JP2002372028A - Crankshaft coated with dlc - Google Patents

Abstract

PROBLEM TO BE SOLVED: To elongate the lifetime by reducing the abrasion of a sliding surface of a crankshaft. SOLUTION: A diamond-shaped carbon film is formed on a surface of the crankshaft slid on a surface of a bearing hole of a mating member, optionally through an intermediate layer composed of (a) silicide or silicon carbide composed mainly of at least one of the group Va metal (V, Nb, Ta), the group IVa metal (Cr, Mo, W), Ti and Zr, (b) a metallic film composed mainly of at least one kind of the group Va metal (V, Nb, Ta), and a Si film or a metallic film composed mainly of Si, formed on the metallic film, or (c) a metallic film of at least one kind of the group Va metal (V, Nb, Ta), the group VIa metal (Cr, Mo, W), Ti and Zr, and a silicon carbide film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crankshaft used in a power transmission system for converting a driving force of a reciprocating motion of a piston in a piston / cylinder into a rotary motion in an internal combustion engine of an automobile or the like, and more particularly to a crankshaft. And a crankshaft provided with a wear-resistant coating film on a sliding surface of the crankshaft.

[0002]

2. Description of the Related Art In an internal combustion engine such as an automobile engine,
When an explosive load is applied to a piston that can reciprocate in the cylinder of the combustion chamber, the piston reciprocates, and the movement of the connecting rod connected to the piston via the piston pin at the small end is larger than that of the connecting rod. It is converted into rotational movement of the crankshaft via an eccentric shaft fitted on the end bearing and then transmitted to the wheels via a clutch and a transmission gear. Further, the crankshaft drives a fuel valve and an exhaust valve through a valve mechanism. During the explosion stroke of the internal combustion engine, the cylinder block is vibrated through the bearing hole of the crankshaft, and the internal combustion engine vibrates, and further, a load is applied to the crankshaft. Such vibrations are often accompanied by published resonances, and the resulting wear loss affects the fuel economy of the entire engine and also affects the durability of the engine. Furthermore, since a large torque and a load stress such as torsional vibration are applied to the crankshaft to increase the internal moment, a weight or the like for canceling the moment is added. Therefore, the weight is often severely restricted. In addition, since the surface of the eccentric shaft that slides on the bearing surface of the connecting rod requires high lubricity, it is necessary to strictly control the amount of oil and the like.

FIG. 1 shows some examples of a power transmission system including a crankshaft for driving a wheel, rotating a wheel, and opening and closing a fuel valve. 1 shows an example of a mechanism for transmitting power to wheels and a valve operating mechanism. In FIG. 1, a piston pin 11 is fixed to a piston 5 which reciprocates in a cylinder 3 of an engine 1, and a connecting rod 7
Is pivotally fitted in a bearing hole formed in the small end portion 9. A bearing hole is formed in the large end 13 of the connecting rod 7, and the eccentric shaft 15 of the crankshaft 18 is slidably fitted therein. The reciprocating motion of the connecting rod 7 rotates the crankshaft 18 to transmit power to wheels and other necessary parts. A crankshaft 18 driven via a connecting rod 7 transmitting an engine output via an eccentric shaft 15 drives a cam gear 19 via a crank gear 17, and the cam gear 19 rotates a cam 21. The cam 21 rotates while sliding on the shim 23 on the lower surface of the tappet 25. Thus, the reciprocating tappet 25 opens and closes the fuel valve 29 in synchronization with the operation of the engine, and injects fuel into the cylinder 3. At the small end 9 of the connecting rod 7, the piston pin 11 and the bearing hole for receiving the same, and at the large end 13 eccentric shaft 15 of the crankshaft and the bearing hole for receiving the same, besides the roller or ball bearing, It is known that a bearing hole slides on an eccentric shaft. The latter type is particularly problematic for wear. The present invention relates to a crankshaft of sliding contact type.

