JP2006300224A - Three-piece combination oil ring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a three-piece combination oil ring capable of improving abrasion resistance of a spacer expander ear portion kept into contact with inner peripheral faces of side rails, having high oil controllability as it has a thin width, and preventing fixing of oil combustion residue. <P>SOLUTION: This three-piece combination oil ring is composed of the spacer expander and the pair of side rails supported by the spacer expander, and has a thickness h1 of 1-3 mm, the space expander is composed of a flat metal shaped into the waveform in the piston axial direction, extending in the circumferential direction, and has a pressing piece on its inner peripheral portion for pressing the side rails to a radial outer side, a nitride layer is formed on a sheared face of the pressing piece, a face excluding the nitrided sheared face is covered by a Ni plating film, and thin films composed of only fluorine organic substance are formed on an outermost surface of a face opposite to the side rails, of the spacer expander and faces opposite to the spacer expander, of the side rails. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a three-piece combined oil ring that is mounted on a piston of an internal combustion engine and performs oil control.

FIG. 5 shows a cross-sectional configuration of a general piston ring in an internal combustion engine. The piston 10 is formed with ring grooves 11, 12, and 13 for mounting piston rings. In these ring grooves, two pressure cullings 21 and 22 mainly for the purpose of gas sealing, oil control A pair of combination oil rings 23 mainly for the purpose of oil seal action are mounted. As the piston 6 reciprocates, the outer peripheral sliding surfaces of these rings slide with the inner wall 20 a of the cylinder 20. The combined oil ring shown in FIG. 6 is a pair of axially upper and lower side rails 231 and a spacer extract having an axial waveform that is combined with the side rails 231 and pressed from the inner peripheral side of the side rails 231 to generate tension on the side rails 231 This is a three-piece combined oil ring including a panda 232. The piston axial dimension h1 of the combined oil ring is referred to as the oil ring width. In addition to the axial waveform shown in FIG. 6, the spacer expander has a radial waveform shown in FIG. 7, but is not included in the present invention.

The three-piece combined oil ring having an axially corrugated shape shown in FIG. 6 has a side rail 231 on the radial direction toward the cylinder wall surface and on the upper and lower surfaces of the ring groove depending on the angle α of the ear portion (pressing portion) 50 of the spacer expander 232. It is pressed with a component force in the direction of the axial direction. Therefore, the side rail 231 can exhibit a sealing function on the cylinder wall surface 20a and the upper and lower surfaces of the ring groove. For this reason, the three-piece type oil ring 23 is superior in oil control performance to the conventional two-piece type oil ring. In particular, the three-piece type combined oil ring with a reduced width (smaller h1 dimension) has good followability to the cylinder wall surface 20a and has the above-mentioned side seal function, so that it does not increase oil consumption even at low tension. It has the advantage that friction loss can be reduced. When any one of the side rail outer peripheral surface 231a that slides on the cylinder wall surface 20a, the side rail inner peripheral surface 231b that contacts each other and the ear portion 50 of the spacer expander wears, the spacer expander presses the side rail. Since the force to perform is reduced, the oil scraping function is reduced. In many cases, the wear of the ear portion 50 is larger than the wear of the inner peripheral surface of the side rail. In the recent trend of lower tension, a decrease in the oil scraping function due to wear of the ears leads to an increase in oil consumption. Generally, soft nitriding and gas nitriding have been performed on the entire spacer expander as a countermeasure for wear of the ear. JP-A-56-66429, JP-A-56-66430, JP-A-57-206752, JP-A-58-5456, JP-A-58-163653, JP-A-60- Japanese Patent Application Laid-Open No. 110646 and Japanese Patent Application Laid-Open No. 60-116844 disclose examples in which soft nitriding or gas nitriding is performed on a spacer expander.

