JP2003231936A - Cylinder liner of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylinder liner of an engine, which has the improved strength and abrasion resistance, has the reduced manufacturing cost, and is lightweightened. <P>SOLUTION: In the cylinder liner that is cast-embedded in the cylinder block of the engine, and has a sliding surface on which a piston can slide, formed on the inner surface, the cylinder liner consists of an Al alloy containing Al, Si and Cu as essential components, and at least either one element of Mn and Sn, wherein hardness of the matrix of the Al alloy is 70 HV or higher. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder liner made of an aluminum alloy that is cast into a cylinder block of an engine.

[0002]

2. Description of the Related Art The weight reduction of engines has been promoted along with the increase of environmental problems, and the material characteristics of sliding parts of engine parts are required to be lightweight and wear resistant. For example, as the cylinder liner, a cylinder liner having a cast-wrap structure capable of reducing weight has been put into practical use. The cast-in structure cylinder liner is formed of a cylindrical aluminum alloy, the outer peripheral surface of which is cast-in by a cylinder block made of an aluminum alloy die-cast molding, and the inner peripheral surface of the cylinder liner is hard-coated. .

FIG. 5 is a diagram schematically showing a cross section of a cylinder block of a multi-cylinder engine. In each cylinder of the cylinder block 11 of the multi-cylinder engine 10 shown in FIG. 5, a cylindrical cylinder bore 12 in which a piston can slide is formed, and a cylinder liner 13 is provided in each cylinder bore 12 with a cast-in portion 14.
Is cast and formed. Furthermore, the cylinder liner 13
A hard plating film 15 is formed on the inner peripheral surface of the plate by plating.

The cylinder liner having the cast-in structure is shown in FIG.
It is produced by the process procedure shown in. First, an Al alloy material was prepared as a base material for the cylinder liner. The specific components of the Al alloy material are as follows:
~ 10.5, Fe: 0.5, Cu: 2.5-3.5, M
g: 0.5 to 0.8, Mn: 0.3, Cr: 0.2, Z
It contains n: 0.2 and the balance is Al and unavoidable impurities.

As shown in FIG. 6, first, the components of the Al alloy material are adjusted, heated and softened, and then a continuous hollow cylindrical tubular body is produced by extrusion molding, and the produced hollow cylindrical tubular body is produced. Was cut to form a material for the cylinder liner (step 1).

After subjecting the material of the cylinder liner to heat solution treatment, water quenching, aging heat treatment, and then natural cooling, surface hardening treatment was applied to the material of the cylinder liner (step 2).

After the surface hardening treatment, the electric conductivity of the obtained cylinder liner was inspected (step 3). After the end surface and inner surface of the cylinder liner have been processed smoothly, the outer surface of the cylinder liner is processed as necessary (step 4), the cylinder liner is attached to the die of the cylinder block, and the die is cast with aluminum die casting alloy. It was molded (step 5). After smoothing the inner surface of the cylinder liner by mechanical grinding (step 6), cleaning with acid, degreasing with alkali, and forming an alumite film as a base treatment, Ni-
Dispersion plating of P-SiC was performed (step 7). Honing is applied to the inner surface of the cylinder liner to finish it to precise dimensional tolerances (step 8).

The cylinder liner manufactured by the above manufacturing method has a sliding surface formed by plating the inner peripheral surface thereof, and ensures the wear resistance that allows the cylinder to slide.

[0009]

However, the conventional cylinder liner has improved wear resistance because the inner peripheral surface thereof is plated, but on the other hand, the plating process increases the number of manufacturing steps and Becomes complicated,
This has caused the manufacturing cost of the cylinder block to soar.

Therefore, a method for improving the wear resistance of the Al alloy itself which forms the cylinder liner without performing the plating treatment has been devised. For example, there is a method in which the Al alloy is subjected to a hardening treatment to increase the surface hardness to improve the strength and wear resistance of the Al alloy itself. Although it is possible to increase the surface hardness of the Al alloy by hardening the Al alloy,
When manufacturing a cylinder liner with a cast-in structure for the purpose of weight reduction, as described above, the heat during casting of the cylinder liner raises the temperature to a high temperature. The hardness of the Al alloy was changed by the annealing effect due to heat during casting, and the hardness of the Al alloy was lowered due to the change in the structure. Therefore,
The hardening treatment of the Al alloy performed before the casting was not able to obtain a substantial effect. As a result, there is a problem that a cylinder liner excellent in both strength and wear resistance cannot be obtained.