[0004]

The wear resistance of the conventional crankshaft is not sufficient and cannot withstand long-term use. Therefore, the sliding contact surface of the crankshaft with the bearing hole needs to have sufficient low friction and wear resistance. In order to reduce the wear on the sliding surface, it is necessary to precisely grind the sliding surface of the crankshaft or the surface of the bearing hole in which it slides, but the grinding process is time-consuming, time-consuming, and increases the cost. There is a problem that sufficient abrasion resistance cannot be obtained. SUMMARY OF THE INVENTION An object of the present invention is to provide a crankshaft having a highly wear-resistant sliding portion without the need for precision polishing of a sliding surface.

[0005]

SUMMARY OF THE INVENTION The present invention provides a crankshaft with reduced abrasion resistance and high wear and durability. More specifically, a crankshaft having the following configuration is provided. (1) A crankshaft which slides in a bearing hole, wherein a diamond-like carbon film is formed on a surface of the crankshaft which slides in the bearing hole. (2) In the above (1), the diamond-like carbon film is composed of carbon and hydrogen, and when its composition is represented by a molar ratio of CHn, the diamond-like carbon film represented by 0.05 ≦ n ≦ 0.7 It contains a film or silicon, and may contain oxygen, nitrogen, and fluorine.
When represented by xSiyOzNvFw, a diamond represented by the following formula: 0.05 ≦ x ≦ 0.7 0.01 ≦ y ≦ 3.0 0 ≦ z ≦ 1.00 0 ≦ v ≦ 1.0 0 ≦ w ≦ 0.2 It consists of at least one layer of a carbon-like film. (3) More preferably, in the above (1), the diamond-like carbon film is formed of CHxSiyOzNvFw (provided that 0.05 ≦ x ≦ 0.7 0.01 ≦ y ≦ 3.0 0 ≦ z ≦ 1.00 ≦) At least two layers of a diamond-like carbon film represented by v ≦ 1.00 ≦ w ≦ 0.2) and a diamond-like carbon film represented by CHn (where 0.05 ≦ n ≦ 0.7) are formed. Or a layer that continuously changes from one of these compositions to the other. (4) More preferably, in the above (1) to (3),
(A) at least one selected from group 5A metals (V, Nb, Ta), group 6A metals (Cr, Mo, W), Ti, and Zr between the crankshaft and the diamond-like carbon film; (B) a metal film mainly containing at least one selected from Group 5A metals (V, Nb, Ta) and a Si film or Si formed thereon; A metal film as a main component, or (c) at least one metal film selected from a group 5A metal (V, Nb, Ta), a group 6A metal (Cr, Mo, W), Ti, and Zr; An intermediate layer comprising a silicon carbide film formed thereon is formed.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive studies, the present inventors have found that a sliding surface of a crankshaft with a bearing hole is coated with a diamond-like carbon film, and in particular, the material of the diamond-like thin film to be coated is appropriately selected. And / or by using an appropriate intermediate layer, the adhesion was improved, and the abrasion resistance was significantly improved. When the crankshaft having the configuration of the present invention is employed, the surface of the bearing hole fitted into the crankshaft does not need to be precisely polished, and has sufficient wear resistance even with a surface roughness of more than 0.1 μm. In addition, when the same structure is adopted on the surface of the base metal or alloy of the bearing as the mating material, the wear resistance is further improved.

In the present invention, a sufficient effect can be obtained only by forming a diamond-like carbon film directly on the surface of the crankshaft. However, in order to enhance the adhesion to the substrate, a diamond-like carbon film containing H and Si is used. If the carbon film is formed, the wear resistance can be further improved. In this case, a diamond-like carbon film containing H can be further formed on the diamond-like carbon film containing H and Si, and further improvement in wear resistance can be expected. More preferably, an intermediate layer is provided between the crankshaft and the diamond-like carbon film. Thereby, the adhesion to the base material is further increased, and the wear resistance can be significantly improved. That is, a diamond-like carbon film is formed on at least a surface of the crankshaft that slides with the bearing hole, or (a) a Group 5A metal (V, Nb,
Ta), a silicide or silicide containing at least one selected from Group 6A metals (Cr, Mo, W), Ti and Zr; (b) a Group 5A metal (V, Nb,
Ta) a metal film mainly composed of at least one selected from Ta) and a Si film or a metal film mainly composed of Si formed thereon, or (c) a Group 5A metal (V, Nb, T
a) an intermediate layer comprising at least one metal film selected from Group 6A metals (Cr, Mo, W), Ti, and Zr and a silicon carbide film formed thereon; Further, if a similar diamond-like carbon film is similarly formed on the surface of the bearing hole of the connecting rod in contact with the crankshaft with or without an intermediate layer, wear resistance is further increased.