On the other hand, in automobile engines, CO2 ↓ emission reduction is required from the viewpoint of preventing global warming, and fuel efficiency is improved. Therefore, reducing the frictional force of each part of the internal combustion engine has become an important issue, and the piston ring plays a large role in solving these issues. In the design of the piston ring, it is effective to reduce the tension of the piston ring, in particular, to reduce the tension of the oil ring, in order to reduce the frictional force. The tension of a conventional three-piece combination oil ring for a gasoline engine is 30 to 50 N (Newton) and occupies about ½ of the tension of the entire piston ring including the Top ring and the 2nd ring. The piston ring tension and the friction loss due to the piston ring are in a proportional relationship. When the piston ring tension is reduced to about half, the piston ring friction loss can be reduced by about 40 to 50%. However, if the conventional three-piece combined oil ring with an oil ring width h1 of 3 to 4 mm is simply made low tension, the gap between the side rail outer peripheral surface and the cylinder wall tends to be larger than before, and the consumption of engine oil is increased. Become. Therefore, it has been found that in order to reduce the frictional force of the oil ring, it is necessary not only to lower the tension of the oil ring but also to reduce the width h1 of the oil ring. In addition, it is thought that reducing the oil ring width decreases the section modulus of the piston ring, improves the followability to the cylinder wall, and improves oil consumption.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a low-strength three-piece combination oil ring that is improved in wear resistance of a spacer expander ear portion that comes into contact with the inner peripheral surface of a side rail and that is thin and has a higher oil control function. There is.

The spacer expander and a pair of side rails supported by the spacer expander is a three-piece combination oil ring having a width h1 of 1 to 3 mm. The spacer expander is formed in a piston axial waveform by a flat metal. The inner peripheral portion has a pressing piece that protrudes in the piston axial direction by shearing of the base material and presses the side rail radially outward. A nitride layer is formed, and the surfaces other than the nitrided shear surface are covered with a Ni plating film, and at least the outermost surface of the spacer expander facing the side rail and / or the spacer of the side rail A three-piece combined oil-retaining film characterized in that a thin film made of only a fluorine-based organic material is formed on the surface facing the expander. Is grayed, combined tension is in 5～15N, fluorinated organic thin film, it is more desirable to include CF3 group and / or CF2 group.

  A spacer expander of a three-piece combination oil ring according to the first invention of the present application is shown in FIG. Common austenitic stainless steel is used for the base material. A nitride layer 50a is formed on the shearing surface of the ear portion 50, and the surface of the spacer expander other than the nitrided shearing surface is covered with a Ni plating film 50b. Usually, when austenitic stainless steel is used as a base material, the surface hardness of the nitrided layer is Hv 1000-1500, and the nitriding depth is 5-30 μm (Hv 700 or more). When the hardness of the nitrided layer is low or the depth is small, the wear of the ear portion is increased and sufficient durability cannot be obtained. If the nitride layer thickness is 30 μm or more, it takes a long time for nitriding, which is not a good idea. Note that the wear resistance is better when a nitride layer is formed on the surface. If there is a (Fe, Cr, Ni,...) 4N phase that is a compound phase having peaks at 2θ = 40 ° and 2θ = 46 ° in Cu-Kα X-ray diffraction, the durability is further increased.

  When the spacer expander that forms the ears by shearing in the vertical waveform is nitrided, the sheared surface that comes into contact with the inner peripheral surface of the side rails of the ears is subjected to strong processing to form a damaged layer, and the material is austenite. Since stainless steel is used, nitridation unevenness is likely to occur in a normal pretreatment because it is less nitrided than other surfaces. If the nitrided layer is shallow, the wear resistance is poor and the durability is not good. In addition, if the nitriding time is increased in order to obtain a thick nitrided layer, the nitrided layer depth of the upper and lower surfaces that are easily nitrided becomes too large, and the fatigue limit of the spacer expander body is lowered, and there is a risk of breaking during use. .

  Moreover, in order to reduce the tension of the three-piece combination oil ring, it is necessary to design the spacer expander with a low tension, but if the tension variation width generated in the manufacturing process is not less than the conventional one, depending on the case, Some oil ring tensions can be zero, which can increase oil consumption. The reason why the tension variation width increases is that the oil ring tension is determined by the degree of diameter reduction in the circumferential direction of the spacer expander, and therefore the variation in the circumferential dimension of the spacer expander and the variation in the elastic modulus of the base material This is a major cause of variations in ring tension. The dimensional variation due to machine accuracy during machining such as cutting is small, and in the nitriding process, the diffusion of nitrogen diffuses the base material and the elastic modulus increases. Therefore, the nitriding depth varies in the nitriding process. It causes variations in length and elastic modulus in the circumferential direction of the expander.

