JPH06137209A - Cylinder liner - Google Patents

Abstract

PURPOSE:To satisfy wear resistance and seizure resistance even in a material not containing graphite as a lubricant in its structure, thereby to achieve thickness reduction with a high-strength, high-hardness material by forming a large number of recessed parts each having a specific width and length on the inner circumferential surface of a cylinder liner. CONSTITUTION:A cylinder liner 10 of an internal combustion engine is provided with a large number of recessed parts 11 having a width of 5 to 1000mum and a length of 5mum or more on its inner circumferential surface. The recessed parts 11 are formed by laser beams. The recessed parts 11 may be formed by the continuation of grooves, or by juxtaposing, for example, a large number of holes on the one surface of the cylinder liner, or by forming these holes at random. The shape of the recessed part 11 is not especially restricted. Thereby, a lubricant can be retained in the recessed parts 11, so that even in a material not containing graphite in its structure such as cast iron, wear resistance and seizure resistance can be satisfied. Thus, by using a material of higher strength and higher hardness than cast iron, thickness reduction can be achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder liner for internal combustion engines such as gasoline engines and diesel engines.

[0002]

2. Description of the Related Art A cylinder liner used for the inner peripheral surface of a cylinder of an internal combustion engine must slide against a piston ring and maintain airtightness. Baking resistance and corrosion resistance are required. Further, in terms of machining, it is required to have a hardness H _R B (Rockwell B) of about 100.

Conventionally, for this purpose, a special cast iron having graphite in its structure and containing Cr, B, P, Mo and the like has been used as a cylinder liner material. In such cast iron, as shown in FIG. 4, graphite 2 in the structure is deposited on the surface of the liner 1 in the form of flakes having a length of 50 to 200 μm and a width of 5 to 10 μm. Since the flake graphite 2 serves as a lubricant and serves as an oil reservoir, it is relatively inexpensive and
The above requirements can be met.

[0004]

In recent years, in order to reduce the weight of the engine, it is required to reduce the thickness of the cylinder liner. However, in order to satisfy the above requirements using cast iron, the wall thickness is limited to about 1.2 mm, and if it is made thinner than this, there is a problem in terms of strength. On the other hand, it is possible to use a hard material other than cast iron (for example, steel), but in this case, unlike cast iron, there is no flake graphite that acts as a lubricant on the surface, so seizure is likely to occur. There is a problem.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a cylinder liner which is thin and which can satisfy wear resistance, seizure resistance, and corrosion resistance. Especially.

[0006]

The cylinder liner of the present invention is characterized in that a large number of recesses having a width of 5 to 1000 μm and a length of 5 μm or more are formed on the inner peripheral surface. It is desirable that the recess be formed by laser light.

[0007]

The lubricant can be held in the recess formed on the surface of the cylinder liner, which is a sliding surface. In this way, even a material such as cast iron that does not have graphite in its structure can satisfy wear resistance and seizure resistance. Therefore, since the selection range of the cylinder liner material is expanded, it is possible to use a material with higher strength than cast iron,
Thinning can be achieved.

Although the size of the recess is similar to that of flake graphite, such a recess can be easily formed by using a laser.

[0009]

The cylinder liner of the present invention will be described below. The recess formed on the surface of the liner may be continuously formed in a groove shape like the cylinder liner 10 shown in FIG. 1 (the recess is indicated by 11), or the cylinder liner shown in FIG. Liner 12 like 12
A large number of holes 13 may be formed on the entire surface. When the concave portion is composed of a large number of holes, the concave portions may be formed so as to be aligned in one direction, as shown in FIG.
It may be randomly formed without directivity. Also,
The shape of the recess at this time is not particularly limited.

The size of the recess is similar to that of flake graphite in a cast iron cylinder liner. That is, according to the cross-sectional view of FIG. 3, the width W of the recess 15 is about 5 to 1000 μm, and the length L is 5 μm or more. The depth D depends on the thickness of the cylinder liner, the processing method of the recess, etc.
Generally, it is about 100 to 300 μm. If a lubricant is previously added to a cylinder liner having such a recess,
The lubricant is retained in the recess and helps improve the seizure resistance of the cylinder liner. Therefore, even if a material such as cast iron that does not have flake graphite that can serve as a lubricant and an oil reservoir is used, the requirement for seizure resistance can be satisfied. This means that the range of choice of cylinder liner material is wider than in the past, and in the past, high hardness that could not be used because it did not have graphite in the tissue,
Allows the use of high strength materials. If a material having higher hardness and higher strength than cast iron is used, it is possible to reduce the thickness and improve the corrosion resistance. For example, when steel having a tensile strength of 40 kg or more is used as the cylinder liner material, the cylinder liner has sufficient strength to withstand a thickness of 1 mm or less.

As a method for forming such a recess for holding a lubricant, a method for easily forming a recess having a desired length, width and depth in a high strength material, for example, a printing method, etching Method, laser processing, etc.
Of these, the method of applying a laser beam is particularly preferable because precise control is possible.

[0012]

Since the cylinder liner of the present invention has the concave portion for holding the lubricant, even if a material such as cast iron that does not contain graphite serving as a lubricant in the structure is used,
The seizure resistance can be satisfied. Therefore, the range of selection of the material of the cylinder liner is wider than in the past, and the use of a material having higher strength and higher hardness than cast iron enables the cylinder liner to be made thinner.

[Brief description of drawings]

FIG. 1 is a schematic view showing a surface of a cylinder liner according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a surface of a cylinder liner according to another embodiment of the present invention.

FIG. 3 is a diagram for explaining the shape of a groove.

FIG. 4 is a schematic view showing a surface of a conventional cylinder liner.

[Explanation of symbols]

 10 Cylinder Liner 11 Recess 12 Cylinder Liner 13 Recess

Claims (2)

[Claims] 1. A cylinder liner characterized in that a large number of recesses having a width of 5 to 1000 μm and a length of 5 μm or more are formed on the inner peripheral surface. 2. The cylinder liner according to claim 1, wherein the recess is formed by laser light.