WO2019167241A1 - Piston ring - Google Patents

Piston ring Download PDF

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Publication number
WO2019167241A1
WO2019167241A1 PCT/JP2018/007892 JP2018007892W WO2019167241A1 WO 2019167241 A1 WO2019167241 A1 WO 2019167241A1 JP 2018007892 W JP2018007892 W JP 2018007892W WO 2019167241 A1 WO2019167241 A1 WO 2019167241A1
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WO
WIPO (PCT)
Prior art keywords
piston ring
groove
sliding surface
outer peripheral
along
Prior art date
Application number
PCT/JP2018/007892
Other languages
French (fr)
Japanese (ja)
Inventor
大志 清水
朋孝 大出
Original Assignee
株式会社リケン
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Publication date
Application filed by 株式会社リケン filed Critical 株式会社リケン
Priority to PCT/JP2018/007892 priority Critical patent/WO2019167241A1/en
Publication of WO2019167241A1 publication Critical patent/WO2019167241A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J9/00—Piston-rings, e.g. non-metallic piston-rings, seats therefor; Ring sealings of similar construction
    • F16J9/12—Details
    • F16J9/20—Rings with special cross-section; Oil-scraping rings

Definitions

  • the present invention relates to a piston ring for an internal combustion engine, and more particularly to a piston ring with improved lubrication characteristics due to the surface fine structure of the outer peripheral sliding surface.
  • the piston ring used as a functional part of an internal combustion engine (hereinafter also simply referred to as “ring”) is mainly required to have three functions: a gas seal function, a heat transfer function, and an oil control function.
  • a gas seal function that is, to seal the gap between the outer periphery of the piston and the inner wall of the cylinder so that the engine maintains a predetermined compression pressure
  • the ring has a self-tension to push the inner wall of the cylinder vertically.
  • the ring shape is determined, and the ring circumferential length is determined so as to minimize the abutment gap of the abutment portion required when the ring is set on the piston.
  • the ring is made of metal material to ensure the heat transfer function that transfers the heat of the piston top due to the high temperature and high pressure combustion gas to the cooled cylinder wall, and the outer periphery of the ring to ensure the oil control function
  • the surface shape is defined.
  • the top ring (the ring that is mounted on the most combustion chamber side of the piston, also referred to as “first pressure ring”)
  • first pressure ring the barrel face shape with excellent oil film lubrication function
  • second ring also called the “second pressure ring” which is attached to the crank chamber side rather than the top ring
  • a shape that improves the oil scraping performance by making the edge of the outer peripheral lower end as sharp as possible is adopted.
  • the surface pressure per unit area is increased and the oil scraping is performed. Designed to further improve performance.
  • the ring tension can be optimized. If the ring tension is too high, the gas seal characteristics and oil consumption are improved in the top ring and oil ring, but when the ring slides on the inner wall of the cylinder, the frictional force increases and the fuel consumption deteriorates. Further, the oil is excessively scraped and the lubricity is lowered. In the worst case, the ring and the cylinder are seized. On the other hand, if the ring tension is too low, the gas seal characteristics are lowered, the combustion gas is blown out, the output is lowered, the oil scraping performance is lowered, and the oil consumption is increased.
  • a concave portion that functions as an oil reservoir and improves lubricity is formed on a peripheral sliding surface with a pulse laser, and the concave portion has a diameter of 100 to 300 ⁇ m and a depth of 100 ⁇ m or more.
  • a piston ring having an area ratio of 5 to 50% is set to 100 ⁇ m or more so that the concave portion does not disappear even with the progress of wear.
  • Patent Document 2 also discloses a piston ring that does not lower the gas seal and oil seal functions in addition to reducing friction.
  • Patent Document 2 pays attention to a non-recessed region where no recess is formed, and the area ratio of the non-recessed region to the barrel width region is 20 to 85%, and the non-recessed region is present on all axial cut surfaces. Teaches that it needs to exist.
  • the Example which made the opening width of a recessed part 0.19 mm x 0.16 mm and the depth 10 micrometers is disclosed.
  • Patent Document 3 a large number of dimples formed on the outer peripheral sliding surface are formed to have a plurality of depths, and a plurality of types of dimples having different depths are alternately arranged in the circumferential direction of the piston ring. Disposed piston rings are disclosed. Specifically, three types of dimples having a diameter of about 100 ⁇ m and a depth of 4 to 5 ⁇ m, 2 to 3 ⁇ m, and 1 to 1.5 ⁇ m are disclosed.