  Therefore, the manufacturing method of the spacer expander of the present application takes the manufacturing process described in Japanese Utility Model Laid-Open No. 4-64658 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2003-28299 (Patent Document 2). The invention of Japanese Utility Model Laid-Open No. 4-64658 is a spacer expander having a plurality of spaced-apart lugs projecting up and down on the inner peripheral side, and having a continuous wave shape in the axial direction. It relates to a spacer expander having a base material surface that has a surface treatment layer for nitriding prevention on the entire surface of the material and has no surface treatment layer for nitriding sheared from the surface of the main body. In order to solve the problem that the fatigue strength of the spacer expander decreases and fatigue breaks during use, an anti-nitriding film such as Sn plating or Cu plating is applied to the surface of the steel strip before forming the spacer expander. In the subsequent molding process, nitriding is performed after forming the ear portion so that the base material is exposed only at the contact portion with the rail portion, and only the base material portion exposed by shearing is nitrided Spacer extract with excellent wear resistance, formed with a nitride prevention layer on the other surface, and because the nitride layer is not formed, the fatigue strength is high and only the ears contacting the inner peripheral surface of the rail ring are nitrided. Disclose the panda. However, there is no description regarding the nitriding method.

  The invention of Japanese Patent Laid-Open No. 2003-28299 is a combined oil ring spacer expander having a pressing piece projecting up and down in the piston axial direction on the inner periphery of the main body, and nitriding only on the surface formed by shearing of the outer pressing piece A spacer expander characterized in that it has a layer and the other surface has a Ni, Cr or Cu coating. Similar to the above-mentioned plan, a nitride expander is prevented from being formed on the entire body, and a spacer expander is formed by nitriding only the ears of the spacer expander formed by shearing. It is disclosed that it can be reduced. In the present invention, there is no description regarding the nitriding method as in the above invention.

  The above inventions are one of the objects of the present invention, and in order to reduce the tension variation of the spacer expander due to the variation in the depth of the nitride layer, no nitride layer is formed on the upper and lower surfaces of the spacer expander. However, the shear surface in contact with the inner peripheral surface of the side rail of the ear part is subjected to strong processing and a work-affected layer is formed, and since austenitic stainless steel is used as the material, it is compared with other main body surfaces There is no solution to the problem that nitriding is difficult and nitriding unevenness is likely to occur.

  Therefore, in the present application, a method of performing gas nitriding after activating the metal surface by introducing a halogen element such as hydrogen chloride gas or ammonium chloride into a gas nitriding furnace prior to gas nitriding or at the time of gas nitriding is adopted. In this nitriding method, the nitride layer can be formed evenly on the shearing surface of the ear portion where the work-affected layer of austenitic stainless steel is present due to the strong activation force of halogen elements such as chlorine. However, the metal plating film for preventing nitriding of Sn, Cu or Cr disclosed in the prior art cannot be used because it is corroded by this chlorine gas. Therefore, in the present invention, only the Ni plating film can be used as the nitriding prevention plating film. Moreover, the thermal expansion coefficient of the Ni plating film is larger than that of the base material austenitic stainless steel. Therefore, when the temperature of the spacer expander is raised, a compressive stress exists on the surface of the spacer expander. The Ni plating film according to the present invention has a thickness of 1 to 10 μm. When the thickness of the Ni plating film is less than 1 μm, the effect of preventing nitriding is not sufficient, and a nitride layer is formed particularly at the corners of the spacer expander, resulting in a large tension variation. If the thickness of the Ni plating film exceeds 10 μm, when the Ni plating film is worn out, the clearance with the ring groove increases, so that oil consumption increases and this is not suitable. Note that the Ni plating film is likely to wear due to its hardness being lowered by nitriding treatment.

  On the other hand, when the lubricating oil burns together with the fuel, carbon-based combustion products are generated and circulate in the engine block mixed with the lubricating oil. Since the three-piece combination oil ring has a complicated shape, these combustion products are likely to adhere to the oil ring, and the once attached combustion product further accumulates in order to inhibit the oil flow in that part. Occurs. The vicinity of the oil ring is also in a temperature environment of 100 to 150 ° C. When it is severe, sticking (stick) with the piston occurs. In particular, sticking tends to occur when the combined tension of the oil ring is designed to be as low as 15 N or less for improving fuel efficiency. Once the sticking occurs, there will be a gap between the outer peripheral surface of the oil ring and the inner peripheral surface of the cylinder. This reduces the oil scraping function and increases engine oil consumption. It becomes a vicious circle, and progresses to a more severe fixation.