The present invention has been made to solve the above problems, and it is an object of the present invention to improve the strength and wear resistance, reduce the manufacturing cost, and provide a lightweight cylinder liner for an engine. And

[0012]

In order to solve the above-mentioned object, various studies have been conducted on the material forming the cylinder liner. For example, a cylinder liner has been developed in which an element such as Fe or Cu is added to an Al alloy material to improve the strength and prevent deterioration of hardening. However, although the addition of Fe can prevent the surface hardness from decreasing, on the contrary, the wear resistance decreases under a specific condition. Therefore, a cylinder liner excellent in both strength and wear resistance cannot be obtained.

FIG. 7 shows an Al--Mg--Si system alloy A.
An Al alloy material containing 60% by mass of 25% Si (referred to as "Base alloy"), and an Al alloy material containing 4% Fe in this Base alloy (referred to as "Base alloy + 4% Fe") It is the figure which compared the hardness with.
In addition, "Base alloy" and "Base alloy + 4% F
For each alloy of "e", the hardness of the extruded material (T1) and the hardness after casting (A) were measured, and the measurement results are shown.

As shown in FIG. 7, the hardness of the extruded material (T1) of "Base alloy" was remarkably lowered after casting (A), whereas the extruded value of "Base alloy + 4% Fe" was extruded. The material (T1) did not show a decrease in hardness even after casting (A). As a result of various studies on this cause, Al
When Fe is contained in the alloy, a metal binding compound β-AlFeSi is crystallized in the alloy structure, and crystallized β-AlFeS
i is dispersed in the Al alloy to strengthen the Al alloy and improve the surface hardness of the Al alloy. As a result, Al containing Fe is added.
It has been found that the alloy can prevent a decrease in hardness even after casting.

However, when Fe was contained in the Al alloy, the strength after casting was secured, but under certain limited wear test conditions, β-AlFe was contained in the Al alloy.
It was found that when a large amount of Si crystallized, the wear resistance was significantly reduced.

Then, various studies were conducted to prevent the deterioration of wear resistance. Usually, not only the hardness of the Al alloy itself to be measured but also Si particles and intermetallic compound β-AlFeSi dispersed in the Al alloy were measured. When the hardness of the removed portion, that is, the hardness of the matrix of the Al alloy was measured, it was found that the hardness of the matrix was deeply involved in the wear resistance of the Al alloy, and the present invention was completed.

That is, according to the present invention, in a cylinder liner that is cast in a cylinder block of an engine and has a sliding surface on which the piston can slide, the cylinder liner is essentially made of Al, Si and Cu. And an Al alloy containing at least one element of Mn and Sn, and the hardness (Vickers hardness) of the matrix component in the Al alloy is 70 HV or more. .

According to the present invention, the matrix quenching is promoted during the extrusion molding of the cylinder liner, and the matrix is solid-solution hardened or age hardened to prevent the age softening during casting of the cylinder block. By setting the thickness to 70 HV or more, it is possible to obtain a cylinder liner excellent in both wear resistance and strength. Further, according to the present invention, since the plating process is unnecessary, it is possible to reduce the manufacturing cost.

In the above invention, the Al alloy is mass%
In addition, Si: 20 to 30, Cu: 0.05 to 2.0 are essential components, and Mn: 0.05 to 4.0 or S.
It is desirable that at least one of n and 0.01 to 4.0 is contained, and the balance is Al and inevitable impurities.

According to the present invention, the late aging element Mn
Alternatively, by containing at least one element of Sn, overaging softening can be suppressed.

Mn in an Al alloy in a mass% of 0.05 to
This is because the effect was not obtained when the Mn content was 0.05%, and the heat treatment property was impaired when the Mn content exceeded 4.0. Further, Sn was contained in the Al alloy in an amount of 0.01 to 4.0 by mass%, but the Sn content was 0.0.
This is because if it is less than 1%, the effect cannot be obtained, and conversely, if it exceeds 4.0, embrittlement occurs.

In the above invention, it is also preferable that the Al alloy contains, by mass%, Al ₂ O ₃ having a particle size of 2 μm or less.

According to the present invention, by including 10% or less of alumina (Al ₂ O ₃ ) in the Al alloy in mass%, the hardness of the matrix can be set to a value of 70 HV or more.

Further, in the above invention, the Al alloy is, in mass%, Mg: 0.1 to 1.5, Ni: 1.0 to 4.
0, Cr: 0.3 or less and Fe: 2% or less, and an intermetallic compound β-AlFeS that crystallizes on the sliding surface when Fe is contained.
The area occupied by i is preferably 5% or less with respect to the total area of the sliding surface.

