JP5744000B2 - Sliding component for internal combustion engine, internal combustion engine, transport equipment, and method for manufacturing sliding component for internal combustion engine - Google Patents

Description

  The present invention relates to a sliding component for an internal combustion engine, and more particularly to a sliding component made of titanium or a titanium alloy. The present invention also relates to an internal combustion engine and a transport device provided with such a sliding component, and a method for manufacturing such a sliding component.

  In recent years, titanium alloys have been increasingly used for the purpose of reducing the weight of components for internal combustion engines, in particular, reciprocating components such as connecting rods, lifters, and valves. However, although titanium alloy is lightweight, it has high activity and therefore has low seizure resistance. Further, since the titanium alloy has a lower hardness than steel, the wear resistance is also low. Therefore, a surface hardening process such as an oxidation process, a nitriding process, or a carbonizing process is performed on the titanium alloy component. By forming a surface hardened layer on the surface of the component by the surface hardening treatment, seizure resistance and wear resistance are improved.

  When a titanium alloy part is used as a sliding part that slides in contact with another part, it is preferable that the coefficient of friction on the part surface be as small as possible. Therefore, it has been proposed to form a diamond-like carbon (DLC) film having a low coefficient of friction on the hardened surface layer. For example, Patent Document 1 discloses a technique in which a carbide layer is formed by carburizing a surface of a titanium alloy tappet as a surface hardening treatment, and a DLC film is formed on the carbide layer (surface hardening layer). ing.

JP 2006-257842 A

  However, when the DLC film is formed on the hardened surface layer, the adhesion between the hardened surface layer, which is a ceramic layer such as a carbide layer, an oxide layer, and the DLC film is low. There exists a problem that it is easy to peel and its impact resistance is low.

  Patent Document 1 describes that the adhesion of the DLC film to the carbide layer is improved by removing the oxide film formed on the surface of the carbide layer before the step of forming the DLC film. Yes. However, according to the study of the present inventor, it has been found that sufficiently high adhesion and impact resistance cannot be obtained even by the method described in Patent Document 1.

  The present invention has been made in view of the above problems, and its purpose is to improve the adhesion of a DLC film provided on the surface of a sliding component made of titanium or a titanium alloy, thereby realizing excellent impact resistance. There is.

  A sliding component for an internal combustion engine according to the present invention includes a component body formed of titanium or a titanium alloy, a surface hardened layer formed on the surface of the component main body, and a diamond-like carbon film provided on the surface hardened layer. And a titanium layer or a titanium alloy layer provided between the surface hardened layer and the diamond-like carbon film.

In a preferred embodiment, the titanium layer or the titanium alloy layer has a thickness of 100 nm to 1500 nm.

  In a preferred embodiment, the surface hardened layer is a titanium oxide layer.

  In a preferred embodiment, the sliding component for an internal combustion engine according to the present invention is a connecting rod including a small end portion and a large end portion, and a connecting portion that connects the small end portion and the large end portion to each other. .

  In a preferred embodiment, the hardened surface layer, the titanium layer or the titanium alloy layer, and the diamond-like carbon film are provided on an inner peripheral surface of at least one of the small end portion and the large end portion. ing.

  In a preferred embodiment, the surface hardened layer, the titanium layer or the titanium alloy layer, and the diamond-like carbon film are provided on the thrust surface of the large end.

  The internal combustion engine by this invention is provided with the sliding component for internal combustion engines which has the said structure.

  A transportation device according to the present invention includes an internal combustion engine having the above-described configuration.

  A method of manufacturing a sliding component for an internal combustion engine according to the present invention includes a step of preparing a component main body formed of titanium or a titanium alloy, a step of forming a surface hardened layer on the surface of the component main body, Forming a titanium layer or a titanium alloy layer, and forming a diamond-like carbon film on the titanium layer or the titanium alloy layer.

  In a preferred embodiment, in the step of forming the titanium layer or the titanium alloy layer, the titanium layer or the titanium alloy layer is formed to a thickness of 100 nm to 1500 nm.

