JP2004162895A - Link mechanism for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a link mechanism for an internal combustion engine, superior in wear resistance and lubricating performance. <P>SOLUTION: The link mechanism for the internal combustion engine 10 having a piston 20 for reciprocating in a cylinder comprises a pin member 44 having oscillating motion and a bearing member 43 having slide contact with the pin member 44. A surface roughness Ra of the sliding face of the pin member 44 is 0.10 μm or less. Low friction surface treatment is applied to at least one of the sliding face of the pin member 44 and the sliding face of the bearing member 43. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a link mechanism for an internal combustion engine.
[0002]
[Prior art]
2. Description of the Related Art A variable compression ratio mechanism of an internal combustion engine having a piston that reciprocates in a cylinder includes a link mechanism having a connecting pin that swings (see, for example, Patent Documents 1 to 3).
[0003]
The connection pin in such a link mechanism comes into contact with the bush pressed into the pin bearing portion and slides while swinging in a range of, for example, 10 degrees or more and 50 degrees or less.
[0004]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2002-21592 [Patent Document 2]
JP 2002-47955 A [Patent Document 3]
JP-A-2002-54468 [0005]
[Problems to be solved by the invention]
However, when a large combustion pressure or a piston inertia force acts, a load applied to the connecting pin and the pin bearing increases, and the pin load is deformed by the input load. The deformation of the pin bearing changes the shape of the sliding surface, thus deteriorating the sliding state.
[0006]
Further, since the swing angle is relatively small and it is difficult to supply the lubricating oil, a particularly severe lubrication state is obtained at the turning position of the swing motion.
[0007]
Therefore, for example, at the time of startup or when the oil temperature is high where the lubrication state of the sliding surface is not good, there is a problem that the wear and friction loss increase, and the pin bearing portion may be seized.
[0008]
SUMMARY OF THE INVENTION The present invention has been made to solve the problems associated with the conventional technology, and has as its object to provide a link mechanism for an internal combustion engine having good wear resistance and lubricity.
[0009]
[Means for Solving the Problems]
The present invention for achieving the above object is a link mechanism of an internal combustion engine having a piston reciprocating in a cylinder. The link mechanism has a pin member that swings and a bearing member that slides on the pin member. The surface roughness Ra of the sliding surface of the pin member is 0.10 μm or less, and at least one of the sliding surface of the pin member and the sliding surface of the bearing member is subjected to a low friction surface treatment.
[0010]
【The invention's effect】
In the present invention configured as described above, a portion having a small surface roughness Ra on the sliding surface and subjected to low friction surface treatment exhibits a self-lubricating action. Therefore, even in a situation in which lubrication, in which the oil film becomes thin, is severe, the abrasion resistance and lubricity are excellent. For example, even if a large combustion pressure or a piston inertia force acts, it is possible to prevent an increase in wear and friction loss and seizure of a bearing member. That is, a link mechanism for an internal combustion engine having good wear resistance and lubricity can be provided.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0012]
FIG. 1 is a sectional view of an internal combustion engine 10 according to an embodiment of the present invention. The internal combustion engine 10 includes a piston 20 that reciprocates in a cylinder, and has a link mechanism applied to a variable compression ratio mechanism for variably controlling the engine compression ratio.
[0013]
The link mechanism has an upper link 30, a lower link 40, a crankshaft 50, a control link 60, and a control shaft 70.
[0014]
One end of the upper link 30 is rotatably supported by a piston 20 that receives a combustion pressure via a piston pin 21. The other end of the upper link 30 is swingably connected to and supported by the lower link 40 via a first connecting pin (a swinging pin member) 44.
[0015]
The lower link 40 is rotatably mounted on the crankpin 51 of the crankshaft 50, and rotatably supports one end of the control link 60 via the second connection pin 47.
[0016]
The crankshaft 50 is rotatably supported by a main body of the internal combustion engine block via a main bearing, and is used for extracting power. Reference numeral 52 is a main journal (crank journal) of the crankshaft 50.