  • Patent Document 4 as a method of forming a plurality of recesses in a piston ring coated with a hard coating, an oil pool is obtained by shot peening the piston ring base material before coating the hard coating and then coating the hard coating. It is disclosed that the fine dimples that act as an anti-wear can be formed on the outer peripheral sliding surface after the hard coating is coated. It is also disclosed that the fine dimple is a concave portion having a diameter of 0.1 to 5 ⁇ m with a substantially arc-shaped cross section.
  • An object of the present invention is to provide a piston ring that exhibits excellent lubrication characteristics by reducing the frictional force between the ring and the inner wall of the cylinder while maintaining excellent gas seal characteristics and oil consumption characteristics.
  • Non-Patent Document 1 the pressure distribution generated in the lubricating oil between the outer peripheral sliding surface 202 of the piston ring 201 and the cylinder inner wall 203 when the barrel face shaped piston ring 201 slides is shown in FIG. Is disclosed. That is, the lubricating oil is compressed in the traveling direction X side of the piston ring 201 in the outer peripheral sliding surface 202, and the generated compressive force cancels the ring tension, thereby reducing the frictional force.
  • the piston ring of the present invention is a piston ring in which a concave portion is formed on an outer peripheral sliding surface, and the concave portion has a deepest portion having the smallest outer diameter and an inclined portion that gradually decreases in diameter toward the deepest portion. It is characterized by having.
  • the inclined portion is continuous with the deepest portion.
  • the inclined portion includes a curved portion that is convex.
  • the concave portion further has a top portion having an outer diameter larger than that of the surroundings, and the inclined portion gradually increases in diameter toward the top portion.
  • the piston ring of the present invention it is preferable that a plurality of the recesses are formed, and the plurality of recesses include two or more recesses having different outer diameters of the deepest part.
  • the concave portion is a groove portion extending along a predetermined direction.
  • the groove portion extends along the circumferential direction.
  • a plurality of the groove portions are formed, and the plurality of groove portions are arranged along the circumferential direction.
  • the groove portion further has an axially extending portion that extends in the axial direction from the periphery.
  • the concave portion does not reach the abutment portion.
  • a hard coating for covering the outer peripheral sliding surface is provided.
  • FIG. 3A shows a state before the outer peripheral sliding surface is worn
  • FIG. 3B shows a state after the outer peripheral sliding surface is worn.
  • sectional drawing shows the other example of the groove part formed in the outer periphery sliding surface of the piston ring shown in FIG.
  • sectional drawing shows the further another example of the groove part formed in the outer peripheral sliding surface of the piston ring shown in FIG.
  • FIG. 1 It is a side view which shows the further another example of the groove part formed in the outer periphery sliding surface of the piston ring shown in FIG. It is a figure which shows a mode that a groove part is formed in the outer peripheral sliding surface of a piston ring. It is a side view which shows an example of the groove part formed in the outer periphery sliding surface of the piston ring of FIG. It is sectional drawing which follows an axial direction which shows an example of the groove part formed in the outer peripheral sliding surface of the piston ring of FIG. It is a figure which shows the pressure distribution of the compressive force which generate
  • FIG. 1 is a plan view of a piston ring 1 as an embodiment of the present invention.
  • the piston ring 1 is formed in a barrel face shape, and is used by being mounted as a top ring (first pressure ring) on a piston of an engine (internal combustion engine) such as an automobile. Further, the piston ring 1 is formed in a split ring shape provided with the joint portion 20.
  • the outer surface of the piston ring 1 constitutes an outer peripheral sliding surface 10 that slides with the cylinder inner wall.
  • the central axis of the piston ring 1 is O
  • the circumferential direction along the outer peripheral sliding surface 10 of the piston ring 1 is A
  • the axial direction along the central axis O is B.
  • the piston ring 1 slides along the axial direction B with the cylinder inner wall.
  • FIG. 2 is a side view showing the configuration of the outer peripheral sliding surface 10 of the piston ring 1.
  • the outer peripheral sliding surface 10 of the piston ring 1 is formed with a plurality of groove portions 100 that are concave portions as fine structures.
  • the groove portions 100 respectively extend along the circumferential direction A, and the plurality of groove portions 100 are arranged along the circumferential direction A and the axial direction B (direction along the central axis O of the piston ring 1).
  • the total area ratio of the plurality of groove portions 100 formed on the outer peripheral sliding surface 10 of the piston ring 1 is preferably 20% or more and 80% or less with respect to the area of the outer peripheral sliding surface 10.
  • FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2.
  • FIG. 3 (a) is before the outer peripheral sliding surface 10 is worn
  • FIG. 3 (b) is after the outer peripheral sliding surface 10 is worn.
  • the groove portion 100 has a deepest portion 110 having the smallest outer diameter or radius from the central axis O, and a radius from the outer diameter or the central axis gradually decreases toward the deepest portion 110.