  Since the width h1 of the oil ring is reduced to 1 to 2 mm, the area of the oil passage between the spacer expander and the rail ring 52 is narrowed, so this sticking phenomenon is more likely to occur. As a countermeasure against this sticking, it is effective to increase the clearance of the ring groove, which is the difference between the axial width d1 of the oil ring groove of the piston and the oil ring width h1, but increasing the clearance increases the upper and lower of the piston. As the movement increases, the width of the side rail that vibrates up and down in the piston groove increases, which causes groove wear, a decrease in sealing function, and vibration noise. Therefore, it is not desirable to increase the clearance.

  As a means for preventing oil sludge from adhering to or sticking to a three-piece oil ring, a method of applying a fluorine resin film or a resin film containing a fluorine resin has been proposed. For example, JP 2002-310299 A (Patent Document 3) discloses a side rail for a combined oil ring in which a synthetic resin film such as polytetrafluoroethylene (PTFE) is formed on at least one side surface of the side rail. Japanese Patent Application Laid-Open No. 2003-254155 (Patent Document 4) forms a film made of polyamideimide or polyimide containing at least one of molybdenum disulfide, graphite, and PTFE at a portion where the side rail contacts the ring groove side surface. A combined oil ring is disclosed.

  Japanese Patent Application Laid-Open No. 2002-310299 describes that the thickness of the synthetic resin film is preferably 1 to 10 μm. In JP-A No. 2003-254155, a resin film having a thickness of 10 μm is formed in Examples. In the three-piece type oil ring, the combined nominal width h1 is increased by at least twice the thickness of the film, so it is necessary to increase the axial width d1 of the piston groove width. Therefore, when the resin film is worn, the side clearance becomes large, and oil consumption increases or groove wear occurs.

  Japanese Patent Application Laid-Open No. 2000-27955 (Patent Document 4) discloses an oil ring in which a thin film is formed by applying and baking a solution containing a fluoroalkyl group-substituted alkoxide. This oil ring is excellent in the peelability of deposits such as carbon. However, since the film forming method is limited to a film forming method in which a solution is applied, the film thickness is likely to vary due to liquid pooling, and in particular, the surface of the base material having a complicated shape with a vertical waveform like the spacer expander of the present invention. It is difficult to form a uniform thin film throughout. Also, as the film thickness increases, it is necessary to increase the axial width of the piston groove width as in the case of the above-described invention technique. When the resin film is worn, the side clearance increases, oil consumption increases, and groove wear occurs. There is a high possibility of doing.

Although not shown, the outermost surface of the spacer expander of the present invention is coated with a fluorine resin film.
Oil sludge is particularly likely to adhere / deposit in the space 52 between the flat recesses between the ears and protrusions of the spacer expander and the side rails. Therefore, an oil sludge adhesion preventing effect can be obtained by forming a fluorine-based organic thin film on at least the upper and lower surfaces of the spacer expander or on the surface of the side rail facing the spacer expander. More preferably, the fluorine-based organic thin film is provided on both the surface of the side rail facing the spacer expander and the upper and lower surfaces of the spacer expander. The fluorine-based organic compound for forming the fluorine-based resin film is not particularly limited as long as it is a compound having a hydrocarbon group which is at least partially substituted with fluorine and has a certain vapor pressure. When the fluorinated organic compound contains a CF3 group and / or a CF2 group, a high oil sludge adhesion / deposition prevention function or sticking prevention function can be obtained.

  In consideration of adhesion to the Ni plating film or the nitride layer, a compound containing a metal such as a fluorinated organometallic compound is preferable. Since these compounds undergo a dehydration reaction or a dehydrochlorination reaction with a hydroxyl group present on the surface of the substrate or the adhesion layer formed on the substrate to form a siloxane bond or a metal-oxygen bond, a strong adhesion can be realized.

