder. In addition, the distance between the top dead center and the bottom dead center of the piston 10 is called a stroke or a stroke section.

The inner circumferential surface of the cylinder is in friction with the first ring 11, the second ring 12, and the oil ring 13. As described above, the wear caused by the frictional movement occurs most frequently in the region in contact with the piston when the piston 10 is at the top dead center of the cylinder inner circumferential surface. In particular, wear is concentrated in the region where the first ring 11 and the second ring 12 contact. Therefore, in order to minimize the amount of abrasion, when the piston 10 is at the top dead center, the area around the cylinder inner circumferential surface of the area where the piston is located, more preferably the area where the first and second rings 11 and 12 contact each other. The structure should be improved.

As a result of the measurement, when the piston 10 is at the top dead center, the inner circumferential surface of the cylinder in contact with the first ring 11 and the second ring 12 is 32 at the top of the stroke from 5% of the stroke at the top dead center. The area between points which is%. In this embodiment, as shown in FIG. 3, such a region is set as the curing region 20 and a plurality of laser curing portions 22 are formed in the curing region 20.

Referring to FIG. 3, in the hardened region 20 of the inner circumferential surface of the cylinder, a plurality of laser hardened portions 22 are disposed to be spaced apart from each other in the circumferential direction (X-axis direction) and the piston movement direction (Y-axis direction). ) Is formed. In the present invention, the curing pattern 21 means a pattern formed by the plurality of laser curing units 22 on the laser curing region 20.

More specifically, the cured pattern 21 may include a first row in which the plurality of laser curing parts 22 are spaced apart from each other in the circumferential direction (X-axis direction), and the first row and the piston movement direction (Y-axis). Direction) spaced apart in the second row, the third row formed spaced apart from the second row and the piston movement direction (Y-axis direction), and the third row spaced apart from the third row and the piston movement direction (Y-axis direction). And a fourth row that is formed. In the present embodiment, it has been described that the four rows are arranged, but the number of one row constituting the plurality of rows may be changed according to engine specifications such as the capacity of the cylinder.

On the other hand, the laser hardening parts 22 of adjacent rows mutually shift | deviate and have a zigzag arrangement behavior. As an example, the laser curing unit 22 in the first row and the laser curing unit 22 in the second row are arranged in a zigzag form while being shifted in the circumferential direction (X-axis direction). The laser curing unit 22 may be formed through a mask having the same shape as that of the curing pattern 21, but may be formed by various other methods. In addition, in the present exemplary embodiment, the laser curing unit 22 is formed to have a rectangular shape, but the shape of the laser curing unit 22 may be configured in various shapes such as a dimple shape.

On the other hand, it is preferable that the area which the laser hardening part 22 occupies is 50% or more and 80% or less of the area of the hardening area | region 20. As shown in FIG. If less than 50% of the area of the hardened region 20 occupied by the laser hardened portion 22, the effect of hardening does not appear well, and if it is 80% or more, the space for forming the fine oil groove 31 to be described later is insufficient. This is because the amount of wear of the first ring 11 and the second ring 12 is increased. Moreover, it is preferable that the hardening depth of the laser hardening part 22 is within 0.4 mm. This is substantially to reduce the unnecessary machining because the cylinder inner peripheral surface is less likely to wear more than 0.4 mm to improve productivity as well as to minimize the deformation of the cylinder inner peripheral surface.

In this embodiment, the laser curing unit 22 is formed by laser irradiation. In order to improve hardness, high frequency heat treatment can be used, but high frequency heat treatment may cause deformation of the inner circumferential surface of the cylinder during processing and not easy to control the depth of heat treatment. There are also disadvantages. In addition, a method of forming a nitride layer by performing nitriding heat treatment on the inner circumferential surface of the cylinder, or forming a coating and plating layer may be used. There are also disadvantages that the processing process is complicated and takes a lot of time. For this reason, it is preferable to use the hardening treatment method for laser irradiation which can harden | cure a specific depth only to the hardening area | region 20 which is a wear-rich area.

Meanwhile, the distance between the first ring 11 and the oil ring 13 corresponds to a distance of 5% to 50% with respect to the stroke section from the top dead center, and this area is grooved as shown in FIG. 4. The area 30 was set. In FIG. 4, the fine oil groove 31 is formed in an area of less than 5% of the stroke from the top dead center, but preferably, the fine oil groove 31 is formed in the area of 5% or more.