  • an inclined portion 120 extends along the axial direction B.
  • the inclined portion 120 is continuously arranged with the deepest portion 110 on both sides along the axial direction B of the deepest portion 110. In other words, the inclined portion 120 is disposed adjacent to the deepest portion 110.
  • Lubricating oil is held in the groove portion 100.
  • the deepest part 110 extends a predetermined length along the axial direction B, the deepest part 110 is formed only at one point in the axial direction B and does not extend the predetermined length along the axial direction B. Compared to the above, more lubricating oil can be retained.
  • the piston ring 1 slides along the sliding direction (axial direction B)
  • the lubricating oil held in the deepest portion 110 of the groove 100 is pushed out to the inclined portion 120 along the axial direction B.
  • the cross-sectional shape along the circumferential direction A of the groove portion 100 of the piston ring 1 may form a cross-sectional shape of the groove portion 100 as shown in FIG.
  • the cross-sectional shape of the groove 100 shown in FIG. 3A may be formed along the circumferential direction A and the axial direction B.
  • the above-mentioned effect obtained by forming the cross-sectional shape of the groove part 100 shown in FIG. 3A along the axial direction B and the above-described effect obtained by forming along the circumferential direction A Can be obtained together.
  • the inclined part 120 of the groove part 100 includes a curved part 121 having a convex shape.
  • the bending portion 121 has a steep slope at a position continuous with the deepest portion 110, and gradually slopes gradually away from the deepest portion 110.
  • the inclined portion 120 includes the curved portion 121, the lubricating oil pushed out from the deepest portion 110 is rapidly compressed, so that the above-described squeeze effect can be exhibited remarkably.
  • the cross-sectional shape of the groove 100 shown in FIG. 3A is formed along the axial direction B, a dynamic pressure effect is obtained by the curved portion 121.
  • the 3A is formed along the circumferential direction A, the lubricating oil retained in the groove 100 when the piston speed of the piston ring 1 becomes zero.
  • the lubricating oil from which the lubricating oil is squeezed out along the circumferential direction A from the groove portion 100 due to the squeeze effect is more easily squeezed out along the circumferential direction A by the curved portion 121.
  • the frictional force can be reduced.
  • the depth D from the outer peripheral sliding surface 10 in the deepest part 110 of the groove part 100 is preferably 1 ⁇ m or less, and more preferably 0.2 ⁇ m or less.
  • the width W along the axial direction B of the groove part 100 is preferably 0.3 mm or less, and more preferably 0.1 mm or less.
  • the outer peripheral sliding surface 10 before wear is indicated by a broken line.
  • the groove 100 has the deepest portion 110 in the same manner as before the wear even when the outer peripheral sliding surface 10 is worn by the piston ring 1 repeatedly sliding with the cylinder inner wall. Since it has the inclined part 120, the same effect as before the abrasion described above can be obtained.
  • the configuration of the piston ring 1 before the outer peripheral sliding surface 10 is worn will be described.
  • FIG. 4 is a cross-sectional view showing another example of the groove portion 100 formed on the outer peripheral sliding surface 10 of the piston ring 1.
  • Each of the cross sections shown in FIGS. 4A to 4F is a predetermined cross-sectional view orthogonal to the outer peripheral sliding surface 10.
  • examples of the predetermined cross-sectional view orthogonal to the outer peripheral sliding surface 10 include a cross-sectional view along the circumferential direction A and a cross-sectional view along the axial direction B.
  • FIG. 4 (a) to FIG. f) illustrates a cross-sectional view along the circumferential direction A (same as a cross-sectional view orthogonal to the axial direction B).
  • the cross-sectional shape of the groove portion 100 shown in FIG. 4A is shown in FIG. 3A except that the deepest portion 110 is formed at one point in the circumferential direction A and does not extend along the circumferential direction A. This is the same as the cross-sectional shape.
  • the groove portion 100 having the cross-sectional shape shown in FIG. 3A is more suitable for the groove portion 100 shown in FIG. 3A in that a lot of lubricating oil can be held in the deepest portion 110 extending along the circumferential direction A. It is more preferable than the groove part 100 which has the cross-sectional shape shown to (a).
  • the cross-sectional shape of the groove portion 100 shown in FIG. 4B is the cross-sectional shape shown in FIG. 4A except that the inclined portion 120 is disposed only on one side along the circumferential direction A of the deepest portion 110. It is the same. 4 (a) and 4 (b) show a cross-sectional view along the circumferential direction A as a predetermined cross-sectional view orthogonal to the outer peripheral sliding surface 10, but FIG. 4 (a) and FIG. When (b) is a sectional view along the axial direction B, when the piston ring 1 slides in one direction along the axial direction B in the groove portion 100 having the sectional shape shown in FIG.