In the present invention, any material conventionally used in the art can be used as a base material having a sliding portion, particularly an eccentric shaft portion of a crankshaft, and a bearing hole which fits and slides in the crankshaft. it can. These materials include, for example, various types of carbon steel and cast iron (gray cast iron, spheroidal graphite cast iron, malleable cast iron, alloy cast iron, etc.), cast steel and the like.
CR420, H11 etc.), high speed tool steel (high speed steel:
JIS standard SKH type), alloy tool steel (die steel: SK)
D6), maraging steel (KMS180-20, etc.), ausform steel, stainless steel (SUS30
4, SUS430, 17-4PH, etc.), bearing steel (SU
J2), an Al alloy (eg, AC4C), a Ti alloy, and the like.

[0009] A metal whose hardness is improved by quenching the base metal under appropriate conditions may be used. For quenching, for example, induction hardening, flame quenching, carburizing quenching and the like can be used. Further, a surface hardening treatment may be performed on these substrates or on the quenched substrate, and a diamond-like carbon film or a diamond-like carbon film may be coated thereon with an intermediate layer interposed therebetween. Examples of the surface hardening include nitriding, carburizing, and boring.

Intermediate Layer Next, the intermediate layer used in the present invention comprises (a) a Group 5A metal (V, Nb, Ta) and a Group 6A metal (Cr, Mo,
W) a silicide or silicide containing at least one selected from Ti and Zr as a main component; and (b) a metal containing at least one selected from Group 5A metals (V, Nb, Ta) as a main component. A film and a Si film formed thereon or a metal film containing Si as a main component, or (c) a Group 5A metal (V, Nb, Ta) or a Group 6A metal (Cr, Mo,
W), at least one metal film selected from Ti and Zr, and a silicon carbide film formed thereon.
178736, 2000-178737, 2000
177,046, 2000-178,738, 200
0-90842 and the like.

In the case of the intermediate layer (a), the composition is M
SiaCb (where M is V, Nb, Ta, Cr, M
o, W, at least one of Ti and Zr), 0.3 ≦ a ≦ 10, preferably 1 ≦ a ≦
6, 0 ≦ b ≦ 5, preferably 0 ≦ b ≦ 3, 0.3 ≦ a +
b ≦ 10, preferably 1 ≦ a + b ≦ 6. If a is larger than this and the amount of silicon increases, the adhesion to the base material deteriorates. If a is smaller and silicon is less, then DL
The adhesion to the C film becomes poor. When b is larger than this and the amount of carbon is large, the adhesion to the base material is deteriorated. When b is smaller than this and carbon is reduced, the adhesion to the DLC film is deteriorated. Further, even if a + b is larger than this, the adhesion to the base material is deteriorated.
Adhesion to the film is poor.

The thickness of the intermediate layer is preferably 2 nm to 5 μm, and more preferably 5 nm to 1 μm. With such a thickness, the adhesion is improved. On the other hand, if the intermediate layer is too thin, the effect of improving the adhesion will not be sufficient, and if it is too thick, the impact resistance will deteriorate.