  In a preferred embodiment, in the step of forming the surface hardened layer, the surface of the component body is subjected to an oxidation treatment to form a titanium oxide layer as the surface hardened layer.

  In a preferred embodiment, the method for manufacturing a sliding component for an internal combustion engine according to the present invention includes a step of removing the outermost portion of the titanium oxide layer before the step of forming the titanium layer or the titanium alloy layer. In addition.

  In the sliding component for an internal combustion engine according to the present invention, a surface hardened layer is formed on the surface of a component body made of titanium or a titanium alloy, and a diamond-like carbon film is provided on the surface hardened layer. By providing such a hardened surface layer and a diamond-like carbon film, the seizure resistance and wear resistance of the sliding component are improved, and the friction coefficient of the sliding component surface is reduced. In the sliding component according to the present invention, a titanium layer or a titanium alloy layer is further provided between the surface hardened layer and the diamond-like carbon film. Since the titanium layer and the titanium alloy layer have high adhesion to both the surface hardened layer and the DLC film, the titanium layer or the titanium alloy layer is provided between the surface hardened layer and the diamond-like carbon film. This improves the adhesion of the diamond-like carbon film. Therefore, excellent impact resistance can be realized.

From the viewpoint of achieving both excellent impact resistance and high productivity, the titanium layer or the titanium alloy layer preferably has a thickness of 100 nm to 1500 nm. When the thickness is less than 100 nm, sufficient adhesion of the diamond-like carbon film cannot be ensured, and the impact resistance may not be sufficiently improved. On the other hand, when the thickness exceeds 1500 nm, the time required for forming the titanium layer or the titanium alloy layer (film formation time) becomes long, and productivity may be lowered.

  From the viewpoint of production cost, the surface hardened layer is preferably a titanium oxide layer. The titanium oxide layer can be formed in the atmosphere and does not require a source gas as in the case of forming a titanium nitride layer or a titanium carbide layer. Further, it is not necessary to use a plasma CVD apparatus or the like for the formation. Therefore, the titanium oxide layer can be formed at a low cost.

  The sliding component according to the present invention is, for example, a connecting rod. The connecting rod includes a small end portion and a large end portion, and a connecting portion that connects the small end portion and the large end portion to each other. The small end has a through hole for passing a piston pin and is connected to the piston. On the other hand, the large end portion has a through hole for passing a crank pin, and is connected to the crankshaft.

  The above laminated structure including a hardened surface layer, a titanium layer or a titanium alloy layer, and a diamond-like carbon film is preferably provided in a portion of the connecting rod that requires excellent sliding characteristics. Is preferably provided on the inner peripheral surface of at least one of the small end and the large end. Moreover, it is also preferable that said laminated structure is provided in the thrust surface of the large end part.

  The sliding component according to the present invention is suitably used for various internal combustion engines. By using the sliding component according to the present invention in which the component body is made of titanium or a titanium alloy (that is, lightweight), the internal combustion engine can be reduced in weight. Further, since the inertial force can be reduced by using the lightweight sliding component according to the present invention, the vibration of the internal combustion engine can be reduced and the response can be improved. Furthermore, since the friction coefficient of the diamond-like carbon film is low, the friction loss can be reduced by using the sliding component according to the present invention. Therefore, high fuel consumption and high output can be achieved. Moreover, the diamond-like carbon film has low opponent attack. Therefore, when the sliding component according to the present invention is used, the wear of the counterpart material can be reduced, and the durability of the internal combustion engine is improved.

  The internal combustion engine provided with the sliding component according to the present invention is suitably used for various transportation equipment including a motorcycle.

  In the method for manufacturing a sliding component for an internal combustion engine according to the present invention, a step of forming a titanium layer or a titanium alloy layer is performed between the step of forming the surface hardened layer and the step of forming the diamond-like carbon film. . Therefore, according to the manufacturing method of the present invention, a sliding component for an internal combustion engine in which a titanium layer or a titanium alloy layer is provided between the hardened surface layer and the diamond-like carbon film can be obtained. Since the titanium layer and the titanium alloy layer have high adhesion to both the surface hardened layer and the DLC film, the titanium layer or the titanium alloy layer is provided between the surface hardened layer and the diamond-like carbon film. This improves the adhesion of the diamond-like carbon film. Therefore, excellent impact resistance can be realized.