[0017]
The control link 60 is rotatably supported by the eccentric cam 71 of the control shaft 70 via the other end located opposite to the one end rotatably supported by the lower link 40.
[0018]
The control shaft 70 is rotatably supported by the main body of the internal combustion engine block, and forcibly rotates with respect to the main body of the internal combustion engine block, thereby changing a piston stroke with respect to a crank angle and changing an engine compression ratio. . That is, the swing fulcrum position of the control link 60 changes according to the rotation position of the eccentric cam 71 of the control shaft 70, so that the top dead center position of the piston 10 changes.
[0019]
2 is an enlarged view of a lower link of the internal combustion engine shown in FIG. 1, FIG. 3 is a perspective view of a first portion of the lower link, FIG. 4 is a perspective view of a second portion of the lower link, and FIG. FIG. 2 is a diagram for explaining a connection structure between an upper link and a lower link shown in FIG.
[0020]
The lower link 40 is divided into a forked first portion 40A having a semicircular concave portion 41A and a forked second portion 40B having a semicircular concave portion 41B. The recesses 41A and 41B form the bearing portion 41 of the crankpin 51 by connecting the first portion 40A and the second portion 40B by a fastening member 42 such as a bolt.
[0021]
The forked portion of the first portion 40A has a pair of first pin bearings (bearing members) 43 for connecting the upper link 30 and the lower link 40. The first connecting pin 44 is press-fitted and fitted into the first pin bearing 43 in a state where the pin bearing 31 of the upper link 30 is sandwiched between the forked portions of the first portion 40A. Therefore, the first connecting pin 44 is in direct sliding contact with the first pin bearing 43.
[0022]
Note that the first connection pin 44 and the pin bearing 31 of the upper link 30 are an interference fit, and the first connection pin 44 and the first pin bearing 43 of the lower link 40 are set to an intermediate fit. I have.
[0023]
Therefore, the pin bearing portion 31 of the upper link 30 and the first connection pin 44 are fixed and hardly slide. On the other hand, the first connecting pin 44 swings while sliding with respect to the first pin bearing 43 of the lower link 40 based on the rotational movement of the crankshaft 50.
[0024]
That is, in the present embodiment, the first pin bearing 43 of the lower link 40 has a surface that slides with the first connecting pin 44, but the pin bearing 31 of the upper link 30 is No sliding surface.
[0025]
The swing angle of the first connection pin 44 is preferably 10 degrees or more and 90 degrees or less, and is set to 20 degrees in the present embodiment.
[0026]
The input surface pressure due to the combustion pressure or the inertia force when the first connection pin 44 slides, that is, the surface pressure of the sliding portion is, for example, 50 MPa or more and 150 MPa or less, and the maximum surface pressure is in the range of 100 MPa or more and 150 MPa or less. It is appropriate to design with.
[0027]
The second portion 40 </ b> B includes a pair of second pin bearings 45 for swingably connecting the control link 60 to the lower link 40, and a bush 46 press-fitted into the second pin bearing 45.
[0028]
The second connecting pin 47 is press-fitted into the bush 46 in a state where the pin bearing portion of the control link 60 is sandwiched between the forked portions of the second portion 40B. Therefore, the second connecting pin 47 is in direct sliding contact with the bush 46.
[0029]
The lower link 40 has paths (lubricating oil supply paths) 48 and 49 for supplying lubricating oil to the sliding surface. The lubricating oil supply path 48 extends from the bearing 41 of the crankpin 51 to the first pin bearing 43. The lubricating oil supply path 49 extends from the bearing 41 of the crank pin 51 to the bush 46.
[0030]
As described later, since the lubricity of the first pin bearing portion 43 is improved, the lubricating oil supply path 48 can be omitted, the manufacturing process can be simplified, and the number of manufacturing steps can be reduced.