  Accordingly, examples of the fluorinated organometallic compound include a fluoroalkyl group-substituted metal alkoxide in which a part of the alkoxy group is substituted with a fluoroalkyl group, and a metal halide having a fluoroalkyl group. In view of cost and ease of handling, the fluorinated organometallic compound is preferably a fluorinated alkylsilane. Examples of the fluorinated alkylsilane include CF3 (CF2) 7C2H4Si (OCH3) 3, CF3 (CF2) 7C2H4Si (OC2H5) 3, CF3 (CF2) 5C2H4SiCl3, CF3 (CF2) 7C2H4SiCl3, CF3CH2O (CH2) 15SiCl3. In particular, CF3 (CF2) 7C2H4Si (OCH3) 3 and CF3 (CF2) 7C2H4Si (OC2H5) 3 are more preferable because they do not generate HCl even when they react with hydroxyl groups on the substrate.

  The thickness of the fluorine-based organic thin film is preferably 0.1 μm or less. The formed thin film composed of a fluorine-based organic compound layer is a dense thin film with fluoroalkyl groups regularly arranged on the surface, and has a high oil sludge adhesion prevention function or anti-adhesion function, and an excellent oil over a long period of time. The control function can be maintained. In particular, when the fluorinated organic compound thin film is substantially composed of a monomolecular layer of a fluorinated organic compound, the fluoroalkyl group is very densely present on the outermost layer, so that a more excellent effect can be obtained.

  Further, an adhesion layer may be provided between the substrate and the fluorinated organic thin film. Examples of the adhesion layer include a SiOx (X = 1, 2) layer and other metal oxide layers, but a material having excellent adhesion to the substrate is preferable. Since these oxide layers have hydroxyl groups on the surface, when a fluoroalkylsilane or a fluorine-based organic metal compound is used in the step of coating the fluorine-based organic thin film, which will be described later, the fluorine-based organic thin film is a siloxane bond or a metal. -It bonds firmly through an oxygen bond. For this reason, even if it is used for a long period of time, the fluorine-based organic thin film does not peel off and exhibits an excellent adhesion or adhesion preventing effect.

  In the adhesion layer using a metal alkoxide, since many hydroxyl groups exist on the surface, particularly excellent adhesion can be obtained. As the metal alkoxide, it is preferable to use a metal alkoxide selected from the group consisting of Si, Al, Ga, V, W, and Ta. Specifically, Si (OC2H5) 4, Al (OC2H5) 3, Al (OC3H7) 3, Al (OC4H9) 3, Ga (OC2H5) 3, VO (OC2H5) 3, W (OC2H5) 6, Ta (OC3H7 ) 5 etc.

  Moreover, in the adhesion layer using a metal alkoxide, an alkyl group remains in the adhesion layer and imparts toughness. Therefore, the influence of stress is alleviated, and it is effective in preventing crack generation and film peeling. In this case, the alkyl group is preferably a short chain so as not to hinder the subsequent binding reaction between the fluorinated organic thin film and the adhesion layer, such as dimethyldiethoxylane, methyltrimethoxysilane, and methyltriethoxysilane. preferable. In particular, dimethyldiethoxylane is effective because it can form a film by a chain reaction, control the film thickness, and increase the strength of the entire film. Moreover, you may use a silane coupling agent, a titanate coupling agent, an organic chromium coupling agent, etc. The total thickness of the adhesion layer and the fluorinated organic thin film is preferably less than 1 μm, more preferably 0.5 μm or less, and particularly preferably 0.3 μm or less. If the thickness is 1 μm or more, the combined tension may increase, which is not preferable from the viewpoint of film formation time and material cost.

  A vapor phase method is used to form the fluorine-based organic thin film, and the raw material fluorine-based organic compound is vaporized and attached to the substrate. The gas phase method is simple and excellent in mass productivity, and can form a dense film with high adhesion even with a substrate having a complicated shape. The gas phase reaction is usually allowed to proceed by putting a member covering the film and a fluorinated organic compound as a raw material in a reaction vessel and heating to evaporate the fluorinated organic compound. A film can be formed under atmospheric pressure, but the inside of the container may be depressurized if necessary. The thickness of the fluorinated organic thin film can be adjusted to a desired value by appropriately setting the treatment time, the temperature in the container, the pressure in the container, the amount of the fluorinated organic compound to be put in the container, and the like.