  From the viewpoint of achieving both excellent impact resistance and high productivity, in the step of forming the titanium layer or titanium alloy layer, the titanium layer or titanium alloy layer is preferably formed to a thickness of 100 nm to 1500 nm. . When the thickness is less than 100 nm, sufficient adhesion of the diamond-like carbon film cannot be ensured, and the impact resistance may not be sufficiently improved. On the other hand, when the thickness exceeds 1500 nm, the time required for the step of forming the titanium layer or the titanium alloy layer becomes long, and the productivity may be lowered.

  From the viewpoint of manufacturing cost, it is preferable that a titanium oxide layer is formed as the surface hardened layer by subjecting the surface of the component main body to an oxidation treatment in the step of forming the surface hardened layer. The titanium oxide layer can be formed in the atmosphere and does not require a source gas as in the case of forming a titanium nitride layer or a titanium carbide layer. Further, it is not necessary to use a plasma CVD apparatus or the like for the formation. Therefore, the step of forming the titanium oxide layer can be performed at a low cost.

  When the titanium oxide layer is formed as the surface hardened layer, it is preferable to perform a step of removing the outermost portion of the titanium oxide layer before the step of forming the titanium layer or the titanium alloy layer. Since the outermost part of the titanium oxide layer is a brittle part called an oxide scale, by removing this part, the adhesion of the titanium layer and the titanium alloy layer to the surface hardened layer (titanium oxide layer) is improved. It can be further improved.

  According to the present invention, the adhesion of a DLC film provided on the surface of a sliding component made of titanium or a titanium alloy can be improved, and excellent impact resistance can be realized.

It is a top view which shows typically the connecting rod 1 in suitable embodiment of this invention. It is sectional drawing which shows typically the connecting rod 1 in suitable embodiment of this invention. It is sectional drawing which shows typically the laminated structure formed in the sliding contact site | part of the connecting rod 1 in suitable embodiment of this invention. It is an electron micrograph which shows the connecting rod surface of the comparative example after performing a Rockwell impression test. It is an electron micrograph which shows the connecting rod 1 surface of the Example after performing a Rockwell impression test. It is sectional drawing which shows typically the other example of the laminated structure formed in the sliding contact site | part of the connecting rod 1 in suitable embodiment of this invention. It is sectional drawing which shows typically the internal combustion engine 100 provided with the connecting rod 1 in suitable embodiment of this invention. It is a side view which shows typically the motorcycle provided with the internal combustion engine 100 shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following, a connecting rod (sometimes referred to as a “connecting rod”) will be described as an example. However, the present invention is not limited to a connecting rod, and is suitably used for sliding parts for internal combustion engines in general. It is done.

  1 and 2 show a connecting rod 1 according to this embodiment. FIG. 1 is a plan view schematically showing the connecting rod 1, and FIG. 2 is a cross-sectional view taken along line 2A-2A 'in FIG.

  The connecting rod 1 is made of titanium or a titanium alloy. As shown in FIGS. 1 and 2, the connecting rod 1 includes a small end portion 10 and a large end portion 20, and a connecting portion 30 that connects the small end portion 10 and the large end portion 20 to each other.

The connection part 30 has a rod-like shape. A small end portion 10 is provided at one end of the connecting portion 30, and a large end portion 20 is provided at the other end. The small end portion 10 is formed with a through hole (referred to as “piston pin hole”) 12 through which the piston pin passes. On the other hand, a through hole (referred to as “crank pin hole”) 22 through which the crank pin is passed is formed in the large end portion 20.

  The inner peripheral surface 10a of the small end portion 10, the inner peripheral surface 20a of the large end portion 20, and the thrust surface 20b of the large end portion 20 are in sliding contact with other components. In the present embodiment, a laminated structure including a diamond-like carbon (DLC) film is formed in at least one (preferably all) of these portions (sliding contact portions). Hereinafter, this stacked structure will be described more specifically with reference to FIG. FIG. 3 is a cross-sectional view schematically showing a laminated structure formed in the sliding contact portion.