[0031]
Next, the configuration of the first connection pin 44 will be described in detail.
[0032]
The surface of the sliding surface of the first connection pin 44 is subjected to a sulfurizing treatment (low friction surface treatment). The sulfurizing treatment is a treatment for forming a solid lubricating iron sulfide compound film on the surface, for example, an electrolytic plating treatment.
[0033]
In the electroplating process, a ferrite ion, a sulfur compound (sulfur ion), and a chelating agent are contained in a first connecting pin material made of a steel material (for example, SCM420-based chromium molybdenum steel material) that has been heat-treated in advance. An aqueous solution is used.
[0034]
The molar concentration of trivalent iron ions is, for example, in the range of 0.001 to 0.5 mol / L. The pH of the aqueous solution is, for example, 8 or more. The molar concentration of the chelating agent is, for example, in the range of 0.001 to 2.0 mol / L. The molar concentration of the sulfur compound is, for example, in the range of 0.005 to 1.0 mol / L. The current density is, for example, in the range of 1 to 20 A / dm ² .
[0035]
The processing temperature of the aqueous solution is, for example, in the range of 35 to 60 ° C. The sulfurizing treatment is particularly suitable when it is desired to avoid a decrease in the hardness of the base material because the treatment temperature is low. In addition, the fine concave part existing on the surface functions as an oil reservoir.
[0036]
Examples of the substance serving as a source of sulfur ions include the following (a) to (d).
[0037]
(A) Sulfide salts such as potassium sulfide, sodium sulfide and ammonium sulfide. (B) thiosulfates such as potassium thiosulfate, sodium thiosulfate and ammonium thiosulfate. (C) dithiosulfites such as potassium dithiosulfite, sodium dithiosulfite, and ammonium dithiosulfite; (D) Sulfur compounds such as potassium tetrathionate sulfate, sodium tetrathionate sulfate, and ammonium tetrathionate sulfate.
[0038]
Examples of the chelating agent include the following (a) to (l).
[0039]
(A) Aliphatic carboxylic acids such as citric acid, gluconic acid and tartaric acid. (B) Heptonic acid systems such as α-D-glucoheptonic acid, β-D-glucoheptonic acid, α-D-galactoheptonic acid, and β-D-galactoheptonic acid. (C) aromatic compounds such as 5-sulfosalicylic acid, pyrocatechol-3,5-disulfonate and sulfonic acid; (D) Aromatic compounds having an amino group, such as aminonaphthol disulfonate and aminophenolsulfonate.
[0040]
(E) Oxynones such as 8-oxyquinoline, oxine-5-sulfonic acid, and 7-iodooxin-5-sulfonic acid. (F) Aromatic m-aminophenol having an amino group, 3-aminobenzenesulfonic acid 3-amino-4-hydroxybenzenesulfonic acid 3-amino-4-methoxybenzenesulfonic acid 4-amino-3-methylbenzenesulfone Acid aminophenol disulfonic acid 1-amino-2-naphthol-4-sulfonic acid 4-amino-3-hydroxy-1-naphtholsulfonic acid.
[0041]
(G) Nitro group-containing aromatic 3-nitrobenzenesulfonic acid nitrophenol sulfonic acid nitrothiophenol 6-nitro-2-aminophenol-4-sulfonic acid nitronaphthalenesulfonic acid 4,4'-dinitrostilbene-2,2 '-Disulfonic acid. (H) Carboxylic acid-based aminosalityl having an amino group, aminosalicyl 5-amino-2-hydroxybenzoate, 2-aminothiazole-4-carboxylic acid, 2-amino-3-pyridinecarboxylic acid.
[0042]
(I) Carboxylic acid type 3-5-dinitrobenzoic acid having a nitro group 2-hydroxy-3,5-dinitrobenzoic acid nitrophthalic acid nitroterephthalic acid α-nitropropionic acid (J) Alcohol-based amino isophthalic acid amino-1-naphthoic acid aspartic acid aminocresol aminothiophenol aminonitrophenol aminoquinoline aminoquinazine having an amino group.