According to the present invention, Mg, Ni, Cr and Fe are added, if necessary, in order to improve hardenability and aging characteristics.
May contain any one or more elements of, for example,
In mass%, Mg: 0.1-1.5, Ni: 1.0-4.
0, Cr: It is preferable to contain Cr in the range of 0.3 or less. Here, the content of Cr is limited to 0.3 or less, but if Cr is contained in the alloy, the hardenability is hindered, and therefore press quenching cannot be promoted during extrusion molding.

When Fe is contained, the intermetallic compound β-AlFeSi crystallizes in the Al alloy, but β-AlF
If the amount of crystallized eSi increases, the wear resistance decreases, so
In the present invention, the area occupied by the intermetallic compound β-AlFeSi is defined as 5% or less with respect to the total area of the sliding surface.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a cylinder liner cast in a cylinder block of the present invention will be described with reference to Examples 1 to 5 and Comparative Examples 1 to 4.

Examples 1 to 5 (Table 1) In this example, a cylinder liner was prepared in which the composition of the Al alloy was adjusted and the hardness of the alloy matrix was 70 HV or more.

First, the composition of the Al alloy material of the cylinder liner was adjusted. As shown in Table 1, Examples 1 to 3
The composition of the components in mass% is Si: 20 to 30, Cu:
0.05 to 2.0 as an essential component, Mn: 0.05 to
4.0, Sn: 0.05 to 4.0, Mg: 0.1 to 1.
5, Ni: 1.0 to 4.0 and Cr: 0.3 or less. Further, in Example 5, Al ₂ O ₃ having a particle size of 2 μm or less is contained in the Al alloy material.

[0030]

[Table 1] The prepared Al alloy material was melted and cooled at a cooling rate of 10 ² K or more per second by an air atomizing method to prepare a rapidly solidified powder. The rapidly solidified powder was collected, sorted, and then inspected.

Next, the rapidly solidified powder was filled in a rubber mold, subjected to cold isostatic pressing (CIP), and then vacuum sintered to prepare a billet. The prepared billet is 425-520
After heating and softening at a temperature of ℃, it was extruded to form a continuous hollow cylindrical tube. Then, the hollow cylindrical tube was cut to form a material for the cylinder liner.

The material of the cylinder liner was subjected to solution treatment by heating at a temperature of 545 ° C. and then water quenching. In addition, 18
After aging heat treatment at 0 ° C., it was naturally cooled. Note that T6
Although the treatment is performed, a T4 treatment in which the aging heat treatment at 180 ° C. is not performed may be performed depending on the selected material.

After the surface hardening treatment, the electric conductivity of the obtained cylinder liner is inspected, and the end surface and the inner surface of the cylinder liner are processed to be smooth, and then the outer surface of the cylinder liner is processed, if necessary. Got a liner.

A cylinder liner was attached to the mold of the cylinder block, and cast-molding was performed using an aluminum die casting alloy.

Further, the metallographic structure of the sliding surface formed on the inner peripheral surface of the cylinder liner after the cast-in molding was observed.

FIG. 1 is an enlarged photograph showing the alloy structure of the sliding surface of the cylinder liner of Example 2 made of an Al alloy material containing Fe. As shown in FIG. 1, in the alloy structure, crystallization of Si (1) and the intermetallic compound β-AlFeSi (2) was observed in the matrix. When the alloy structure of the sliding surface was investigated and the deposition area of the intermetallic compound β-AlFeSi per unit area was measured, the area occupied by β-AlFeSi was within the range of 5% or less per unit area. .

Comparative Examples 1 to 4 (Table 1) In this comparative example, since the cylinder liner is formed by the same manufacturing process as that of the above-mentioned embodiment, the description thereof will be omitted. The difference from the examples is that the composition of the Al alloy material is outside the scope of the present invention.

Comparative Examples 1 and 2 are Al alloy materials containing Fe in excess of 2%, and Comparative Examples 3 and 4 are Al alloy materials containing no Fe.

The above Examples 1 to 5 and Comparative Examples 1 to
A cylinder liner made of an Al alloy was formed using each of the Al alloy materials up to Comparative Example 4, and the hardness and wear amount of the cylinder liner (Al alloy itself) were measured. The hardness of the Al alloy forming the cylinder liner was measured by the Rockwell test, and the wear amount was measured by the reciprocating motion wear test.

The reciprocating wear test measures the amount of wear between a polishing wheel and a test piece under a constant load. The test conditions are a load surface pressure of 1.0 N / mm ² and an average test speed of 0. 16
m / s, wear distance was 300 m, 1 ml of lubricating oil was dropped, and the wear volume was measured to obtain the wear amount. The measurement results are shown in FIG.

