JP2010084217A - Bearing member for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing member for an internal combustion engine composed of an aluminum alloy having high rigidity, a low thermal expansion coefficient and satisfactory castability. <P>SOLUTION: The bearing material for an internal combustion engine is composed of an aluminum alloy having a composition comprising 15 to 18% Si, 4 to 6% Cu, 1.0 to 3% Fe, 0.5 to 2% Mn, 1.0 to 6% Ni and 0.001 to 0.02% P, and in which the total content of Fe, Mn and Ni is 3.0 to 11 mass%, and the balance Al with inevitable impurities, and in which Si and intermetallic compounds are crystallized out by ≥30 vol.%. The aluminum alloy, if required, includes either or both of 0.1 to 1.0% Cr and 0.01 to 1.0% Ti, and, if required, includes at least one selected from the group consisting of 0.0001 to 1.0% B, 0.1 to 1.0% V, 0.1 to 1.0% Zr, and 0.01 to 1.0% Mo as well. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a bearing member such as a ladder frame or a bearing cap used in an internal combustion engine such as an automobile engine. More specifically, the present invention is made of an aluminum alloy having particularly high rigidity, a low linear expansion coefficient, and good castability. The present invention relates to a bearing member for an internal combustion engine.

Conventionally, cast iron has been used for crankshaft bearings and the like of internal combustion engines such as automobile engines, but aluminum materials are being used in response to demands for weight reduction. However, parts that receive heavy loads, such as crankshaft bearings, require high rigidity, and in order to prevent an increase in clearance with the crankshaft due to temperature rise during engine operation, It is also necessary that the difference between the shaft and the thermal expansion coefficient is small.
For these reasons, for example, Patent Document 1 proposes a ladder frame made of an aluminum alloy in which cast iron is cast in a bearing portion.

Patent Document 2 discloses an aluminum alloy composite material in which alumina (Al ₂ O ₃ ), silicon carbide (SiC), or the like is combined as a reinforcing material in an aluminum alloy as an aluminum alloy having high rigidity. .
JP 60-219436 A Japanese Patent No. 3815658

However, from the viewpoint of energy saving in recent years, there is a further demand for weight reduction of automobiles for improving fuel efficiency. Therefore, in the cast iron cast aluminum crank bearing components described in Patent Document 1, the total weight of the parts is still heavy. Does not meet that requirement.
In addition, the aluminum alloy composite material described in Patent Document 2 has problems such as a complicated manufacturing process and high cost, and a lot of restrictions during recycling because it contains alumina, silicon carbide, or the like. .

  The present invention has been made in view of such problems of the prior art, and an object thereof is an aluminum alloy suitable for manufacturing a bearing member for an internal combustion engine, that is, high rigidity (high Young's modulus). Another object of the present invention is to provide a bearing member for an internal combustion engine made of an aluminum alloy having a low linear expansion coefficient and having good castability that can be cast even for a thick part.

  As a result of intensive studies to achieve the above object, the inventors of the present invention contain Si, Cu, Fe, Mn, Ni, P, etc. in a specific range, and Si and an intermetallic compound are in a certain amount or more. It has been found that the crystallized aluminum alloy has the desired rigidity, linear expansion coefficient, and castability, and the present invention has been completed by using this aluminum alloy for a bearing member for an internal combustion engine.

  That is, the bearing member for an internal combustion engine of the present invention has 15 to 18% by mass of Si, 4 to 6% by mass of Cu, 1.0 to 3% by mass of Fe, 0.5 to 2% by mass of Mn, 1. 0 to 6% by mass of Ni, 0.001 to 0.02% by mass of P, the total amount of Fe, Mn and Ni is 3.0 to 11% by mass with the balance being Al and inevitable impurities And an aluminum alloy in which Si and an intermetallic compound are crystallized at 30 volume% or more.

  Further, the bearing member for an internal combustion engine of the present invention, in addition to the above components, is any of Cr: 0.1 to 1.0% by mass and Ti: 0.01 to 1.0% by mass, as necessary. One or both of them are contained, and if necessary, B: 0.0001 to 1.0 mass%, V: 0.1 to 1.0 mass%, Zr: 0.1 to 1.0 mass%, and Mo : It contains at least 1 sort (s) chosen from the group which consists of 0.01-1.0 mass%.