  The fluorinated organic thin film may be formed immediately before finishing the outer peripheral sliding surface. Even when the finishing process is not performed after the thin film is formed, the thin film on the outer peripheral sliding surface is removed at the initial stage of operation because the fluorine-based organic thin film of the present case is extremely thin.

Japanese Utility Model Publication No. 4-64658 JP 2003-28299 A JP 2002-310299 A JP 2003-254155 A JP 2000-27955 A

This will be described below based on examples.
In order to confirm the effect of the three-piece combination oil ring of the present invention, it was prepared by the following process and confirmed by engine experiments.
1. Ni plating on wire rod While rolling at a speed of 1 m / min on a rolled strip (SUS304 material) for spacer expander with a width of 2.5mm and a thickness of 0.3mm, using a wire rod plating device. Ni plating was performed. The obtained plating thickness was about 5 μm. In the subsequent process, a process of forming a corrugated shape by gear molding and forming an ear portion by shearing the base material is included, so there is a concern about prevention of peeling of the plating film. Was used. The plating conditions are as follows. After the completion of plating, the plating film thickness and hardness were measured.
The results are as follows.
Ni plating film thickness: 4-5 μm
Hardness: Hv378

2. Plastic processing The wire is formed into a wave shape in the vertical direction by gear forming → The ear is formed by shearing in the vertical direction at one end of the wire → The ring is formed so that the ear is on the inner peripheral side → Nitriding → Cutting A spacer expander was formed.
The three-piece combination oil ring using the created spacer expander has a ring nominal diameter of 75 mm and a combined nominal width h1 of 2.5 mm or 3.5 mm.
Combination thickness: 2.5 mm.

3. Nitriding treatment After degreasing and cleaning, gas nitriding was performed at 550 ° C. in an atmosphere of NH 390% and N 210% for 30 minutes. For the nitriding treatment, a furnace having a muffle structure was used, and the temperature was raised after the furnace was once brought into a true state. Prior to the nitriding treatment, a predetermined amount of ammonium chloride was first added at a predetermined timing to reduce the passive film. After the nitriding treatment, qualitative analysis was performed to identify the phase constituting the nitride layer by observing the depth of the nitride layer at the ear and measuring the hardness and X-ray diffraction. X-ray diffraction was performed with Cu-Kα rays, a tube voltage of 40 kV, and a tube current of 30 mA.
The results are as follows.
・ Nitriding depth: 19μm (Hv700 or more)
-Surface hardness of nitride layer: Hv1220
Nitride phase: (Fe, Cr, Ni,...) 4N phase: 45 to 53% (compound phase having peaks at 2θ = 40 ° and 2θ = 46 ° in Cu-Kα X-ray diffraction)

4). Formation of fluorinated organic thin films
(a) Pretreatment In order to improve the adhesion of the fluorinated organic thin film, the spacer expander was sufficiently washed in advance to remove surface contamination. Fluorinated alkylsilane was used as the fluorine-based organic compound. In order to chemically bond the substrate and the film, it is desirable that a hydroxyl group exist on the substrate surface. Therefore, in order to increase the hydroxyl group on the substrate surface, the substrate surface was previously immersed in an aqueous NaOH solution.
In order to improve the adhesion between the spacer expander substrate and the fluorinated organic thin film, an adhesion layer may be provided between the layers. In that case, since the metal oxide layer such as SiOx (X = 1, 2) layer has a hydroxyl group on the surface as the adhesion layer, fluorinated alkylsilane or fluorinated organic is used in the step of coating the fluorinated organic thin film. When a metal compound or the like is used, the fluorine-based organic thin film is firmly bonded through a siloxane bond or a metal-oxygen bond. However, the spacer expander of the present application has an effect that a thin oxide layer is formed on the surface of the Ni plating film by nitriding treatment and the adhesion is strong.