As shown in FIG. 2, a cylinder liner made of an Al alloy containing 4% by mass of Fe (Comparative Example 1,
The wear amount of Comparative Example 2) was large and the wear resistance was lowered. on the other hand,
The wear amounts of the cylinder liners made of an Al alloy containing no Fe (Comparative Examples 3 and 4) were lower than 0.4, and it was found that the wear resistance was good.

Next, the hardness and wear amount of the matrix in the Al alloy were measured. The hardness of the matrix was measured by a Vickers hardness test, and a Vickers hardness meter with a load of 0.5 g was used. The matrix in the Al alloy is
As shown in FIG. 3, the Vickers hardness of the portion excluding hard particles such as Si was measured, and the average value of 10 measurements was taken as the matrix hardness. The amount of wear was measured under the same test conditions as the above-mentioned reciprocating wear test. Figure 4 shows the measurement results.
Shown in.

As shown in FIG. 4, the Al alloys of Comparative Examples 1 and 2 containing Fe have a matrix hardness of 70.
The value was HV or less, and the amount of wear was increased. On the other hand, F
In the Al alloy materials of Comparative Example 3 and Comparative Example 4 not containing e, the matrix hardness was lower than 70 HV and the wear amount was 0.3 or more. On the other hand, the matrix hardness of each of the Al alloys of Examples 1 to 5 is 70 HV or more, and the wear amount is 0.3.
Below, a cylinder liner having excellent strength and wear resistance was obtained.

Cylinder liners having excellent strength and wear resistance can be obtained by solid-solution hardening or age hardening of the matrix having a composition within the range of this embodiment and having a matrix hardness of 70 HV or more. It has been found.

Therefore, according to this embodiment, the hardness of the Al alloy matrix forming the cylinder liner is 70 H.
By subjecting the matrix to solution-hardening and age-hardening treatment so as to be V or more, a cylinder liner having excellent strength and wear resistance can be obtained.
Since it is not necessary to plate the inner peripheral surface of the cylinder liner, the manufacturing cost of the cylinder liner can be reduced.

[0046]

As described above, according to the present invention,
By applying the cylinder liner of the present invention to an engine, it is possible to obtain an engine cylinder liner that has excellent high temperature strength and wear resistance, and is lightweight and has reduced manufacturing costs. Furthermore, it is possible to reduce the environmental load, which contributes to the development of industry.

[Brief description of drawings]

FIG. 1 is a diagram showing the structure of an Al alloy of Example 2 in the present embodiment.

FIG. 2 is a diagram showing a relationship between hardness and wear amount of an Al alloy.

FIG. 3 is a view showing an example of a sample taken from the Al alloy structure when measuring the hardness of the Al alloy matrix.

FIG. 4 is a diagram showing a relationship between hardness and wear amount of a matrix in an Al alloy.

FIG. 5 is a schematic view showing a cross section of a conventional cylinder block of a multi-cylinder engine.

FIG. 6 is a manual procedure diagram showing a manufacturing process of a conventional cylinder liner having a cast-in structure.

FIG. 7: “Base alloy” and “Base alloy + 4%”
The figure which compared the hardness of the extruded material (T1) and the after-casting (A) about each alloy of "Fe".

[Explanation of symbols]

1 ... Si, 2 ... β-AlFeSi,

Claims (4)

[Claims] 1. A cylinder liner, which is cast in a cylinder block of an engine and has a sliding surface on which an inner surface of which a piston can slide is formed, wherein the cylinder liner contains Al, Si, and Cu as essential components. A cylinder liner made of an Al alloy containing at least one element of Mn and Sn, wherein the hardness of the matrix component in the Al alloy is 70 HV or more. 2. The Al alloy in mass% is Si: 20.
-30, Cu: 0.05-2.0 as an essential component, and Mn: 0.05-4.0 or Sn: 0.01-
2. The cylinder liner according to claim 1, wherein the cylinder liner contains at least one element of 4.0 and the balance is Al and inevitable impurities. 3. The cylinder liner according to claim 1, wherein the Al alloy further contains 10% or less by mass% of Al ₂ O ₃ having a particle size of 2 μm or less. 4. The mass percentage of the Al alloy is Mg: 0.
1 to 1.5, Ni: 1.0 to 4.0, Cr: 0.3 or less, and Fe: 2% or less, and at least one element is contained. The area occupied by the intermetallic compound β-AlFeSi crystallized on the sliding surface is 5% or less with respect to the total area of the sliding surface, according to any one of claims 1 to 3. Cylinder liner.