[0043]
(K) Nitro-containing alcohol-based nitro-1-naphthylamine nitro-1-naphthol nitrohydroquinone 4-nitrotoluene-2-sulfonic acid nitrophenylacetic acid nitro-1-naphthoic acid. (L) Others diethylenetriaminepentaacetic acid metrocaptoethyleneiminoaminodiacetate diethylenetriaminepenta (methylenesulfonic acid) 8-hydroxy-5-nitropyridinenitro-m-tolidine.
[0044]
The quality of the finishing process of the first connecting pin 44 is set in consideration of the sulfurizing process performed after the finishing process. For example, the first connection pin 44 is subjected to a finishing process in which the surface roughness Ra becomes 0.05 μm or less. In the present embodiment, the surface roughness Ra of the first connection pin 44 after the sulfurizing treatment was 0.08 μm as measured by a surface roughness measuring device.
[0045]
The thickness of the vulcanized film (film formed by the vulcanization process) is preferably 1 μm or more and 10 μm or less so that the surface roughness does not significantly change. In consideration of the persistence of self-lubricating effect and conformability, About 5 μm is more preferable. In the present embodiment, when the thickness of the sulfurized film was measured by cross-sectional observation with an electron microscope, it was 4.2 μm.
[0046]
The first pin bearing 43 is also subjected to finishing, and the surface roughness Ra of the sliding surface is set to 0.10 μm or less. In the present embodiment, the measurement result of the surface roughness Ra was 0.07 μm. However, the sliding surface of the first pin bearing 43 can be omitted from finishing and can be subjected to only cutting.
[0047]
As described above, since the sliding surface of the first connection pin 44 has a small surface roughness Ra and a self-lubricating effect of the sulfurized film, the abrasion resistance and the abrasion resistance can be improved even in a severe lubrication condition where the oil film becomes thin. Excellent lubricity.
[0048]
For example, even when the lubrication condition is deteriorated due to the deformation of the first pin bearing portion 43 of the lower link 40, or when a large combustion pressure or a piston inertia force is applied, lubrication at the turning position of the oscillating sliding where lubrication is severe is performed. Nature can be secured.
[0049]
Further, the distance between the swing surface of the first pin bearing 43 and the outer periphery of the first portion 40A can be secured only about 7 mm due to the layout. On the other hand, the thickness of the bush member is about 1.5 mm to 2.0 mm. Therefore, when the bush is press-fitted into the first pin bearing portion 43, the stiffness near the first pin bearing portion 43 is greatly affected.
[0050]
However, in the present embodiment, since the lubricating property of the first connecting pin 44 is improved, the first pin bearing 43 does not require a bush member. Therefore, it is possible to improve the rigidity as compared with the case where the bush member is provided, to suppress the deformation of the first pin bearing portion 43 due to the combustion pressure and the inertial force, and to make the sliding state worse. It is possible to prevent a change in surface shape.
[0051]
As described above, in the present embodiment, the surface of the sliding surface of the first connection pin is subjected to low friction surface treatment (sulfurization treatment), and the surface roughness Ra is 0.10 μm or less. It is. In other words, the sliding surface of the first connecting pin has a small surface roughness Ra, and the portion (sulfurized film) subjected to the low friction surface treatment exhibits a self-lubricating effect. Excellent wear resistance and lubricity even under severe conditions.
[0052]
For example, even if a large combustion pressure or a piston inertia force acts, the entire operation is smooth, and it is possible to prevent wear, increase in friction loss, seizure of the bearing, and galling. Therefore, a link mechanism for an internal combustion engine having good wear resistance and lubricity can be provided.