  • the groove part 100 having the cross-sectional shape shown in FIG. 4A can obtain a higher squeeze effect than the groove part 100 having the cross-sectional shape shown in FIG.
  • FIG. 4C shows an example in which the groove portions 100 having the cross-sectional shape shown in FIG. 4B are arranged so that the deepest portions 110 are adjacent to each other.
  • the groove portion 100 having the cross-sectional shape of FIG. 4B is arranged as shown in FIG. 4C, so that when the cross-sectional view of FIG. Regardless of the sliding direction, a substantially constant squeeze effect can be obtained regardless of the sliding direction.
  • the groove portion 100 having the cross-sectional shape shown in FIG. 4D includes the deepest portion 110 and the inclined portion 120 that is arranged continuously to the deepest portion 110 and gradually decreases in diameter toward the deepest portion 110.
  • the top portion 130 has a larger diameter or radius than the surroundings, and the inclined portion 120 gradually increases in diameter toward the top portion 130. Since the top 130 has an outer diameter or radius smaller than that of the outer peripheral sliding surface 10, it does not contact the cylinder inner wall.
  • the inclined portion 120 shown in FIG. 4D is configured by a convex curved portion 121.
  • FIG. 4E shows an example in which the groove portions 100 having the cross-sectional shape shown in FIG. 4B are arranged so that the inclined portions 120 are adjacent to each other.
  • FIG. 4F shows a groove portion 100 having the cross-sectional shape shown in FIG.
  • a diameter-reduced portion 123 that is reduced in diameter toward the top portion 130 via the step surface 122 is formed at the boundary of each inclined portion 120.
  • each inclined portion 120 is configured by a convex curved portion 121. In this way, by connecting a plurality of inclined portions 120 via the step surface 122 with respect to the sliding direction, a further narrowing effect can be obtained.
  • FIG. 5 is a cross-sectional view showing still another example of the groove portion 100 formed on the outer peripheral sliding surface 10 of the piston ring 1.
  • the inclined part 120 does not include the curved part 121 and may be formed in a substantially linear shape.
  • the groove part 100 may have the some inclination part 120 arrange
  • the inclination angle of the substantially linear inclined portion 120 is preferably not less than 0.2 ° and not more than 2 °, and more preferably not less than 0.2 ° and not more than 0.5 °.
  • FIG. 5 shows a cross-sectional view along the circumferential direction A (same as a cross-sectional view orthogonal to the axial direction B) as a predetermined cross-sectional view orthogonal to the outer peripheral sliding surface 10. It is good also as a sectional view along.
  • FIG. 6 is a cross-sectional view showing an example of the relationship of the deepest part 110 of the groove part 100 formed on the outer peripheral sliding surface 10 of the piston ring 1.
  • the cross-sectional shape of the groove portion 100 shown in FIG. 6 is simplified for explaining the depths D1 to D3 from the outer peripheral sliding surface 10 of the deepest portion 110.
  • a plurality of groove portions 100 may be formed in a predetermined cross-sectional view orthogonal to the outer peripheral sliding surface 10.
  • the plurality of groove portions 100 formed in a predetermined cross-sectional view do not communicate at any position in the circumferential direction A and any position in the axial direction B. That is, the three groove parts 100 shown in FIG. 6 are separate structures that are not in communication with each other.
  • the depths D1 to D3 of the deepest portions 110 of the three groove portions 100 are different from each other. That is, the plurality of formed groove portions 100 may include two or more groove portions 100 having different outer diameters or radii of the deepest portion 110.
  • FIG. 7 is a side view showing another example of the groove portion 100 formed on the outer peripheral sliding surface 10 of the piston ring 1.
  • the plurality of grooves 100 formed on the outer peripheral sliding surface 10 of the piston ring 1 may be arranged in a staggered manner along the axial direction B. Even if it arrange
  • the groove portion 100 may be formed such that the width along the axial direction B decreases as it goes toward both ends along the circumferential direction A.
  • the shape of the groove portion 100 in a side view is, for example, a shape in which the outer diameters at both ends in the circumferential direction A of the deepest portion 110 gradually increase as shown in FIG. 3A and FIG. By combining with squeeze effect can be further enhanced.
  • the width along the axial direction B of the groove portion 100 shown in FIG. 7B is more than 0.2 mm at the central portion along the circumferential direction A, and is 0.2 mm or less at both ends along the circumferential direction A. preferable.
  • FIG. 8 and 9 are side views showing still another example of the groove portion 100 formed on the outer peripheral sliding surface 10 of the piston ring 1.
  • the groove 100 may continuously extend linearly along the circumferential direction A.
