JP3555513B2 - Internal combustion engine cylinder - Google Patents

Description

【００３９】
次に、各試験片を常温の２０ｗｔ％硫酸中に浸漬して腐食試験を行い、時間毎の重量変化（減少）を測定した。その測定結果を図１に示す。ここで、図中の横軸は腐食時間（ｈｒ）を、縦軸は腐食試験前の各試験片の重量を１００％とした時の相対重量（％）を示している。
【００４０】
図１に示すように、実施例１〜３の場合、Ｎｉ含有量が３．０ｗｔ％であるため、基地組織は、パーライト組織中にオーステナイト組織が分散した状態である。ここで、実施例１のＣｕ含有量（１．０ｗｔ％）は、実施例２，３のＣｕ含有量（０．５ｗｔ％）と比べて多いため、実施例１の耐食性は、実施例２，３よりも若干劣る。また、実施例３のＣｒ含有量（０．５ｗｔ％）は、実施例２のＣｒ含有量（１．５ｗｔ％）と比べて少ないため、実施例３の耐食性は、実施例２よりも若干劣る。すなわち、実施例２、実施例３、実施例１の順に耐食性が良好となっている。しかし、実施例２よりも耐食性が劣る実施例１，３においても、腐食試験開始から７０時間までの耐食性は、比較例２のターカロイと略同等であり、特に試験開始から７０時間以降における腐食性は現行シリンダライナ材料よりも優れている。
【００４１】
実施例４，５の場合、Ｎｉ含有量が１４．０ｗｔ％であるため、基地組織がオーステナイト組織となっており、腐食試験における重量変化は殆どなく、９０時間経過以後であっても優れた耐食性を示していた。
【００４２】
これに対して、比較例１の場合、各成分の含有量が規定範囲よりも少ないため、炭化物生成量が少なく、各例中で最も耐食性が低かった。特に試験開始から７０時間以降における腐食進行が激しい。
【００４３】
また、比較例２の場合、基地組織全面がパーライト組織であるため、腐食試験において希硫酸と激しく反応しており、耐食性は低い。特に、腐食試験開始後すぐの腐食進行が激しい。
【００４４】
【発明の効果】
以上要するに本発明によれば、シリンダボア部を構成する材料の化学組成を規定することで、酸に対する耐食性が良好で、安価で、機械加工性が良好な内燃機関のシリンダを得ることができるという優れた効果を発揮する。
【図面の簡単な説明】
【図１】実施例における腐食試験の腐食時間と重量変化との関係を示す図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a cylinder of an internal combustion engine, and particularly to a cylinder of a diesel engine.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a cylinder of an internal combustion engine, a cylinder liner is provided in a cylinder bore portion or a thermal spray coating is formed in order to improve wear resistance and corrosion resistance.
[0003]
As the cast iron for the cylinder liner, various cast iron materials (for example, tarcaloy) are used in which a small amount of alloy (B, Mo, etc.) is added to gray cast iron as a base material to improve wear resistance.
[0004]
In a diesel engine, combustion produces sulfuric acid from sulfur contained in light oil. Since the turcaloy, which is cited as a conventional cast iron for cylinder liners, is based on gray cast iron, its corrosion resistance to acids (particularly sulfuric acid) is not so good, causing corrosive wear of the liner and deteriorating the LOC (Lubricating Oil Consumption). Such a problem is caused.
[0005]
Therefore, in order to improve the corrosion resistance of cast iron, cast iron obtained by adding P, Cr, Ni, Cu, etc. to a base material to austenite the base structure (hereinafter referred to as austenitic cast iron) is disclosed in Japanese Patent Publication No. 4-68373. Have been. At this time, the compounding amount of Ni in the austenitic cast iron is preferably 13 to 20 wt%, and the compounding amount of Cu is preferably 4.0 to 8.0 wt%.
[0006]
[Problems to be solved by the invention]
However, in the above-described austenitic cast iron, if the content of Ni is large, not only does the production cost rise, but also the machinability of the cast made of austenitic cast iron deteriorates. In particular, in the case of a cylinder liner, if the machinability is poor, it is difficult to form the inner peripheral surface of the liner into a perfect circle, the amount of blow-by gas increases, or the friction with the piston becomes excessive, causing problems such as burning. .
[0007]
For this reason, it is desirable that the amount of Ni is as small as possible. However, if the amount of Ni is less than the above range, the austenite structure becomes unstable, and a sufficient corrosion resistance effect cannot be obtained.