(b) Formation of fluorinated organic thin film In the three-piece combination oil ring of the embodiment of the present invention, the resin film is coated on the entire surface of the spacer expander or the entire surface of the side rail. However, it is not necessary for the entire surface, and at least the concave portion of the spacer expander that contacts the engine oil and the surface of the side rail facing the spacer expander require a resin film.
After washing the spacer expander and side rail in acetone, in the presence of heptadecafluoro-1,1,2,2-tetrahydro-decyl-trietoxysilane, while controlling the container temperature to be 190 ° C. in a sealed container For 60 minutes to form a thin film. Note that the inside of the sealed container was not replaced with gas and was in an air atmosphere, and neither pressurization nor depressurization was performed. A three-piece oil ring was produced by combining the obtained side rail and spacer expander.

  A part of each of the spacer expander and the side rail was cut, and the surface of each part was analyzed by XPS. From XPS analysis, it was confirmed that peaks attributed to the CF3 group and the CF2 group were formed, and it was found that a very thin film containing a fluoro group was formed.

6). Engine test A three-piece combined oil ring was tested with an engine. The engine used for the test was a 4-cylinder 1.5L gasoline engine. Before each oil ring of Example 1 and Comparative Examples 1 to 3 is incorporated in the piston, the weight of each oil ring is measured, and a pressure ring of a common specification is incorporated in each cylinder, and Example 1 is compared with each of 1-4 cylinders. The oil rings of Examples 1, 2, and 3 were incorporated.

Example 1
・ 3-piece combination oil ring ・ Nominal diameter: 75 mm, thickness: 2.5 mm, width: 2.5 mm
・ Combination tension 12N
Spacer expander
Base material: Austenitic stainless steel (SUS304)
Thickness: 0.3mm
Surface treatment Ear shear surface-gas nitriding (nitridation depth 12μm)
Other surface-Ni plating (thickness 4.5μm)
Outer surface-heptadecafluoro-1,1,2,2-tetrahydro-decyl-trietoxysilane film (thickness approximately 0.07μm)
side rail
Base material: 17Cr martensite stainless steel
Surface treatment Peripheral surface-Gas nitriding diffusion layer
Side-inner peripheral nitride layer
Outer surface-heptadecafluoro-1,1,2,2-tetrahydro-decyl-trietoxysilane film (thickness approximately 0.08μm)

Comparative Example 1
・ 3-piece combination oil ring ・ Nominal diameter: 75 mm, thickness: 2.8 mm, width: 3.5 mm
・ Combination tension 13N
Spacer expander
Base material: Austenitic stainless steel (SUS304)
Thickness: 0.3mm
Surface treatment Ear shear surface-gas nitriding (nitridation depth 10μm, uneven)
Other surface-gas nitriding (nitridation depth 12μm)
Outer surface-heptadecafluoro-1,1,2,2-tetrahydro-decyl-trietoxysilane film (thickness approximately 0.08μm)
side rail
Base material: 17Cr martensite stainless steel
Surface treatment: outer peripheral surface-gas nitriding diffusion layer
Outer surface heptadecafluoro-1,1,2,2-tetrahydro-decyl-trietoxysilane film (thickness approx. 0.07μm)

Comparative Example 2
・ 3-piece combination oil ring ・ Nominal diameter: 75 mm, thickness: 2.5 mm, width: 2.5 mm
・ Combination tension 12N
Spacer expander
Base material: Austenitic stainless steel (SUS304)
Thickness: 0.3mm
Surface treatment Ear shear surface-gas nitriding (nitriding depth 12)
Other surface-Ni plating (thickness 4.5μm)
Outer surface-heptadecafluoro-1,1,2,2-tetrahydro-decyl-trietoxysilane film (thickness approximately 0.08μm)
side rail
Base material: 17Cr martensite stainless steel
Surface treatment Peripheral surface-Gas nitriding diffusion layer
Side surface / inner peripheral surface-nitride layer
Outer surface-heptadecafluoro-1,1,2,2-tetrahydro-decyl-trietoxysilane film (thickness approx. 0.08 μm)

Comparative Example 3
・ 3-piece combination oil ring ・ Nominal diameter: 75 mm, thickness: 2.5 mm, width: 2.5 mm
・ Combination tension 27N
Spacer expander
Base material: Austenitic stainless steel (SUS304)
Thickness: 0.3mm
Surface treatment Ear shear surface-gas nitriding (nitridation depth 10μm, uneven)
Other surface-Ni plating (thickness 4.5μm)
No external surface
side rail
Base material: 17Cr martensite stainless steel
Surface treatment Peripheral surface-Gas nitriding diffusion layer
Side surface / inner peripheral surface-nitride layer
Outer surface-None

* The pressure ring with the same specifications was used.