  • the groove portion 100 includes an axially extending portion 140 that extends continuously in the circumferential direction A but extends in the axial direction B from the periphery. Alternatively, it may be formed in a zigzag shape.
  • the groove part 100 has the axially extending part 140, when the piston ring 1 slides along the axial direction B with respect to the inner wall of the cylinder, the lubricating oil held in the groove part 100 is axially driven by inertial force. Concentrate on the direction extension 140. As a result, the lubricating oil is compressed by the axially extending portion 140, and a squeeze effect is likely to be manifested by an increase in pressure.
  • a plurality of grooves 100 arranged in a zigzag shape along the circumferential direction A may be formed so that the grooves 100 shown in FIG. 8B are divided. .
  • Each groove 100 shown in FIG. 8C has an axially extending portion 140.
  • the groove portion 100 shown in FIG. 8C is preferable to the groove portion 100 shown in FIG. 8B in that the dispersion of the flow of the lubricating oil in the circumferential direction A can be suppressed.
  • the V-shaped groove portion 100 may be disposed along the circumferential direction A.
  • the groove portion 100 shown in FIG. 8D has axially extending portions 140 at both ends along the axial direction B.
  • the groove portion 100 may have the axially extending portions 140 at regular intervals while continuously extending linearly along the circumferential direction A. Further, as shown in FIG. 9B, a plurality of groove portions 100 arranged along the circumferential direction A may be formed so that the groove portion 100 shown in FIG. 9A is divided. Each groove portion 100 shown in FIG. 9B has an axially extending portion 140.
  • the groove part 100 shown in FIG. 9B is preferable to the groove part 100 shown in FIG. 9A in that the dispersion of the flow of the lubricating oil in the circumferential direction A can be suppressed.
  • FIG. 9 (c) is an enlarged view of the axially extending portion 140 of the groove portion 100 of FIGS. 9 (a) and 9 (b).
  • the axially extending portion 140 is gradually reduced in length along the circumferential direction A toward the tip, and more preferably curved in a concave shape.
  • FIG. 10 is a side view showing a configuration around the joint portion 20 of the piston ring 1. As shown in FIG. 10, it is preferable that the groove portion 100 does not reach the joint portion 20. Since the groove part 100 does not reach the joint part 20, it is preferable in that the lubricant retained in the groove part 100 can be prevented from leaking from the joint part 20. It is preferable that the distance C between the edge part of the groove part 100 and the abutment part 20 is 0.2 mm or more.
  • FIG. 11 is a side view showing still another example of the groove portion 100 formed on the outer peripheral sliding surface 10 of the piston ring 1.
  • the groove portion 100 may extend obliquely along the circumferential direction A and the axial direction B. In other words, it may be configured to extend so as to be inclined with respect to both the circumferential direction A and the axial direction B.
  • the groove part 100 mentioned above may be formed in the outer periphery sliding surface 10 of the piston ring 1 by arbitrary combinations.
  • the piston ring 1 may include a hard coating that covers the outer peripheral sliding surface 10.
  • the piston ring 1 is provided with a hard coating, so that the wear resistance is improved and the cross-sectional shape of the groove portion 100 can be further maintained.
  • the hard coating is formed as a hard coating layer that coats the outer peripheral sliding surface 10 in layers.
  • the hard film is preferably a hard film selected from a chromium plating film, an ion plating film, a nitride film, and a hard carbon film.
  • the thickness of the hard coating is preferably such that it does not fill the groove 100 and make it shallow.
  • the thickness of the hard film is preferably less than 60 ⁇ m, more preferably less than 45 ⁇ m, and even more preferably less than 30 ⁇ m in the case of an ion plating film.
  • the thickness of the diffusion layer having a Vickers hardness of 700 HV 0.1 or more is preferably 30 ⁇ m or more, more preferably 50 ⁇ m or more, and even more preferably 70 ⁇ m or more.
  • the chromium plating film the depth is hardly changed even if the film thickness is reduced in the depth direction due to the cancellation of the electric field in the groove portion 100 and the opening diameter is slightly reduced.
  • the thickness of the hard coating is preferably less than 80 ⁇ m, more preferably less than 60 ⁇ m, and even more preferably less than 40 ⁇ m in a gasoline vehicle piston ring.
  • the thickness of the hard coating is preferably less than 120 ⁇ m, more preferably less than 100 ⁇ m, and even more preferably less than 80 ⁇ m in a piston ring for diesel vehicles (particularly heavy duty).
  • it is preferably less than 350 ⁇ m, more preferably less than 325 ⁇ m, and further preferably less than 300 ⁇ m.
  • the groove portion 100 may be formed on the outer peripheral sliding surface 10 after the hard coating layer is formed, or the hard coating layer may be formed after the groove portion 100 is formed.