[0008]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a cylinder liner material or a sprayed material which has good corrosion resistance to acid, is inexpensive, and has good machinability, and a cylinder of an internal combustion engine using the same.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the invention according to claim 1 is characterized in that the chemical composition of the cylinder bore portion is
C: 2.5-3.9 wt%,
Si: 1.5 to 2.6 wt%,
Ni: 3.0 to 14.0 wt%,
Cr: 0.5 to 2.5 wt%,
Cu: 0.5-8.0 wt%,
V: 0.5-1.0 wt%,
B: 0.05 to 0.10 wt%,
A cylinder liner for an internal combustion engine, the balance being substantially Fe.
[0010]
According to a second aspect of the present invention, in a cylinder of an internal combustion engine in which a cylinder bore portion is formed of a cylinder liner, the cylinder liner has a chemical composition
C: 2.5-3.9 wt%,
Si: 1.5 to 2.6 wt%,
Ni: 3.0 to 14.0 wt%,
Cr: 0.5 to 2.5 wt%,
Cu: 0.5-8.0 wt%,
V: 0.5-1.0 wt%,
B: 0.05 to 0.10 wt%,
A cylinder for an internal combustion engine cast and formed of a cylinder liner material having the balance substantially Fe.
[0011]
The invention according to claim 3 is a cylinder of an internal combustion engine in which a thermal spray coating is formed on a cylinder bore surface, wherein the thermal spray coating has a chemical composition of:
C: 2.5-3.9 wt%,
Si: 1.5 to 2.6 wt%,
Ni: 3.0 to 14.0 wt%,
Cr: 0.5 to 2.5 wt%,
Cu: 0.5-8.0 wt%,
V: 0.5-1.0 wt%,
B: 0.05 to 0.10 wt%,
A cylinder of an internal combustion engine spray-formed with a spray material whose balance is substantially Fe.
[0012]
According to the cylinder of such an internal combustion engine, the production cost is low and the corrosion resistance is reduced by adding the corrosion resistance improving elements of Cr, Cu, V and B in a predetermined range together with Ni for improving the base structure to an austenitic structure. , Abrasion resistance and machinability are well balanced.
[0013]
The reason for limiting to the above chemical composition will be described below.
[0014]
C is an element necessary for crystallization of graphite and for carbide formation. If the content is less than 2.5% by weight, the amount of carbide generated is reduced, and the wear resistance and corrosion resistance are reduced. On the other hand, if the content is more than 3.9% by weight, the material becomes too hard and the machinability deteriorates.
[0015]
The content of Si is in the same range as that of general austenitic cast iron, and the reason for limiting the range is based on well-known reasons, and therefore, the description is omitted.
[0016]
Ni is an element effective to make the matrix an austenitic structure. If the content is less than 3.0 wt%, an austenite structure is not formed, and the corrosion resistance is reduced. On the other hand, when the content is more than 14.0 wt%, the production cost increases and the machinability deteriorates.
[0017]
Cr is a carbide-forming element and is an effective element for improving wear resistance. If the content is less than 0.5% by weight, the amount of carbide generated is reduced, and the wear resistance and corrosion resistance are reduced. On the other hand, if the content is more than 2.5% by weight, it becomes too hard and the machinability deteriorates.
[0018]
Cu is a weak graphitization-promoting element, and is an element effective for improving corrosion resistance not only to a mineral acid such as dilute sulfuric acid but also to the atmosphere, especially to an atmosphere containing sulfur. improves. If the content is less than 0.5% by weight, the pearlite structure is not refined and the ferrite structure is increased, resulting in reduced wear resistance and corrosion resistance. If the content is more than 8.0 wt%, castability and machinability deteriorate.
[0019]
V is a strong carbide-forming element, and when added in a small amount, improves the graphite structure and refines pearlite to improve mechanical properties. The reason for limiting the content is the same as in the case of Cr.
[0020]
B is an element that inhibits graphitization and increases the strength of cast iron, and is an element effective in improving corrosion resistance not only to a mineral acid such as dilute sulfuric acid but also to the atmosphere, particularly an atmosphere containing sulfur. The mechanical properties are improved by the combined addition. The reason for limiting the content is the same as in the case of Cr.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described.
[0022]
The cylinder of the internal combustion engine of the present invention, the cylinder bore portion is formed by a cylinder liner, the cylinder liner, the chemical composition,
C: 2.5-3.9 wt%,
Si: 1.5 to 2.6 wt%,
Ni: 3.0 to 14.0 wt%,
Cr: 0.5 to 2.5 wt%,
Cu: 0.5-8.0 wt%,
V: 0.5-1.0 wt%,
B: 0.05 to 0.10 wt%,
The balance is made of a cylinder liner material substantially composed of Fe.