The intermediate layer of the present invention can be formed by a PVD method such as a vacuum evaporation method, a sputtering method, an ion plating method, or a thermal CVD method.
It can be formed by a CVD method such as a plasma CVD method, a photo CVD method, or the like. Wet plating, thermal spraying,
It may be formed by clad bonding or the like. Specifically, a known method is used. In particular, the intermediate layer of the present invention is preferably formed by a sputtering method. In this case, using a target corresponding to the target composition, high-frequency power, AC power, or any of DC power is added, the target is sputtered,
This is sputter deposited on a base material (substrate) to form an intermediate layer.

Usually, the target may have the same composition as that of the intermediate layer. However, the target may be a multi-source sputtering targeting a metal such as Ta and Si, or a case where C or Si is introduced by reactive sputtering. The target which does not contain the component can be used.

As the sputtering gas, an inert gas used in a usual sputtering apparatus can be used. Above all, Ar, K
r or Xe, or at least one of these
It is preferable to use a mixed gas containing at least one kind of gas.
Reactive sputtering may be performed. When carbon is introduced as a reactive gas, CH ₄ , C ₂ H ₂ , C ₂ H
_{4. When} introducing silicon using CO or the like, silane gas or the like is used. When hydrogen is introduced, H ₂ or the like is used. These reactive gases may be used alone or as a mixture of two or more. The operating pressure during sputtering is preferably in the range of 0.2 to 70 Pa. Further, by changing the pressure of the sputtering gas within the above range during the film formation, an intermediate layer having a concentration gradient can be easily obtained.

As the sputtering method, a high frequency sputtering method using an RF power source or a DC sputtering method may be used. The power of the sputtering apparatus is about 0.5 to 30 W / cm ^{2 for} DC sputtering, 1 to 50 MHz for high frequency sputtering, and 50 kHz to 1 MHz for low frequency.
It is preferably about 0.5 to 30 W / cm ² . The deposition rate is 1
The range of -300 nm / min is preferable. Further, the substrate temperature is preferably 10 to 150 ° C.

The intermediate layer of the present invention is formed by a vapor deposition method.
May be. As the evaporation method, even if it is a resistance heating method
An electron beam heating system may be used. The evaporation source is Ta
Even if it is a binary deposition using a metal such as
One-source vapor deposition using the same composition as described above may be used. 1
In the original deposition, the film composition is almost the same as the composition of the deposition source.
Obtained stably occasionally. Conditions for vacuum deposition are particularly limited
No, but the degree of vacuum is 10^-3Pa or less, especially 10 ^-4P
a or less is preferable. The deposition rate is usually 1 to 300 nm
/ Min is preferable.

The intermediate layer can also be formed by a plasma CVD method or an ionization vapor deposition method.
The film may be formed with reference to the LC film.

Diamond-like carbon film A diamond-like carbon (DLC) film is sometimes called a diamond-like carbon film, an i-carbon film, or the like. The diamond-like carbon film is disclosed in, for example, JP-A-62-14.
Nos. 5646 and 62-145647, New Di
amond Forum, Vol. 4, No. 4, issued on October 25, 1988, and the like.

The DLC film is described in the above-mentioned reference (New Diamond Foru).
As described in m), Raman spectroscopy shows a broad (1520 to 1560) at 1550 cm ^−1.
cm ^-1) has a peak of the Raman absorption, and diamond having a sharp peak at 1333 cm ^-1, and graphite having a sharp peak at 1581 cm ^-1, it is a substance having a distinctly different structure. The absorption peak in the Raman spectroscopic analysis of the DLC film has a broad absorption (1520 to 1560 cm ⁻¹ ) at 1550 cm ⁻¹ as described above, but is ± 100 cm ⁻ by containing the above elements other than carbon and hydrogen. ^It may fluctuate by about one.
The DLC film is an amorphous thin film containing carbon and hydrogen as main components, and is formed by randomly existing sp3 bonds between carbon atoms. DLC film is C
Expressed as Hn, the molar ratio is 0.05 ≦ n ≦ 0.7.

In the present invention, the thickness of the DLC film is usually 1 to 10000 nm, preferably 10 nm to 3 μm.
It is.