  • FIG. 12 is a diagram illustrating a state in which the groove portion 100 is formed on the outer peripheral sliding surface 10 of the piston ring 1.
  • FIGS. 13 and 14 are a side view and a cross-sectional view along the axial direction B showing an example of the groove 100 formed in the outer peripheral sliding surface 10 of the piston ring 1.
  • FIG. 12 in a state where a plurality of piston rings 1 are stacked (stacked) along the axial direction B, they are spiral along the circumferential direction A, that is, have a constant inclination with respect to the axial direction B.
  • the groove part 100 as shown, for example in FIG. 13A or 13B is formed on the outer peripheral sliding surface 10.
  • the manufacturing lead time is shortened, and the cost can be reduced.
  • the chamfered portions 11 along the circumferential direction A at both end portions along the axial direction B of the piston ring 1 before forming the groove portion 100 is preferably 0.3 mm or less, and more preferably 0.1 mm or less.
  • the depth D ′ of the deepest portion 110 of the groove portion 100 is preferably 1 ⁇ m or less, and more preferably 0.2 ⁇ m or less.
  • the piston ring 1 has been described as having a barrel face shape, but is not limited to the barrel face shape, and may be any other shape such as a plain shape or a tapered face shape.
  • the present invention relates to a piston ring for an internal combustion engine.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Pistons, Piston Rings, And Cylinders (AREA)

Abstract

A piston ring (1) is configured so that a recess (100) is formed in an outer sliding surface (10) and has: a deepest section (110) where the outer diameter of the recess (100) is smallest; and a sloped section (120) which has a diameter gradually decreasing toward the deepest section (110).

Description

ピストンリングpiston ring
　本発明は、内燃機関用のピストンリングに関し、特に、外周摺動面の表面微細構造により潤滑特性を改善したピストンリングに関する。 The present invention relates to a piston ring for an internal combustion engine, and more particularly to a piston ring with improved lubrication characteristics due to the surface fine structure of the outer peripheral sliding surface.
　内燃機関の機能部品として使用されているピストンリング（以下、単に「リング」ともいう。）には、主に、ガスシール機能、伝熱機能、オイルコントロール機能の三つの機能が要求される。ガスシール機能を確保するために、すなわち、ピストン外周とシリンダ内壁との隙間をシールしてエンジンが所定の圧縮圧を保つために、リングがシリンダ内壁を垂直に押すための自己張力をもつようにリング形状が定められ、また、リングをピストンにセットする際に必要な合口部の合口隙間を最小にするようにリング周長が定められている。さらに、高温高圧の燃焼ガスによるピストン頂部の熱量を冷却されたシリンダ壁に伝達する伝熱機能を確保するために、リングは金属材料で製造され、オイルコントロール機能を確保するために、リングの外周面形状が定められている。 The piston ring used as a functional part of an internal combustion engine (hereinafter also simply referred to as “ring”) is mainly required to have three functions: a gas seal function, a heat transfer function, and an oil control function. To ensure the gas sealing function, that is, to seal the gap between the outer periphery of the piston and the inner wall of the cylinder so that the engine maintains a predetermined compression pressure, the ring has a self-tension to push the inner wall of the cylinder vertically. The ring shape is determined, and the ring circumferential length is determined so as to minimize the abutment gap of the abutment portion required when the ring is set on the piston. In addition, the ring is made of metal material to ensure the heat transfer function that transfers the heat of the piston top due to the high temperature and high pressure combustion gas to the cooled cylinder wall, and the outer periphery of the ring to ensure the oil control function The surface shape is defined.
　ピストンリングの外周面形状に言及すれば、トップリング（ピストンの最も燃焼室側に装着されるリングで「第１圧力リング」ともいう。）は、外周面にリング軸に平行な断面において樽型の油膜潤滑機能に優れたバレルフェイス形状が採用されており、セカンドリング（トップリングよりもクランク室側に装着されるリングで「第２圧力リング」ともいう。）は、テーパーフェイス形状に加え、外周下面端のエッジをなるべくシャープにしてオイルの掻き下げ性能を向上させる形状が採用されている。また、オイルリング（ピストンの最もクランク室側に装着されるリング）においては、張力を大きくし、且つシリンダ内壁との接触面積を小さくすることにより、単位面積当たりの面圧を高くしてオイル掻き性能をさらに向上させるように設計されている。 Referring to the shape of the outer peripheral surface of the piston ring, the top ring (the ring that is mounted on the most combustion chamber side of the piston, also referred to as “first pressure ring”) The barrel face shape with excellent oil film lubrication function is adopted, and the second ring (also called the “second pressure ring”, which is attached to the crank chamber side rather than the top ring), in addition to the tapered face shape, A shape that improves the oil scraping performance by making the edge of the outer peripheral lower end as sharp as possible is adopted. Also, in the oil ring (ring attached to the crank chamber closest to the piston), by increasing the tension and reducing the contact area with the inner wall of the cylinder, the surface pressure per unit area is increased and the oil scraping is performed. Designed to further improve performance.