[0023]
By including Ni in the range of 3.0 to 14.0 wt% in the cylinder liner material, the base structure can be made an austenitic structure having good corrosion resistance. Here, when the Ni content is in the range of 3.0 to 4.0 wt%, the base structure becomes a state in which the austenite structure is dispersed in the pearlite structure. Further, when the Ni content is in the range of 4.0 to 8.0 wt%, the base structure becomes a state in which the austenite structure is dispersed in the martensite structure. Further, when the Ni content is in the range of 12.0 to 14.0 wt%, the entire base structure becomes an austenitic structure as it is cast.
[0024]
In addition, by including various corrosion-resistant elements (Cr, Cu, V, B) in a predetermined range in the cylinder liner material, the synergistic effect of each element causes the corrosion resistance, particularly the corrosion resistance in an atmosphere containing sulfur. Improvement can be achieved. Here, the addition of Cu improves the base strength by making the pearlite structure finer, and also improves the wear resistance and corrosion resistance. However, in the case where the Ni content in the cylinder liner material is small (for example, 3.0 to 8.0 wt%) and the base structure in which the austenite structure is dispersed in the base, the corrosion resistance is reduced if the Cu content is too large. I do. Therefore, the Cu content in this case is preferably as small as possible, and is preferably 0.5 to 1.0 wt%.
[0025]
After pouring the molten cast iron composed of the above components into a mold, cooling is performed at a predetermined cooling rate, and for example, a substantially cylindrical cylinder liner having a wall thickness of about 1.5 to 3 mm is formed.
[0026]
The cylinder liner is inserted (or press-fitted) or cast into a cylinder bore of a cylinder block formed of cast iron or an aluminum alloy, whereby the inner peripheral surface of the cylinder liner has a cylinder bore surface. The engine cylinder can be obtained.
[0027]
Since such a cylinder liner is formed by casting using a cylinder liner material that improves the base structure and the corrosion resistance in an atmosphere containing sulfur, the corrosion resistance to sulfuric acid is improved. Therefore, in the cylinder of the internal combustion engine in which the cylinder liner is provided in the cylinder bore portion, there is no possibility that corrosion and wear will occur and LOC will not deteriorate.
[0028]
Further, since the Ni content of the cylinder liner material is 3.0 to 14.0% by weight and the Ni content is smaller than that of the conventional austenitic cast iron described above, the production cost of the cylinder liner, and hence the production of the cylinder, is increased. Cost is reduced. Further, for the same reason, the machinability of the cylinder liner is improved, so that an increase in the amount of blow-by gas and burning can be prevented.
[0029]
The cylinder liner material constituting the cylinder liner may contain a small amount of S or the like as an unavoidable impurity. However, since S makes the material brittle, the smaller the content, the better, and the content is less than 0.02 wt%. It is desirable to stop.
[0030]
Next, another embodiment of the present invention will be described.
[0031]
The above-described cylinder of the internal combustion engine of the present invention has a cylinder bore provided with a cylinder liner.
[0032]
On the other hand, the cylinder of the internal combustion engine of the present embodiment is made of a sprayed material having the same composition as the above-described cylinder liner material on the inner peripheral surface of the cylinder bore portion of the cylinder block previously formed of cast iron or aluminum alloy. A thermal spray coating was formed.
[0033]
The thickness of the thermal spray coating is appropriately determined depending on the wear resistance and corrosion resistance required for the cylinder, but is preferably 1 mm or less from the viewpoint of reducing the weight of the cylinder block.
[0034]
The method for forming the thermal spray coating is not particularly limited, and includes all general coating methods, such as plasma spraying and gas spraying.
[0035]
Needless to say, the cylinder of the internal combustion engine of the present embodiment also has the same effect as the cylinder of the internal combustion engine of the present invention. Since the thermal spray coating made of the thermal spray material is formed, the corrosion resistance to sulfuric acid is good.
[0036]
Further, since the cylinder is formed by forming a thin sprayed coating having a thickness of 1 mm or less on the inner peripheral surface of the cylinder bore without using a cylinder liner, the internal combustion engine of the present invention in which a cylinder liner having a thickness of about several mm is provided in the cylinder bore. In particular, by applying the present invention to a cylinder block made of an aluminum alloy, the weight can be more effectively reduced.