  The laminated structure shown in FIG. 3 includes a component body 1a, a surface hardened layer 1b, a titanium layer 2, and a DLC film 3. The component main body 1a, the surface hardened layer 1b, the titanium layer 2, and the DLC film 3 are laminated in this order from the inside of the connecting rod 1.

  The component body (connecting rod body) 1a is made of titanium or a titanium alloy. That is, the component main body 1a is made of pure titanium or an alloy of titanium and another metal element.

  The surface hardened layer 1b is formed on the surface of the component main body 1a. The surface hardened layer 1b is a layer harder than the component main body 1a formed by the hardening process, and specifically includes a titanium oxide layer, a titanium nitride layer, a titanium carbide layer, and the like.

  The titanium layer 2 is provided between the surface hardened layer 1 b and the DLC film 3. The titanium layer 2 is provided directly (without interposing other layers) on the surface hardened layer 1b.

  The DLC film 3 is a hard carbon film having an amorphous structure. The DLC film 3 is provided on the titanium layer 2. That is, the DLC film 3 is provided via the titanium layer 2 on the surface hardened layer 1b.

  As described above, in the present embodiment, the surface hardened layer 1b is formed on the surface of the component main body 1a formed of titanium or a titanium alloy, and the DLC film 3 is provided on the surface hardened layer 1b. By providing such a hardened surface layer 1b and the DLC film 3, the seizure resistance and wear resistance of the connecting rod 1 are improved, and the friction coefficient of the connecting rod 1 surface is reduced. In the present embodiment, a titanium layer 2 is further provided between the surface hardened layer 1 b and the DLC film 3. Since the titanium layer 2 has high adhesion to both the surface hardened layer 1b and the DLC film 3, the titanium layer 2 is provided between the surface hardened layer 1b and the DLC film 3, so that the DLC film 3 Improved adhesion. Therefore, excellent impact resistance can be realized.

Conventionally, it is known to provide an intermediate layer such as a chromium layer in order to improve the adhesion of the DLC film to the component surface. However, since the chromium layer has low adhesion to the surface hardened layer, sufficient impact resistance cannot be realized even if the chromium layer is provided on the surface hardened layer. Of course, if a chromium layer is directly provided on the surface of the component body without forming a hardened surface layer, the adhesion between the component body and the chromium layer can be ensured. However, in this case, since the surface of the component body is soft because the hardened surface layer is not formed, the component body is locally plastically deformed (indentation due to contamination components in the lubricating oil or sliding at the edge of the mating material). The DLC film that can no longer follow the deformation of the component main body is peeled and worn. As in the present embodiment, by providing the surface hardened layer 1b on the surface of the component main body 1a, local plastic deformation of the component main body 1a can be prevented. Further, the conventional intermediate layer such as a chromium layer has low adhesion to the surface hardened layer 1b, but the surface hardened layer 1b and the DLC film 3 are both formed on the surface hardened layer 1b as in the present embodiment. By providing the titanium layer 2 with excellent adhesion, sufficient impact resistance can be obtained.

  In this embodiment, the titanium layer 2 is provided between the surface hardened layer 1b and the DLC film 3, but a titanium alloy layer may be provided instead of the titanium layer 2. Since the titanium alloy layer also has high adhesion to both the surface hardened layer 1b and the DLC film 3, the same effect can be obtained by providing the titanium alloy layer between the surface hardened layer 1b and the DLC film 3. Can be obtained. There is no particular limitation on the composition of the titanium alloy layer.

  From the viewpoint of achieving both excellent impact resistance and high productivity, the titanium layer 2 (or titanium alloy layer) preferably has a thickness of 100 nm to 1500 nm. If the thickness is less than 100 nm, sufficient adhesion of the DLC film 3 cannot be ensured, and the impact resistance may not be sufficiently improved. On the other hand, when the thickness exceeds 1500 nm, the time required for forming the titanium layer 2 (or titanium alloy layer) (film formation time) becomes long, and productivity may be lowered.