  According to the present invention, Si, Cu, Fe, Mn, Ni, P, etc. can be obtained by examining the interrelationship between the elemental components constituting the aluminum alloy and the rigidity, linear expansion coefficient, and castability of the aluminum alloy. The aluminum alloy contains a specific range and Si and intermetallic compounds crystallize more than a certain amount. Therefore, it has high rigidity (high Young's modulus), low linear expansion coefficient, and thickness. It is possible to provide a bearing member for an internal combustion engine made of an aluminum alloy having good castability that can be cast even for parts.

  Hereinafter, the bearing member for an internal combustion engine of the present invention will be described in more detail together with the action of each alloy component and the reason for limiting the numerical value thereof. In the present specification, “%” means mass percentage unless otherwise specified.

  The present invention relates to the mutual relationship between the content of elemental components such as Si, Cu, Fe, Mn, Ni, and P in an aluminum alloy and the crystallization amount of Si and intermetallic compounds, and the obtained rigidity, linear expansion coefficient, and castability. This is based on finding the relationship.

  That is, as described above, the bearing member for an internal combustion engine of the present invention has 15-18% Si, 4-6% Cu, 1.0-3% Fe, 0.5-2% Mn, 0.0 to 6% Ni, 0.001 to 0.02% P, the total amount of Fe, Mn and Ni is 3.0 to 11% by mass, the balance being Al and inevitable impurities It is made of an aluminum alloy in which Si and an intermetallic compound are crystallized at 30% by volume or more.

  In addition to the above components, if necessary, it contains either one or both of Cr: 0.1 to 1.0%, Ti: 0.01 to 1.0%, and further if necessary. B: 0.0001-1.0%, V: 0.1-1.0%, Zr: 0.1-1.0% and Mo: 0.01-1.0% And at least one of them.

The aluminum alloy used for the internal combustion engine bearing member of the present invention contains elemental components in the above-described appropriate range, and Si and intermetallic compounds are crystallized at 30% by volume or more. It improves the property.
Si is crystallized as primary crystal Si or eutectic Si. Examples of the intermetallic compound to be crystallized include Al-Fe-Si, Al-Si-Fe-Mn, Al-Cu, Al-Ni-Cu, Al-Fe-Mn, and Al-Ni. And Al—Ni—Fe—Mn, Al—Si—Fe—Mn, and Al—Si—Fe—Mn—Cr compounds. These crystallization amounts affect the rigidity and linear expansion coefficient of the aluminum alloy.

The aluminum alloy has a Young's modulus of preferably 88 GPa or more, and more preferably 90 GPa or more. The low linear expansion coefficient is preferably 18 × 10 ⁻⁶ / ° C. or less.

By setting the Young's modulus to 88 GPa or more, in a bearing member for an internal combustion engine, for example, fluttering of a shaft or deformation of a block due to crank rotation can be suppressed. In addition, by setting the linear expansion coefficient to 18 × 10 ⁻⁶ / ° C. or less, for example, when the temperature rises due to crank operation, the difference between the coefficients of thermal expansion due to the difference in the material of the crank (iron system) and the bearing member It is possible to suppress an increase in the clearance. That is, when the Young's modulus is less than 88 GPa, the block vibration and the main body sound tend to increase, and when the linear expansion coefficient exceeds 18 × 10 ⁻⁶ / ° C., the clearance increases and the crank rotation shaft swings and the crank strikes the bearing. May occur.

Furthermore, in order to ensure the same acoustic and vibration performance as that of a conventional aluminum alloy crank bearing component that casts cast iron, the Young's modulus is 90 GPa or more and the low linear expansion coefficient is 18 × 10 ⁻⁶ / ° C. or less. Good.
The term “good castability” as used herein means that a thick part can be cast by a die casting method (cooling rate of 30 ° C./second or more).

  The reasons for limiting the numerical values will be described below together with the action of each component element of the aluminum alloy used in the present invention.

Si: 15-18%
Si is crystallized as eutectic Si, primary crystal Si, Al—Fe—Si based, Al—Si—Fe—Mn based compound, and has the effect of improving rigidity. Si also has the effect of reducing the low linear expansion coefficient and the effect of improving wear resistance.
These effects become prominent at 15% or more. However, if it exceeds 25%, the primary crystal Si becomes coarse and the rigidity is lowered. Further, the machinability is remarkably deteriorated by coarse Si.
On the other hand, in order to ensure the castability of thick parts such as crank bearing components, it is necessary to make it 18% or less.
Therefore, the Si amount for obtaining high rigidity (high Young's modulus) and a low linear expansion coefficient is 15% or more, and the Si amount for securing castability is 18% or less. In addition, it is preferable to raise casting temperature as the amount of Si increases.