[0037]
【Example】
(Example)
Each of the cast iron melts having the chemical compositions shown in Table 1 below is produced, and each of the cast iron melts (Examples 1 to 5, Comparative Examples 1 and 2) is poured into a mold at a casting temperature of 1,500 ° C., and then cooled to a predetermined temperature. Cooling is performed at a speed, and a test piece having a width of 10 mm, a thickness of 5 mm, and a length of 50 mm is cast and formed. Here, Comparative Example 2 is a chemical composition of Tarcaloy, which is a current cylinder liner material.
[0038]
[Table 1]

[0039]
Next, each test piece was immersed in 20% by weight sulfuric acid at room temperature to perform a corrosion test, and a weight change (decrease) with time was measured. FIG. 1 shows the measurement results. Here, the horizontal axis in the figure indicates the corrosion time (hr), and the vertical axis indicates the relative weight (%) when the weight of each specimen before the corrosion test is 100%.
[0040]
As shown in FIG. 1, in Examples 1 to 3, the Ni content is 3.0 wt%, and thus the base structure is a state in which the austenite structure is dispersed in the pearlite structure. Here, since the Cu content (1.0 wt%) of Example 1 was larger than the Cu content (0.5 wt%) of Examples 2 and 3, the corrosion resistance of Example 1 was higher than that of Examples 2 and 3. Slightly inferior to 3. Further, since the Cr content (0.5 wt%) of Example 3 was smaller than the Cr content (1.5 wt%) of Example 2, the corrosion resistance of Example 3 was slightly inferior to that of Example 2. . That is, the corrosion resistance was good in the order of Example 2, Example 3, and Example 1. However, even in Examples 1 and 3 which are inferior in corrosion resistance to Example 2, the corrosion resistance up to 70 hours from the start of the corrosion test is almost the same as that of Tarcaloy of Comparative Example 2, especially the corrosion resistance after 70 hours from the start of the test. Is superior to current cylinder liner materials.
[0041]
In Examples 4 and 5, since the Ni content was 14.0 wt%, the base structure was an austenitic structure, there was almost no change in weight in the corrosion test, and excellent corrosion resistance even after 90 hours had elapsed. Was shown.
[0042]
On the other hand, in the case of Comparative Example 1, since the content of each component was smaller than the specified range, the amount of carbide generated was small, and the corrosion resistance was the lowest in each example. In particular, the corrosion progressed rapidly after 70 hours from the start of the test.
[0043]
In the case of Comparative Example 2, since the entire base structure was a pearlite structure, it reacted violently with dilute sulfuric acid in the corrosion test, and the corrosion resistance was low. In particular, the corrosion progresses immediately after the start of the corrosion test.
[0044]
【The invention's effect】
In short, according to the present invention, by defining the chemical composition of the material constituting the cylinder bore portion, it is possible to obtain a cylinder of an internal combustion engine that has good corrosion resistance to acid, is inexpensive, and has good machinability. It exerts its effect.
[Brief description of the drawings]
FIG. 1 is a diagram showing a relationship between a corrosion time in a corrosion test and a change in weight in an example.

Claims (3)

The chemical composition of the cylinder bore is
C: 2.5-3.9 wt%,
Si: 1.5 to 2.6 wt%,
Ni: 3.0 to 14.0 wt%,
Cr: 0.5 to 2.5 wt%,
Cu: 0.5-8.0 wt%,
V: 0.5-1.0 wt%,
B: 0.05 to 0.10 wt%,
A cylinder for an internal combustion engine, the balance being substantially Fe. In a cylinder of an internal combustion engine in which a cylinder bore portion is formed of a cylinder liner, the chemical composition of the cylinder liner is
C: 2.5-3.9 wt%,
Si: 1.5 to 2.6 wt%,
Ni: 3.0 to 14.0 wt%,
Cr: 0.5 to 2.5 wt%,
Cu: 0.5-8.0 wt%,
V: 0.5-1.0 wt%,
B: 0.05 to 0.10 wt%,
A cylinder for an internal combustion engine, wherein the cylinder is formed of a cylinder liner material whose balance is substantially Fe. In a cylinder of an internal combustion engine having a sprayed coating formed on a cylinder bore surface, the sprayed coating has a chemical composition of:
C: 2.5-3.9 wt%,
Si: 1.5 to 2.6 wt%,
Ni: 3.0 to 14.0 wt%,
Cr: 0.5 to 2.5 wt%,
Cu: 0.5-8.0 wt%,
V: 0.5-1.0 wt%,
B: 0.05 to 0.10 wt%,
A cylinder for an internal combustion engine, wherein the remainder is formed by thermal spraying with a thermal spray material of substantially Fe.

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