　近年、内燃機関では、オイル燃焼物による大気汚染等の環境問題やＣＯ２削減への対応のため、オイル消費の削減と燃費の改善が強く求められている。すなわち、ピストンリングには、上記の三つの機能の確保に加え、オイル消費特性及び燃費特性についてもさらなる向上が求められている。 In recent years, internal combustion engines are strongly required to reduce oil consumption and improve fuel efficiency in order to cope with environmental problems such as air pollution caused by oil combustion products and CO 2 reduction. That is, the piston ring is required to further improve the oil consumption characteristics and the fuel consumption characteristics in addition to ensuring the above three functions.
　上記三つの機能を確保しつつ、オイル消費特性と燃費特性も満足させる方法として、第１にリング張力の最適化が挙げられる。リング張力が高すぎると、トップリングやオイルリングではガスシール特性やオイル消費は改善するが、リングがシリンダ内壁を摺動するとき、摩擦力が増加し、燃費が悪化する。さらに、オイルを掻き過ぎることにより潤滑性が低下し、最悪の場合はリングとシリンダが焼付いてしまうことになる。また、逆に、リング張力が低すぎると、ガスシール特性が低下し、燃焼ガスの吹き抜けが生じて出力低下が生じるし、オイル掻き性能が低下し、オイル消費が増加することになる。 As a method of satisfying the oil consumption characteristics and fuel consumption characteristics while ensuring the above three functions, first, the ring tension can be optimized. If the ring tension is too high, the gas seal characteristics and oil consumption are improved in the top ring and oil ring, but when the ring slides on the inner wall of the cylinder, the frictional force increases and the fuel consumption deteriorates. Further, the oil is excessively scraped and the lubricity is lowered. In the worst case, the ring and the cylinder are seized. On the other hand, if the ring tension is too low, the gas seal characteristics are lowered, the combustion gas is blown out, the output is lowered, the oil scraping performance is lowered, and the oil consumption is increased.
　このため、リング張力は最適化する必要がある。しかし、燃焼室自体が時々刻々変化するので、最適張力もそれに対応して変化してしまう。最も重要な特性であるガスシール特性を確保するため、どうしても、リング張力は大きくなりがちであり、リングとシリンダ内壁との摩擦力増大という現象をもたらしやすい。この摩擦力の増加により燃費の低下や潤滑不足による焼付きが生じやすくなる。 For this reason, it is necessary to optimize the ring tension. However, since the combustion chamber itself changes from moment to moment, the optimum tension also changes accordingly. In order to ensure the most important characteristic of gas sealing, the ring tension tends to increase inevitably, which tends to cause a phenomenon of increased frictional force between the ring and the inner wall of the cylinder. This increase in frictional force tends to cause seizure due to a reduction in fuel consumption and insufficient lubrication.
　このように、リング張力の増加は、ガスシール特性の向上やオイル消費特性の向上というプラスの効果をもたらす一方、摩擦力増加による燃費特性の悪化、オイル掻き性能の向上による潤滑特性の悪化というマイナスの効果ももたらす。これらのプラスの効果とマイナスの効果はトレードオフの関係にあるので、最適なリング張力を見出し、全ての特性を好ましい方向にもっていくことは、困難であるようにみえる。 In this way, an increase in ring tension has a positive effect of improving gas seal characteristics and oil consumption characteristics, while it has a negative effect of worsening fuel efficiency characteristics due to increased frictional force and worsening lubrication characteristics due to improved oil scraping performance. Also brings the effect. Since these positive and negative effects are in a trade-off relationship, it seems difficult to find the optimum ring tension and bring all the characteristics in the preferred direction.