Cu: 4 to 6%
Cu crystallizes out as an Al-Cu-based or Al-Ni-Cu-based compound and contributes to improvement in rigidity. This effect becomes prominent when 4% or more is added. However, if it exceeds 6%, the compound becomes coarse, and the elongation decreases, and the corrosion resistance also decreases. Further, in order to ensure the castability of thick parts such as crank bearing components, it is necessary to make it 6% or less.

Fe: 1.0 to 3%
Mn: 0.5-2%
Ni: 1.0-6%
Fe + Mn + Ni: 3.0 to 11%
Fe, Mn, Ni are Al-Fe-Mn, Al-Fe-Si, Al-Ni, Al-Ni-Cu, Al-Ni-Fe-Mn, Al-Si-Fe-Mn Crystallized as a compound, has the effect of improving rigidity and reducing the coefficient of linear expansion. It also has the effect of improving heat resistance.
These effects become significant when Fe + Mn + Ni is 3.0% or more. However, when it exceeds 11%, the crystallized material becomes coarse, and the effect of improving the rigidity is reduced, and the castability is also deteriorated.

P: 0.001 to 0.02%
P has the effect of making primary crystal Si fine and uniformly dispersing. This effect is significant at 0.001% or more, but if it exceeds 0.02%, the viscosity of the molten metal increases and the castability deteriorates.

Cr: 0.1 to 1.0%
Cr crystallizes out as an Al—Si—Fe—Mn—Cr compound and contributes to the improvement of rigidity. Moreover, it has the effect | action which refines | miniaturizes primary crystal Si and disperse | distributes it uniformly. This effect is remarkable at 0.1% or more, but when it exceeds 1.0%, a coarse compound is formed, and on the contrary, the elongation decreases.

Ti: 0.01 to 1.0%
Ti refines the α phase, contributes to improvement of castability, and has an action of preventing the Al—Ni compound from becoming coarse. The effect becomes significant when Ti is 0.01% or more, but when it exceeds 1.0%, a coarse compound is formed, and the elongation is reduced.

B: 0.0001 to 1.0%
V: 0.1 to 1.0%
Zr: 0.1 to 1.0%
Mo: 0.01 to 1.0%
B, V, Zr, and Mo form a highly rigid crystallized product and contribute to the improvement of rigidity. If any element is added in excess of the upper limit, a coarse crystallized product is formed and elongation is lowered.

〔Production method〕
In the present invention, the aluminum alloy is preferably cast at a cooling rate of 30 ° C./second or more. For example, in order to be used as a bearing member for a high-power engine, it is desirable to have high strength in addition to high rigidity and low linear expansion coefficient. However, according to the above-described casting method, generation of gas porosity (casting defect) This is because the strength of the component can be increased. In addition, Young's modulus is improved by reducing casting defects.
In order to cast at such a high cooling rate, for example, a die casting method (high-speed and high-pressure casting method) such as a high vacuum die casting method, a PF method (non-porous die casting method), a semi-melting / semi-solid die casting method, or the like is used. preferable.

The resulting aluminum alloy casting is subjected to, for example, aging precipitation strengthening to obtain the strength to withstand the heavy load of the crank of a high-power engine, and dimensional stabilization processing to prevent deformation during engine operation, for example, by aging treatment be able to. According to aging precipitation (overaging), the permanent growth of the aluminum alloy can be suppressed, so that the linear expansion coefficient can be further reduced.
The aging treatment is preferably performed at 200 to 280 ° C. for 0.3 to 5.0 hours. If the temperature is shorter than this, sufficient dimensional stability may not be obtained. If the temperature is longer than this, the strength may be reduced due to overaging softening.

  Further, as described above, since casting by the die casting method can significantly reduce the occurrence of gas porosity (casting defects), the occurrence of blisters can be suppressed even in high-temperature heat treatment. Therefore, the obtained aluminum alloy casting can be subjected to an aging treatment at 200 to 280 ° C. for 0.3 to 5.0 hours after, for example, a solution treatment at 450 to 550 ° C. for 1 to 8 hours. By these treatments, the Young's modulus and the linear expansion coefficient can be further improved.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples.