From the viewpoint of manufacturing cost, the surface hardened layer 1b is preferably a titanium oxide (TiO ₂ ) layer. The titanium oxide layer can be formed in the atmosphere and does not require a source gas as in the case of forming a titanium nitride layer or a titanium carbide layer. Further, it is not necessary to use a plasma CVD apparatus or the like for the formation. Therefore, the titanium oxide layer can be formed at a low cost.

  1 and 2 show a connecting rod 1 of a type called an integral type, but the present invention is not limited to this. The present invention is also suitably used for a split type connecting rod having a large end divided into two.

  Then, the manufacturing method of the connecting rod 1 in this embodiment is demonstrated.

  First, a component main body 1a formed from titanium or a titanium alloy is prepared. The component main body 1a can be formed by various methods known as connecting rod manufacturing methods. As the titanium alloy, those having various compositions can be used. For example, a Ti-6Al-4V alloy or a β-type titanium alloy can be preferably used.

  Next, the surface hardened layer 1b is formed on the surface of the component main body 1a. The surface hardened layer 1b does not need to be formed on the entire surface of the component main body 1a, and may be formed on the surface of a part that requires excellent seizure resistance and wear resistance. That is, the hardened surface layer 1b may be formed on at least a part of the surface of the component main body 1a. The thickness of the surface hardened layer 1b is preferably 50 μm or more and 150 μm or less. If the thickness is less than 50 μm, wear and seizure may occur due to insufficient slidability. On the other hand, if the thickness exceeds 150 μm, the thick embrittlement layer may reduce the fatigue strength and cause damage.

  When the surface hardened layer 1b is a titanium oxide layer, the surface of the component main body 1a is oxidized. The oxidation treatment is performed, for example, by heating the component main body 1a to 600 ° C. or higher for 30 minutes to 8 hours in an air atmosphere. When the surface hardened layer 1b is a titanium nitride layer, the surface of the component main body 1a is subjected to nitriding treatment. When the surface hardened layer 1b is a titanium carbide layer, the surface of the component main body 1a is carbonized. Processing is performed.

  Subsequently, the titanium layer 2 is formed on the surface hardened layer 1b. The titanium layer 2 can be formed by, for example, a sputtering method. As already described, a titanium alloy layer may be formed in place of the titanium layer 2. For the reasons already described, the titanium layer 2 (or titanium alloy layer) is preferably formed to a thickness of 100 nm to 1500 nm.

  Thereafter, a DLC film 3 is formed on the titanium layer 2. The DLC film 3 can be formed by a CVD (chemical vapor deposition) method or a PVD (physical vapor deposition) method. As the CVD method, for example, a plasma CVD method can be suitably used, and as the PVD method, for example, a sputtering method or an ion plating method can be suitably used. The thickness of the DLC film 3 is preferably 1 μm or more and 6 μm or less. If the thickness is less than 1 μm, it may be worn due to insufficient wear resistance. On the other hand, if the thickness exceeds 6 μm, peeling may occur due to insufficient adhesion.

  Thus, the connecting rod 1 in this embodiment can be manufactured.

  In addition, when forming a titanium oxide layer as the surface hardening layer 1b, it is preferable to remove the outermost part of a titanium oxide layer before the process of forming the titanium layer 2 (or titanium alloy layer). Since the outermost part of the titanium oxide layer is a brittle part called an oxide scale, the surface hardened layer (titanium oxide layer) 1b of the titanium layer 2 (or titanium alloy layer) is removed by removing this part. The adhesiveness with respect to can be improved.

When removing the oxide scale, from the viewpoint of sufficiently increasing the adhesion of the titanium layer 2, the Vickers hardness HV (0.1) of the outermost surface of the titanium oxide layer after the removal is preferably 400 or more. . In addition, if there are large irregularities on the surface of the titanium oxide layer, it causes a decrease in adhesion. Therefore, the surface roughness of the titanium oxide layer after removal is 1.6 μm or less at the maximum height Rz, 10-point average The roughness Rz _JIS is preferably 3.2 μm or less.