The DLC film is made of Si, in addition to carbon and hydrogen.
And one or more of O, N, and F may be contained. When the intermediate layer is not used, at least the first layer is made of Si in addition to hydrogen in order to improve the adhesion to the substrate.
Should be contained. In this case, the DLC film is CHxS
When expressed as iyOzNvFw, x, y, z, v, and w are respectively 0.05 ≦ x ≦ 0.7, 0.01 ≦ y ≦ 3.
0, 0 ≦ z ≦ 1.0, 0 ≦ v ≦ 1.0, 0 ≦ w ≦ 0.2
It is preferable that Also, a plurality of layers may be formed, but instead, the composition may be continuously variable in the thickness direction from a portion containing Si to a portion not containing Si.

The DLC film can be formed by a plasma CVD method, an ionization evaporation method, a sputtering method, or the like. DL
When the C film is formed by a plasma CVD method, the C film can be formed by a method described in, for example, JP-A-4-41672. Plasma in the plasma CVD method may be either direct current or alternating current, but it is preferable to use alternating current. The alternating current can be used from a few hertz to a microwave. In addition, E described in diamond thin film technology (published by Comprehensive Technology Center), etc.
CR plasma can also be used. Further, a bias voltage may be applied.

When the DLC film is formed by the plasma CVD method, it is preferable to use the following compound as a raw material gas. Methane, as a compound containing C and H,
Hydrocarbons such as ethane, propane, butane, pentane, hexane, ethylene, propylene and the like can be mentioned. Compounds containing C, H and Si include methylsilane, dimethylsilane, trimethylsilane, tetramethylsilane, diethylsilane, tetraethylsilane, tetrabutylsilane, dimethyldiethylsilane, tetraphenylsilane,
Examples include methyltriphenylsilane, dimethyldiphenylsilane, trimethylphenylsilane, trimethylsilyl-trimethylsilane, and trimethylsilylmethyl-trimethylsilane. These may be used in combination, or a silane compound and a hydrocarbon may be used. Compounds containing C + H + O include CH ₃ OH, C ₂ H ₅ OH, HCHO, CH ₃
COCH _{3 and the} like. Examples of the compound containing C + H + N include ammonium cyanide, hydrogen cyanide, monomethylamine, dimethylamine, allylamine, aniline, diethylamine, acetonitrile, azoisobutane, diallylamine, ethylazide, MMH, DMH, triallylamine, trimethylamine, triethylamine, triphenylamine and the like. is there. In addition, Si + C + H, Si
A compound containing + C + H + O or Si + C + H + N may be combined with an O source or an ON source, an N source, an H source, or the like.

O source, O ₂ , O _3, etc .; C + O source, CO, CO _2, etc .; Si + H source, SiH _4, etc.
As a source, H ₂ or the like, H + O source, H ₂ O, etc., N source, N ₂ N + H source, NH ₃ or the like, N + O source, N
Compounds of N and O, such as O, NO ₂ and N ₂ O, which can be represented by NOx, such as (CN) 2 as an N + C source, NH ₄ F as an N + H + F source, and OF ₂ and O ₂ F ₂ as an O + F source. , O
₃ F ₂ or the like may be used.

The flow rate of the raw material gas may be appropriately determined according to the type of the raw material gas. The operating pressure is typically between 1 and 70
Pa and the input power are usually preferably about 10 W to 5 kW.

The DLC film may be formed by an ionization vapor deposition method. The ionization deposition method is described in, for example, Japanese Patent Application Laid-Open No. 58-17 / 1983.
No. 4507, JP-A-59-174508 and the like. However, the present invention is not limited to the methods and apparatuses disclosed therein, and another type of ion vapor deposition technology may be used as long as the ionized gas for the raw material can be accelerated. As a preferable example of the device in this case, for example, an ion straight type or an ion deflection type described in Japanese Utility Model Laid-Open No. 59-174507 can be used.