[Manufacture of crank bearings]
The 26 types of aluminum alloys (17 types of Examples and 9 types of Comparative Examples) having the chemical composition and crystallized material volume ratio shown in Table 1 are each shown in FIG. 1 by a high pressure die casting method at a casting temperature of 730 ° C. Cast into a shape of a simple bearing member (ladder frame). Subsequently, it was aged by holding at 200 ° C. for 4 hours to obtain a crank bearing of each example.

[Evaluation]
The crank bearing of each example obtained as described above was measured for rigidity (Young's modulus: E) and linear expansion coefficient (thermal expansion coefficient: α), Young's modulus was 88 GPa or more, and linear expansion coefficient was 18 × 10. Evaluation was made with ⁻⁶ / ° C. or less as a reference value. These reference values were set to values at which acoustic and vibration characteristics equivalent to those of conventional cast iron or cast iron encased aluminum alloy bearings could be obtained.

Further, the castability was judged based on the possibility of die casting. Whether or not die casting can be performed was evaluated as follows: ○: continuous casting is possible, Δ: continuous casting is possible but product cracking may occur, and x: product cracking rate exceeds 50%.
These measurement results and evaluation results are shown in Table 1. In the comparative examples of Table 1, numerical values that do not satisfy the conditions are underlined.

[Discussion]
(1) In Examples 1 to 17, the values of Young's modulus and linear expansion coefficient satisfied the standard values, and the castability was also ◯ or Δ.
(2) In Comparative Example 1, neither the Young's modulus nor the linear expansion coefficient satisfies the standard value. This is presumably because the Si content was reduced because the Si content was insufficient.
(3) In Comparative Example 2, both the Young's modulus and the linear expansion coefficient satisfied the standard values, but the product was cracked. This is because the castability is remarkably deteriorated due to an excessive amount of Si and an increase in the liquidus.
(4) In Comparative Example 3, neither the Young's modulus nor the linear expansion coefficient satisfies the reference value. This is considered to be caused by a decrease in Al-Cu-based and Al-Ni-Cu-based compounds due to insufficient Cu content.
(5) In Comparative Example 4, the Young's modulus and the linear expansion coefficient both satisfied the standard values, but cracks occurred in the product. This is because the castability is remarkably deteriorated due to an excessive amount of Cu and an increase in the liquidus.
(6) In Comparative Examples 5 to 7, the Young's modulus or Young's modulus and the linear expansion coefficient do not satisfy the reference value. This is because the total content of Ni + Fe + Mn is 3.0% by mass or less, Al—Fe—Mn, Al—Fe—Si, Al—Ni, Al—Ni—Cu, Al—Ni—Fe. This is considered to be caused by a decrease in the amount of crystallization of the -Mn-based and Al-Si-Fe-Mn-based compounds.
(7) In Comparative Examples 8 to 9, cracks occurred in the products although Young's modulus and linear expansion coefficient satisfied the standard values. This is because the castability deteriorated remarkably due to a large amount of Fe and Mn and an increase in the liquidus.

  Although the present invention has been described in detail with some embodiments and examples, the present invention is not limited to these embodiments and examples, and various modifications are possible within the scope of the gist of the present invention. is there.

It is the front view and sectional drawing which show the ladder frame which is one Embodiment of the bearing member for internal combustion engines of this invention.

Claims (9)