In the groove processing region 30, the fine oil groove 31 is formed to allow the engine oil to be supplied to stay for a predetermined time, thereby improving lubrication performance. That is, the hardness of the laser is increased by the laser hardening part 22 to improve wear resistance, and the lubrication performance is improved by the fine oil groove 31 so that the inner circumferential surface of the cylinder, the first and second rings 11, 12, and the oil ring ( 13) minimized the amount of wear. Particularly, the fine oil groove 31 is processed in a portion of the groove processing region 30 in which the laser curing portion 22 is not formed in the curing region 20. Although the hardening pattern and the fine oil groove may be overlapped with each other, when the fine oil groove is overlapped with the hardening pattern, processing may be difficult, and when the hardening pattern is overlapped with the fine oil groove, the processed shape may be clumped.

The depth of the fine oil groove 31 is preferably greater than 0 mm and less than or equal to 0.4 mm, which does not further improve abrasion resistance even when the depth of the fine oil groove 31 exceeds 0.4 mm. This is because the amount of oil staying increases to increase the consumption of engine oil. The fine oil groove 31 may also be formed by a laser processing method, but various processing methods other than laser processing may be used as necessary.

Meanwhile, referring to FIG. 5, four tests were performed to confirm wear resistance of the cylinder according to the present embodiment.

Comparative Example 1 was a wear test of the general cylinder was not processed, Comparative Example 2 was a wear test of the cylinder formed only the fine oil groove 31, Comparative Example 3 was a wear test with the cylinder only laser curing treatment, Example The wear test was performed with a cylinder in which a fine oil groove 31 and a laser hardened portion 22 were formed.

As shown in FIG. 5, it can be seen that the embodiment significantly reduced the amount of wear of the first ring 11, the second ring 12 and the oil ring 13 as well as the amount of wear of the inner circumferential surface of the cylinder from Comparative Examples 1 to 3. Can be.

On the other hand, in the present embodiment has been illustrated that the laser curing portion 22 and the fine oil groove 31 is formed on the inner peripheral surface of the cylinder, the cylinder used in the concept including a cylinder liner, laser curing portion 22 to the cylinder liner ) And the fine oil groove 31 are also included in the spirit of the present invention.

10; Piston 20; Hardened area
21; Cured pattern 22; Laser Curing Part (22)
30; Grooving zone 31; Fine oil groove

Claims

As an engine cylinder in which the piston 10 vertically reciprocates,
(I) the hardening pattern 21 in which the some laser hardening part 22 hardened by the laser was arrange | positioned spaced apart from each other in the predetermined area | region of the inner peripheral surface; And (ii) a plurality of fine oil grooves 31 formed in a portion where the plurality of laser curing portions 22 are not formed,
The predetermined area is an area in contact with the piston when the piston 10 reaches a top dead center.
An engine cylinder characterized in that.

The method of claim 1,
The hardening pattern (21) is an engine cylinder, characterized in that formed in the hardened region (20) of 5% to 32% distance from the top dead center of the piston of the interval between the top dead center and the bottom dead center of the piston.

The method of claim 2, wherein the cured pattern 21,
A first row in which the plurality of laser curing portions 22 are spaced apart from each other in the circumferential direction (X-axis direction),
A second row disposed to be spaced apart from the first row in a movement direction (Y-axis direction) of the piston 10, and the plurality of laser curing units 22 disposed to be spaced apart from each other in a circumferential direction (X-axis direction) Including;
And the laser curing section (22) in the first row and the laser curing section (22) in the second row are arranged to be offset from each other.

The method of claim 2,
The area in which the hardening pattern (21) is formed is an engine cylinder, characterized in that 50% to 80% of the area of the hardened region (20).

The method of claim 1,
The curing depth of the laser curing portion 22 is an engine cylinder, characterized in that larger than 0 mm and smaller than 0.4 mm.

The method of claim 1,
The plurality of fine oil grooves 31 are formed in the groove processing region 30 at a distance of 5% to 50% from the top dead center of the piston among the top dead center and the bottom dead center of the piston 10. Engine cylinder.

The method of claim 1,
An engine cylinder, characterized in that the depth of the fine oil groove 31 is greater than 0 mm and less than 0.4 mm.