In the ionization vapor deposition method, the inside of the vacuum vessel is set to a high vacuum of about 10 ⁻⁴ Pa. A filament that is heated by an AC power supply and generates thermoelectrons is provided in the vacuum vessel. A counter electrode is arranged around the filament, and a voltage Vd is applied between the filament and the filament. In addition, an electromagnetic coil that surrounds the filament and the counter electrode and generates a magnetic field for trapping ionized gas is arranged. The source gas collides with the thermoelectrons from the filament to generate positive thermal decomposition ions and electrons, and the positive ions are accelerated by the negative potential Va applied to the grid. The composition and film quality can be changed by adjusting Vd, Va and the magnetic field of the coil. Further, a bias voltage may be applied.

When the DLC film is formed by the ionization deposition method, the same material gas as in the plasma CVD method may be used. The flow rate of the source gas may be appropriately determined according to the type. The operating pressure is usually 1 to 70 Pa
The degree is preferred.

The DLC film can be formed by a sputtering method. In this case, a gas such as O ₂ , N ₂ , NH ₃ , CH ₄ , H ₂ or the like is introduced as a reactive gas in addition to a sputtering gas for sputtering such as Ar or Kr, and C, Si,
Targeting SiO ₂ , Si ₃ N ₄ , SiC, etc.
A target may be a mixed composition of C, Si, SiO ₂ , Si ₃ N ₄ , and SiC, and in some cases, C, Si, N, O
May be used. Further, a polymer can be used as a target. A DLC film is formed by applying any one of high-frequency power, AC power, and DC power using such a target, sputtering the target, and sputter depositing the target on a substrate. The high frequency sputtering power is usually 50 W to 2 k
It is about W. Operating pressure is usually 10 ^{-3 to} 0.1P
a is preferred.

[0031]

Next, embodiments of the present invention will be described. In the combinations shown in Table 1, the intermediate layer and the DLC film were formed on the surface of the eccentric shaft of the crankshaft and the surface of the bearing hole that slidably engaged therewith. SNCM420 was used as the material of the crankshaft and the bearing-side member fitted thereto.
The surface roughness of all the substrates of the examples was Ra = 0.1 μm. These substrates were placed at predetermined positions in a vacuum chamber, evacuated, and then formed into a film under the following conditions.

<Deposition of Intermediate Layer> The intermediate layer 1 shown in Table 1 was produced by sputtering under the following conditions. Gas used: Ar (5.1 × 10 ⁻² Pa · m ³ ·
s ^-1 ) = 30 sccm Sputtering pressure: 40 Pa Input power: 500 W Target: Ta, Si Film thickness: Ta (first layer) 10 nm, Si (second layer) 9
0 nm

The intermediate layer shown in Table 1 was formed under the same film forming conditions while changing the target. When a single intermediate layer was used, the film thickness was all 100 nm.

[0034]

[Table 1]

<DLC Film Formation> A DLC film was formed by a self-biased RF plasma CVD method under the following conditions. DLC1 raw material gas: C ₂ H ₄ (0.017 Pa · m ³ · s ⁻¹ ) Power supply: RF Operating pressure: 66.5 Pa Input power: 500 W Film formation rate: 100 nm / min Film composition: CH _0.21 Film thickness: 2 μm DLC2 source gas: Si (OCH ₃ ) ₄ (0.085 Pa · m ³
・ S ^-1 ) Power supply: RF Operating pressure: 66.5 Pa Input power: 500 W Film formation rate: 100 nm / min Film composition: CH _0.2 Si _0.1 O _0.17 Film thickness: 2 μm DLC3 raw material gas: Si ( CH ₃ ) ₄ (0.085 Pa · m ³ ·
s ^-1 ) Power supply: RF Operating pressure: 66.5 Pa Input power: 500 W Film formation rate: 100 nm / min Film composition: CH _0.24 Si _0.22 Film thickness: 2 μm

<Evaluation method> A crankshaft without DLC coating (Comparative Example), a crankshaft with DLC coating (Example), and a bearing hole
A durability test was performed under the following conditions. Thereafter, the wear states of the crankshaft and the bearing hole were compared. In the test, in an automobile engine, a piston pin was fitted into a bearing hole of a crankshaft, and the engine was driven. This condition corresponds to the number of revolutions (200
It should be noted that this is an accelerated test corresponding to a much harsher F1 level compared to (0-4000 rpm).
The results were as shown in Table 2. However, the test time was terminated at a maximum of 20 hours.