  Si: 15-18% by mass, Cu: 4-6% by mass, Fe: 1.0-3% by mass, Mn: 0.5-2% by mass, Ni: 1.0-6% by mass, P: 0. 001-0.02 mass%, the total amount of Fe, Mn and Ni is 3.0-11 mass%, the balance is Al and inevitable impurities, and Si and intermetallic compounds are 30 A bearing member for an internal combustion engine comprising an aluminum alloy crystallized by volume% or more.   Si: 15-18% by mass, Cu: 4-6% by mass, Fe: 1.0-3% by mass, Mn: 0.5-2% by mass, Ni: 1.0-6% by mass, P: 0. 001-0.02% by mass, Cr: 0.1-1.0% by mass, the total amount of Fe, Mn and Ni is 3.0-11% by mass, the balance being Al and inevitable impurities And a bearing member for an internal combustion engine, comprising an aluminum alloy in which Si and an intermetallic compound are crystallized by 30% by volume or more.   Si: 15-18% by mass, Cu: 4-6% by mass, Fe: 1.0-3% by mass, Mn: 0.5-2% by mass, Ni: 1.0-6% by mass, P: 0. 001-0.02% by mass, Ti: 0.01-1.0% by mass, the total amount of Fe, Mn and Ni is 3.0-11% by mass, the balance being Al and inevitable impurities And a bearing member for an internal combustion engine, comprising an aluminum alloy in which Si and an intermetallic compound are crystallized by 30% by volume or more.   Si: 15-18% by mass, Cu: 4-6% by mass, Fe: 1.0-3% by mass, Mn: 0.5-2% by mass, Ni: 1.0-6% by mass, P: 0. 001-0.02 mass%, B: 0.0001-1.0 mass%, V: 0.1-1.0 mass%, Zr: 0.1-1.0 mass%, and Mo: 0.01 Containing at least one selected from the group consisting of -1.0 mass%, the total amount of Fe, Mn and Ni is 3.0-11 mass%, the balance being Al and inevitable impurities, A bearing member for an internal combustion engine, comprising an aluminum alloy crystallized by 30% by volume or more of Si and an intermetallic compound.   Si: 15-18% by mass, Cu: 4-6% by mass, Fe: 1.0-3% by mass, Mn: 0.5-2% by mass, Ni: 1.0-6% by mass, P: 0. 001-0.02 mass%, Cr: 0.1-1.0 mass%, B: 0.0001-1.0 mass%, V: 0.1-1.0 mass%, Zr: 0.1 And at least one selected from the group consisting of 0.01 to 1.0% by mass and Mo: 0.01 to 1.0% by mass, and the total amount of Fe, Mn and Ni was 3.0 to 11% by mass. A bearing member for an internal combustion engine, characterized in that the balance is Al and inevitable impurities, and Si and an intermetallic compound are crystallized at 30 volume% or more.   Si: 15-18% by mass, Cu: 4-6% by mass, Fe: 1.0-3% by mass, Mn: 0.5-2% by mass, Ni: 1.0-6% by mass, P: 0. 001-0.02 mass%, Ti: 0.01-1.0 mass%, B: 0.0001-1.0 mass%, V: 0.1-1.0 mass%, Zr: 0.1 And at least one selected from the group consisting of 0.01 to 1.0% by mass and Mo: 0.01 to 1.0% by mass, and the total amount of Fe, Mn and Ni was 3.0 to 11% by mass. A bearing member for an internal combustion engine, characterized in that the balance is Al and inevitable impurities, and Si and an intermetallic compound are crystallized at 30 volume% or more.   Si: 15-18% by mass, Cu: 4-6% by mass, Fe: 1.0-3% by mass, Mn: 0.5-2% by mass, Ni: 1.0-6% by mass, P: 0. 001-0.02 mass%, Cr: 0.1-1.0 mass%, Ti: 0.01-1.0 mass% is contained, and the total amount of Fe, Mn, and Ni is 3.0-11 mass %, The balance being Al and inevitable impurities, and comprising an aluminum alloy crystallized by 30 volume% or more of Si and intermetallic compounds.   Si: 15-18% by mass, Cu: 4-6% by mass, Fe: 1.0-3% by mass, Mn: 0.5-2% by mass, Ni: 1.0-6% by mass, P: 0. 001-0.02 mass%, Cr: 0.1-1.0 mass%, Ti: 0.01-1.0 mass%, B: 0.0001-1.0 mass%, V: 0.1 Containing at least one selected from the group consisting of -1.0% by mass, Zr: 0.1-1.0% by mass and Mo: 0.01-1.0% by mass; Fe, Mn and Ni An internal combustion engine having a total amount of 3.0 to 11% by mass, the balance being Al and inevitable impurities, and an aluminum alloy in which Si and an intermetallic compound are crystallized at 30% by volume or more. Bearing member. 9. The bearing member for an internal combustion engine according to claim 1, wherein the aluminum alloy has a Young's modulus of 88 GPa or more and a low linear expansion coefficient of 18 × 10 ⁻⁶ / ° C. or less.

Images