  The removal of the oxide scale is preferably performed by barrel polishing. When the oxide scale is removed by barrel polishing, it is easy to reduce the surface roughness.

  Here, the same structure as the connecting rod 1 of this embodiment except that the connecting rod 1 (example) in the present embodiment actually manufactured as described below and a chromium layer and a chromium nitride layer instead of the titanium layer 2 are included. The result of having evaluated the adhesiveness of the DLC film 3 about the connecting rod of the comparative example which has these is demonstrated.

(Example)
First, a component body 1a made of a titanium alloy (specifically, Ti-6Al-4V alloy) was prepared, and degreasing treatment was performed on the component body 1a. Next, the component main body 1a was heated to 800 ° C. in an air atmosphere for 60 minutes to form a titanium oxide layer as the hardened surface layer 1a. The formed titanium oxide layer had a thickness of 60 μm.

  Subsequently, the outermost surface portion (oxide scale) of the titanium oxide layer was removed using a centrifugal barrel polishing machine. Specifically, a portion from the outermost surface to a depth of 8 μm was removed. Further, by this polishing, a rough portion (a portion with many irregularities) of the titanium oxide layer was removed, and the maximum height Rz of the surface was set to 1.6 μm or less.

  Next, the component main body 1a from which the oxide scale was removed was introduced into the chamber of the sputtering apparatus. Subsequently, evacuation was performed until the pressure in the chamber reached 0.4 Pa, and heating was performed using a heater so that the temperature in the chamber became 200 ° C. In this state, argon gas was introduced into the chamber, and the surface of the titanium oxide layer was sputtered for 30 minutes to perform ion bombardment to activate and clean the surface.

Subsequently, a titanium layer 2 having a thickness of 700 nm was formed on the titanium oxide layer by performing sputtering for 40 minutes using pure titanium as a target. Thereafter, a DLC film 3 having a thickness of 2300 nm was formed on the titanium layer 2 by performing plasma CVD in a hydrocarbon gas atmosphere at a pressure of 1 Pa in a chamber of the plasma CDV apparatus.

(Comparative example)
A connecting rod was manufactured in the same manner as in the example except that a chromium layer having a thickness of 300 nm and a chromium nitride layer having a thickness of 400 nm were formed in this order instead of the titanium layer 2. The chromium layer was formed by sputtering using chromium as a target, and the chromium nitride layer was formed by performing sputtering in a state where nitrogen gas was introduced.

(Adhesion evaluation test)
Rockwell indentation tests (C scale) were performed on the connecting rods of the examples and comparative examples. Specifically, an indenter was driven into the surfaces of the connecting rods of Examples and Comparative Examples, and the peeled state of the DLC film was observed. FIG. 4 shows an electron micrograph of the surface of the connecting rod of the comparative example, and FIG. 5 shows an electron micrograph of the surface of the connecting rod 1 of the example.

  In the connecting rod of the comparative example, as shown in FIG. 4, it can be seen that the DLC film is peeled over a wide region outside the indentation, and the adhesion of the DLC film is low. On the other hand, in the connecting rod 1 of the example, as shown in FIG. 5, the DLC film 3 is peeled almost only in the indented portion, that is, only in the portion where the large plastic deformation is applied. It turns out that the nature is very high.

  As described above, by providing the titanium layer 2 between the surface hardened layer 1b and the DLC film 3, the adhesion of the DLC film 3 is improved. 3 illustrates the configuration in which only the titanium layer 2 is provided between the surface hardened layer 1b and the DLC film 3, but as shown in FIG. An intermediate layer 4 may be provided therebetween. The intermediate layer 4 is, for example, a chromium layer, a silicon layer, a tungsten layer, or a composite layer thereof. Further, the intermediate layer 4 may be a layer in which a metal element or a non-metal element and DLC are mixed, and the ratio thereof changes along the thickness direction (referred to as a “DLC gradient layer”). . The DLC gradient layer is, for example, a tungsten-DLC layer or a silicon-DLC layer.