[0037]

[Table 2]

[0038]

The durability time in Table 2 indicates that the operation of the engine is stopped when the time exceeds the stated time. According to the example of the present invention, it can be seen that a crank shaft having extremely high durability compared to the conventional example could be provided. Example 1
As can be seen from FIGS. 21 to 21, in the present invention, excellent durability is obtained even though precision polishing is not performed as in Comparative Example 1, so that it is possible to reduce the number of steps and cost. ADVANTAGE OF THE INVENTION According to this invention, adhesiveness is improved by selecting the material of the diamond-like thin film which coats at least a crankshaft, and / or using an appropriate intermediate | middle layer, and it can improve abrasion resistance remarkably. done.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a power transmission system including a crankshaft to which the present invention can be applied.

[Explanation of symbols]

 Reference Signs List 1 engine 3 cylinder 5 piston 7 connecting rod 9 small end 11 piston pin 13 large end 15 eccentric shaft 17 crank gear 19 cam gear 21 cam 23 shim 25 tappet 29 fuel valve

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasushi Hashimoto 1-13-1 Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation (72) Inventor Yasuhiro Matsuba 1-13-1 Nihonbashi, Chuo-ku, Tokyo Inside DK Corporation (72) Inventor Seiichi Odaka 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Corporation (72) Inventor Izumi Miyauchi 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Corporation F term (reference) 3J033 AA02 AB10 BA15 4K029 BA32 BA34 BA35 CA04 CA06 DC16 4K030 AA06 AA09 BA28 FA01 LA23

Claims (4)

[Claims] 1. A crankshaft, wherein a diamond-like carbon film is formed on a surface of a crankshaft that slides on a surface of a bearing hole of a mating member. 2. The diamond-like carbon film is composed of carbon and hydrogen, and when its composition is represented by a molar ratio of CHn, a diamond-like carbon film represented by 0.05 ≦ n ≦ 0.7, or , Containing silicon, and may contain oxygen, nitrogen, and fluorine.
When represented by xSiyOzNvFw, a diamond represented by the following formula: 0.05 ≦ x ≦ 0.7 0.01 ≦ y ≦ 3.0 0 ≦ z ≦ 1.00 0 ≦ v ≦ 1.0 0 ≦ w ≦ 0.2 The crankshaft according to claim 1, comprising at least one layer of a carbon-like film. 3. The method according to claim 2, wherein the diamond-like carbon film is made of CHxS.
diamond-like carbon represented by iyOzNvFw (provided that 0.05 ≦ x ≦ 0.7 0.01 ≦ y ≦ 3.0 0 ≦ z ≦ 1.00 ≦ v ≦ 1.00 ≦ w ≦ 0.2) Forming at least two layers of a film and a diamond-like carbon film represented by CHn (where 0.05 ≦ n ≦ 0.7), or continuously changing from one of these compositions to the other The crankshaft according to claim 1, wherein a layer is formed. 4. A method according to claim 1, wherein (a) a Group 5A metal (V, N) is provided between the surface of the crankshaft and the diamond-like carbon film.
b, Ta), Group 6A metals (Cr, Mo, W), Ti,
Or a silicide or silicide containing at least one selected from Zr and (b) a Group 5A metal (V, N
b, Ta) and a metal film mainly composed of at least one selected from the group consisting of Si and a metal film mainly composed of Si, or (c) a Group 5A metal (V, N
b, Ta), Group 6A metals (Cr, Mo, W), Ti,
4. A crankshaft according to claim 1, wherein an intermediate layer comprising at least one metal film selected from Zr and Zr and a silicon carbide film formed thereon is formed.