Table 1: Oil rings used in engine experiments

Sludge accumulation engine test The engine oil used was a market-recovered deteriorated oil, and a cyclic operation was repeated in which the operating conditions from the stopped state to the maximum output speed and the oil / water temperature conditions from low to high were repeated continuously. After a predetermined time, the piston was taken out and a small force was applied to the oil ring incorporated in each cylinder, and the oil ring was removed from the piston. Thereafter, the oil ring was further immersed in acetone and subjected to ultrasonic cleaning for a certain period of time, so that only the amount of deposits adhered firmly remained in the oil ring. Thereafter, the weight of each oil ring was measured, and the amount of change from the weight before the test was regarded as the amount of deposit and compared. The amount of deposits is shown in the table with Example 1 as the reference 100.
Table 2: Sludge accumulation engine test results

Oil consumption test The engine used for the test was a gasoline engine with a 4-cylinder displacement of 2.0L. First, an oil ring and a compression ring of Example 1 were incorporated in all the cylinders 1 to 4 and tested. The amount of oil to be used was measured before the engine was operated, the engine was operated for a predetermined time under a full load of 6000 rpm, and the oil consumption before and after the test was measured. The oil consumption per unit time was calculated by dividing the value by the operating time.
Thereafter, tests were similarly performed in the order of Comparative Examples 1, 2, and 3 on the same engine.
The results are shown in FIG.

Frictional force measurement test Using a piston ring frictional force measuring device (Fig. 3) that made it possible to incorporate only an oil ring, the piston was moved up and down in the cylinder, and the load sensor output at that time was measured.
The oil rings of Example 1 and Comparative Examples 1, 2, and 3 were assembled in order, and the maximum loads during piston reciprocation were compared. The results are shown in FIG.

Result Three-piece combination oil ring incorporating the spacer expander of the present invention is
1. The oil sludge accumulation amount is slightly larger than Comparative Example 2 where the combined thickness is large (the cross section area of the oil passage groove of the spacer expander is large), but the result is less than other Comparative Examples due to the effect of FAS. .
2. The engine oil consumption is small and good in comparison with Comparative Example 23, which is a conventional specification with high tension.
3. The engine friction force is almost the same as that of the comparative example 2 other than the comparative example 2 with high tension.
As described above, the three-piece combined oil ring using the spacer expander according to the present invention has excellent effects of low oil consumption, less oil sludge accumulation, and less frictional force. Contributes to engine environmental measures.

The combination oil ring of the 1st invention of this application is shown. The oil consumption test result of the combination oil ring of this invention with a real machine engine and the comparison combination oil ring is shown. Schematic of test equipment for measuring friction force of combined oil ring It is a graph which shows the frictional force measurement result of the combination oil ring of this invention, and the comparison combination oil ring. The structure of an engine piston ring is shown. Cross section of axially corrugated 3-piece oil ring Schematic of axially corrugated 3-piece combination oil ring Cross section and schematic diagram of three-piece combined oil ring with radial corrugation

Explanation of symbols

10 Piston 231 Side rail 232 Spacer expander 50 Ear part 50a Nitrided layer 50b Nickel plated layer

Claims (3)

The spacer expander and a pair of side rails supported by the spacer expander is a three-piece combination oil ring having a width h1 of 1 to 3 mm. The spacer expander is formed in a piston axial waveform by a flat metal. The inner peripheral portion has a pressing piece that protrudes in the piston axial direction by shearing of the base material and presses the side rail radially outward. A nitride layer is formed, and the surfaces other than the nitrided shear surface are covered with a Ni plating film, and at least the outermost surface of the spacer expander facing the side rail and / or the spacer of the side rail A three-piece combined oil-retaining film characterized in that a thin film made of only a fluorine-based organic material is formed on the surface facing the expander. Grayed. The three-piece combined oil ring according to claim 1, wherein the combined tension is 5 to 15N. The three-piece combined oil ring according to claim 1, wherein the fluorine-based organic thin film includes a CF3 group and / or a CF2 group.

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