[0053]
In consideration of the component shape and size, it is preferable to apply a low friction surface treatment to the sliding surface of the first connection pin 44 from the viewpoint of cost effectiveness. However, the low friction surface treatment can be applied to the sliding surface of the first pin bearing portion 43 instead of the sliding surface of the first connecting pin 44, and the same effect can be obtained in this case. . Further, both the sliding surface of the first connecting pin 44 and the sliding surface of the first pin bearing 43 can be subjected to a low friction surface treatment.
[0054]
Next, a modified example of the low friction surface treatment will be described.
[0055]
The low friction surface treatment is not limited to the sulfurizing treatment, and a hard carbon film forming treatment can be applied. The hard carbon film is a film composed of amorphous carbon or hydrogenated carbon, and is aC: H (amorphous carbon or hydrogenated amorphous carbon), iC (eye carbon), DLC (diamond-like carbon or DLC) is also called.
[0056]
The coating treatment for forming the hard carbon coating is not particularly limited, and may be an ion beam evaporation method, a discharge coating method, an ion plating method, a sputtering method (for example, a magnetron sputtering method for increasing a plasma density using a magnetic field), A chemical vapor synthesis method (for example, a plasma vapor synthesis method in which a hydrocarbon gas is plasma-decomposed to form a film) or the like can be appropriately applied.
[0057]
Furthermore, it was found that the seizure resistance was particularly improved when the concentration of hydrogen atoms in the hard carbon film was 1 atomic% or less. This is presumed to be due to the excellent adsorption ability of oil molecules and additives on the surface. Therefore, as a coating treatment for forming a hard carbon coating, an ion plating method or a magnetron sputtering method in which hydrogen is not present in principle in a manufacturing process is preferable.
[0058]
In the present modification, from the viewpoint of the concentration of hydrogen atoms, an ion plating method is applied as a coating process, and the coating process is performed on the surface of the sliding surface of the first connection pin 44 in consideration of cost effectiveness. did.
[0059]
In consideration of the formation of the hard carbon film to be performed after the finishing, the quality of the finishing of the first connecting pin 44 is determined such that the finishing of the first connecting pin 44 has a surface roughness Ra of 0.05 μm or less. Will be applied. In this modification, the surface roughness Ra of the first connection pin 44 after the coating treatment was 0.02 μm as measured by a surface roughness measuring device.
[0060]
In addition, when the hard carbon film is thin, there is a concern that the base may be exposed due to abrasion. On the other hand, when the hard carbon film is thick, there is a risk of peeling due to a stress difference between the film and the base. Therefore, the thickness of the hard carbon film is preferably 0.1 μm or more and 10 μm or less, more preferably 0.5 μm or more and 2 μm or less.
[0061]
In this modification, the thickness of the hard carbon film is set to 0.8 μm (measured by cross-sectional observation using an electron microscope) by adjusting the time of the film forming process. The concentration of hydrogen atoms in the hard carbon film was 0.4 atomic% according to the quantitative determination of the amount of hydrogen using the secondary ion mass spectrometry (SIMS).
[0062]
The first pin bearing 43 is also subjected to finishing, and the surface roughness Ra of the sliding surface is set to 0.10 μm or less. The measurement result of the surface roughness Ra in this modified example was 0.07 μm.
[0063]
As described above, since the sliding surface of the first connecting pin 44 has a small surface roughness Ra and the self-lubricating action of the hard carbon film, even in a situation where the oil film becomes thin and the lubrication is severe, the abrasion resistance and the lubrication can be improved. Excellent in nature. Therefore, also in this modified example, it is possible to provide a link mechanism for an internal combustion engine having good wear resistance and lubricity.
[0064]
The hard carbon coating is disadvantageous in cost as compared with the sulfurized coating, but is excellent in performance such as abrasion resistance, so that it is suitable when importance is attached to maintaining the function of suppressing galling and seizure.
[0065]
It is also preferable to add a metal element to the hard carbon coating in order to promote the reaction with the additive in the oil. As the metal element to be added, Ti, Mo, W, Nb, Fe and the like are preferable, and the addition amount is preferably 4 to 15 atomic%.