  The intermediate layer 4 as illustrated can gradually change the physical properties such as Young's modulus and hardness, and can relieve the residual stress with respect to the upper and lower layers. By providing, the adhesion of the DLC film 3 can be further improved, and more excellent impact resistance can be realized. 6 shows a configuration in which one intermediate layer 4 is provided between the titanium layer 2 and the DLC film 3, but a plurality of intermediate layers 4 (that is, two or more layers) may be provided.

  The connecting rod 1 in this embodiment is suitably used for various internal combustion engines. FIG. 7 shows an internal combustion engine 100 including the connecting rod 1 in the present embodiment. The internal combustion engine 100 includes a crankcase 110, a cylinder block 120, and a cylinder head 130.

  A crankshaft 111 is accommodated in the crankcase 110. The crankshaft 111 has a crankpin 112 and a crank web 113.

  A cylinder block 120 is provided on the crankcase 110. The cylinder block 120 is fitted with a cylindrical cylinder sleeve 121, and the piston 122 is provided so as to reciprocate within the cylinder sleeve 121.

A cylinder head 130 is provided on the cylinder block 120. The cylinder head 130 forms a combustion chamber 131 together with the piston 122 and the cylinder sleeve 121 of the cylinder block 120. The cylinder head 130 has an intake port 132 and an exhaust port 133. An intake valve 134 for supplying air-fuel mixture into the combustion chamber 131 is provided in the intake port 132, and an exhaust valve 135 for exhausting the combustion chamber 131 is provided in the exhaust port 133. Yes.

  Piston 122 and crankshaft 111 are connected by connecting rod 1. Specifically, the piston pin 123 of the piston 122 is inserted into the through hole of the small end portion 10 of the connecting rod 1, and the crank pin 112 of the crankshaft 111 is inserted into the through hole of the large end portion 20, As a result, the piston 122 and the crankshaft 111 are connected. A roller bearing (rolling bearing) 114 is provided between the inner peripheral surface of the through hole of the large end portion 20 and the crank pin 112.

  By using the connecting rod 1 in the present embodiment in which the component main body 1a is formed of titanium or a titanium alloy (that is, lightweight), the internal combustion engine 100 can be reduced in weight. Moreover, since the inertial force can be reduced by using the lightweight connecting rod 1 in the present embodiment, the vibration of the internal combustion engine 100 can be reduced and the response can be improved. Furthermore, since the friction coefficient of the DLC film 3 is low, the friction loss can be reduced by using the connecting rod 1 in the present embodiment. Therefore, high fuel consumption and high output can be achieved. Moreover, the DLC film 3 has a low opponent aggression property. Therefore, when the connecting rod 1 in the present embodiment is used, the wear of the counterpart material can be reduced, and the durability of the internal combustion engine 100 is improved.

  The internal combustion engine 100 provided with the connecting rod 1 in the present embodiment is suitably used for various transport devices including a motorcycle. FIG. 8 shows a motorcycle including the internal combustion engine 100 shown in FIG.

  In the motorcycle shown in FIG. 8, a head pipe 302 is provided at the front end of the main body frame 301. A front fork 303 is attached to the head pipe 302 so as to be able to swing in the left-right direction of the vehicle. A front wheel 304 is rotatably supported at the lower end of the front fork 303.

  A seat rail 306 is attached so as to extend rearward from the upper rear end of the main body frame 301. A fuel tank 307 is provided on the main body frame 301, and a main seat 308 a and a tandem seat 308 b are provided on the seat rail 306.

  A rear arm 309 extending rearward is attached to the rear end of the main body frame 301. A rear wheel 310 is rotatably supported at the rear end of the rear arm 309.

  The internal combustion engine 100 is held at the center of the main body frame 301. A radiator 311 is provided in front of the internal combustion engine 100. An exhaust pipe 312 is connected to the exhaust port of the internal combustion engine 100, and a muffler 313 is attached to the rear end of the exhaust pipe 312.

  A transmission 315 is connected to the internal combustion engine 100. A drive sprocket 317 is attached to the output shaft 316 of the transmission 315. The drive sprocket 317 is connected to the rear wheel sprocket 319 of the rear wheel 310 via a chain 318. The transmission 315 and the chain 318 function as a transmission mechanism that transmits the power generated by the internal combustion engine 100 to the drive wheels.