[0066]
The hard carbon film to which the metal element is added is easily formed by, for example, applying magnetron sputtering, replacing a part of the target with a metal to be added or a compound containing the metal to be added, and sputtering. be able to.
[0067]
Note that the present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the claims.
[0068]
For example, in the present embodiment, an application example in the link structure between the upper link and the lower link is shown, but the present invention is also applicable to a link structure between the lower link and the control link.
[0069]
Further, the connection between the bearing portion of the upper link and the lower link employs a press-fitting structure, but is not limited thereto. For example, a full float structure (a sliding portion between the bearing portion of the upper link and the first connecting pin is set to a clearance fit, and a sliding portion between the first pin bearing portion of the lower link and the first connecting pin is set to an intermediate fit. (Set structure) can also be applied.
[Brief description of the drawings]
FIG. 1 is a side sectional view of an internal combustion engine according to an embodiment of the present invention.
FIG. 2 is an enlarged view of a lower link of the internal combustion engine shown in FIG.
FIG. 3 is a perspective view relating to a first portion of a lower link.
FIG. 4 is a perspective view relating to a second portion of the lower link.
FIG. 5 is a view for explaining a connection structure between an upper link and a lower link shown in FIG. 1;
[Explanation of symbols]
10 ... internal combustion engine,
20 ... piston,
21 ... Piston pin,
30 ... upper link,
31 ... pin bearing part,
40 ... lower link,
40A: first part,
40B: second part,
41 ... bearing part,
41A: recess,
41B: recess,
42 ... fastening members,
43 ... first pin bearing portion (bearing member);
44 ... first connecting pin (pin member),
45 ... second pin bearing part,
46 ... bush,
47 ... second connecting pin,
48 ... lubricating oil supply path,
49 ... lubricating oil supply path,
50 ... Crankshaft,
51 ... crank pin,
52: Main journal (crank journal),
60 ... control link,
70 ... Control axis,
71: Eccentric cam.

Claims (10)

A link mechanism for an internal combustion engine having a piston that reciprocates in a cylinder,
A pin member that swings and has a bearing member that slides on the pin member,
The surface roughness Ra of the sliding surface of the pin member is 0.10 μm or less,
A link mechanism for an internal combustion engine, wherein a low friction surface treatment is applied to at least one of a sliding surface of the pin member and a sliding surface of the bearing member. The link mechanism according to claim 1, wherein the low friction surface treatment is a sulfurizing treatment. The link mechanism for an internal combustion engine according to claim 2, wherein the thickness of the film formed by the sulfurizing treatment is 1 m or more and 10 m or less. The link mechanism for an internal combustion engine according to claim 1, wherein the low friction surface treatment is a hard carbon film formation treatment. The link mechanism of an internal combustion engine according to claim 4, wherein the thickness of the hard carbon film is 0.1 µm or more and 10 µm or less. The link mechanism of an internal combustion engine according to claim 4 or 5, wherein the concentration of hydrogen atoms in the hard carbon film is 1 atomic% or less. The range of the swing angle of the pin member is 10 degrees or more and 90 degrees or less, and the maximum surface pressure during sliding of the pin member is 100 MPa or more and 150 MPa or less. 7. The link mechanism for an internal combustion engine according to any one of 6. The link mechanism of an internal combustion engine according to any one of claims 1 to 7, wherein the link mechanism of the internal combustion engine is applied to a variable compression ratio mechanism for controlling an engine compression ratio. The variable compression ratio mechanism has an upper link connected to the piston, a lower link rotatably mounted on a crankpin, and a control link swingably connected to the lower link,
The bearing member is formed on the lower link,
The link mechanism according to claim 8, wherein the pin member is applied to swingably connect the upper link to the lower link. The link mechanism for an internal combustion engine according to any one of claims 1 to 9, wherein the bearing member and the pin member are in direct sliding contact with each other.

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