In the present embodiment, the present invention has been described by taking the connecting rod 1 as an example. However, the present invention is not limited to the connecting rod 1 and is widely used for sliding parts for internal combustion engines in general. For example, the present invention is also suitably used for engine valves and valve lifters.

  According to the present invention, the adhesion of a DLC film provided on the surface of a sliding component made of titanium or a titanium alloy can be improved, and excellent impact resistance can be realized. The internal combustion engine provided with the sliding parts according to the present invention is suitably used for various transportation equipment such as passenger cars, motorcycles, buses, trucks, tractors, airplanes, motor boats, and civil engineering vehicles.

DESCRIPTION OF SYMBOLS 1 Connecting rod 1a Component main body 1b Surface hardening layer 2 Titanium layer 3 Diamond like carbon (DLC) film | membrane 4 Intermediate layer 10 Small end part 10a Inner peripheral surface of a small end part 12 Through hole (piston pin hole) of a small end part
20 Large end portion 20a Inner peripheral surface of large end portion 22 Through hole (crank pin hole) of large end portion
30 connecting portion 100 internal combustion engine

Claims (10)

A component body formed from titanium or a titanium alloy;
A hardened surface layer formed on the surface of the component body;
A diamond-like carbon film provided on the surface hardened layer;
A titanium layer or a titanium alloy layer provided between the surface hardened layer and the diamond-like carbon film,
The surface hardened layer is a titanium oxide layer,
The surface hardened layer can have a thickness of less than 150μm or 50 [mu] m,
Vickers hardness HV (0.1) of the outermost surface of the surface hardened layer is 400 or more,
A surface roughness of the hardened surface layer is a sliding part for an internal combustion engine having a maximum height Rz of 1.6 μm or less or a ten-point average roughness Rz _JIS of 3.2 μm or less .   The sliding component for an internal combustion engine according to claim 1, wherein the titanium layer or the titanium alloy layer has a thickness of 100 nm to 1500 nm. With a small end and a large end,
The sliding component for an internal combustion engine according to claim 1, wherein the connecting rod includes a connecting portion that connects the small end portion and the large end portion to each other.   The surface hardening layer, the titanium layer or the titanium alloy layer, and the diamond-like carbon film are provided on an inner peripheral surface of at least one of the small end portion and the large end portion. Sliding parts for internal combustion engines.   5. The sliding component for an internal combustion engine according to claim 3, wherein the hardened surface, the titanium layer or the titanium alloy layer, and the diamond-like carbon film are provided on the thrust surface of the large end. .   An internal combustion engine comprising the sliding component for an internal combustion engine according to any one of claims 1 to 5.   A transportation device comprising the internal combustion engine according to claim 6. Preparing a component body formed of titanium or a titanium alloy;
Forming a hardened surface layer on the surface of the component body;
Forming a titanium layer or a titanium alloy layer on the surface hardened layer;
Forming a diamond-like carbon film on the titanium layer or titanium alloy layer;
Including
In the step of forming the surface hardened layer, a titanium oxide layer is formed as the surface hardened layer by subjecting the surface of the component body to an oxidation treatment,
The surface hardened layer can have a thickness of less than 150μm or 50 [mu] m,
Vickers hardness HV (0.1) of the outermost surface of the surface hardened layer is 400 or more,
The surface hardened layer has a surface roughness of 1.6 μm or less at the maximum height Rz or 3.2 μm or less at the ten-point average roughness Rz _JIS , which is a method for manufacturing a sliding component for an internal combustion engine.   The method for manufacturing a sliding component for an internal combustion engine according to claim 8, wherein in the step of forming the titanium layer or the titanium alloy layer, the titanium layer or the titanium alloy layer is formed to a thickness of 100 nm or more and 1500 nm or less.   The method for manufacturing a sliding component for an internal combustion engine according to claim 8 or 9, further comprising a step of removing the outermost portion of the titanium oxide layer before the step of forming the titanium layer or the titanium alloy layer.

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