　このような情況において見えてくる課題は、「ガスシール特性やオイル消費特性を十分に確保した状態で、リングとシリンダ内壁間の摩擦力を低減し、潤滑特性を確保する手段を見いだせるか。」ということであり、別の表現をすれば「ガスシール特性やオイル消費特性を十分に確保するためにリング張力をある程度上げて潤滑油が不足するような摺動環境でも、摺動摩擦力低減や焼付きなどを防止できる潤滑特性を確保する手段を見いだせるか。」ということになる。 The problem that can be seen in this situation is "How can we find a means to reduce the frictional force between the ring and the inner wall of the cylinder and ensure lubrication characteristics while ensuring sufficient gas seal characteristics and oil consumption characteristics?" In other words, "In order to ensure sufficient gas seal characteristics and oil consumption characteristics, even in a sliding environment where the ring tension is increased to some extent and the lubricating oil is insufficient, sliding frictional force reduction and Can you find a means to ensure lubrication properties that can prevent sticking? "
　例えば、リングのガスシール特性を確実に保証し、且つ、焼付きなどが生じないように潤滑を保証し、さらにリングとシリンダ壁間の摩擦力を低くする方法として、外周摺動面にディンプルなどの微細構造を付与する技術が公開されている。 For example, as a method to ensure the gas seal characteristics of the ring and ensure lubrication so that seizure does not occur, and to reduce the frictional force between the ring and the cylinder wall, dimples on the outer peripheral sliding surface, etc. A technology for imparting a fine structure of the above has been disclosed.
　特許文献１は、オイル溜まりとして機能し潤滑性を向上させるための凹部をパルスレーザーで外周摺動面に形成し、当該凹部の径が１００～３００μｍ、深さが１００μｍ以上で、外周摺動面に占める面積割合が５～５０％としたピストンリングを開示している。ここで、深さが１００μｍ以上とするのは、摩耗の進行に対しても凹部が消滅しないようにするためである。 In Patent Document 1, a concave portion that functions as an oil reservoir and improves lubricity is formed on a peripheral sliding surface with a pulse laser, and the concave portion has a diameter of 100 to 300 μm and a depth of 100 μm or more. Discloses a piston ring having an area ratio of 5 to 50%. Here, the depth is set to 100 μm or more so that the concave portion does not disappear even with the progress of wear.
　特許文献２も、低フリクション化に加え、ガスシール、オイルシール機能を低下させることのないというピストンリングを開示している。特許文献２は、凹部が形成されていない凹部非形成領域について着目し、凹部非形成領域のバレル幅領域面積に対する面積率が２０～８５％で、全ての軸方向切断面において凹部非形成領域が存在することが必要であると教示している。また、凹部の寸法については、凹部の開口幅が０．１９ｍｍ×０．１６ｍｍ、深さが１０μｍとした実施例を開示している。 Patent Document 2 also discloses a piston ring that does not lower the gas seal and oil seal functions in addition to reducing friction. Patent Document 2 pays attention to a non-recessed region where no recess is formed, and the area ratio of the non-recessed region to the barrel width region is 20 to 85%, and the non-recessed region is present on all axial cut surfaces. Teaches that it needs to exist. Moreover, about the dimension of a recessed part, the Example which made the opening width of a recessed part 0.19 mm x 0.16 mm and the depth 10 micrometers is disclosed.
　また、特許文献３は、外周摺動面に形成された多数のディンプルは、深さが複数種類となるように形成され、深さの異なる複数種類のディンプルがピストンリングの円周方向に交互に配設されたピストンリングを開示している。具体的には、径が１００μｍ程度、深さが４～５μｍ、２～３μｍ、及び１～１．５μｍの三種類のディンプルを開示している。 In Patent Document 3, a large number of dimples formed on the outer peripheral sliding surface are formed to have a plurality of depths, and a plurality of types of dimples having different depths are alternately arranged in the circumferential direction of the piston ring. Disposed piston rings are disclosed. Specifically, three types of dimples having a diameter of about 100 μm and a depth of 4 to 5 μm, 2 to 3 μm, and 1 to 1.5 μm are disclosed.
　さらに、特許文献４は、硬質皮膜を被覆したピストンリングにおいても複数の凹部を形成する方法として、硬質皮膜被覆前のピストンリング母材にショットピーニングし、その後に硬質皮膜を被覆すれば、オイル溜まりとして作用し、摩耗を防止する微小ディンプルが硬質皮膜被覆後の外周摺動面にも形成できることを開示している。なお、微小ディンプルは、断面が略円弧状の直径０．１～５μｍの凹部であることも開示している。 Further, in Patent Document 4, as a method of forming a plurality of recesses in a piston ring coated with a hard coating, an oil pool is obtained by shot peening the piston ring base material before coating the hard coating and then coating the hard coating. It is disclosed that the fine dimples that act as an anti-wear can be formed on the outer peripheral sliding surface after the hard coating is coated. It is also disclosed that the fine dimple is a concave portion having a diameter of 0.1 to 5 μm with a substantially arc-shaped cross section.
　しかし、上記の先行技術は、いずれも、オイル溜まりとして作用する凹部を外周摺動面に形成することで、潤滑油をいかに多量に保持し又は潤滑油をいかに長期に亘って保持できるか、というものであり、結果的に摩擦力を低減することができるものの、摩擦力の低減には改善の余地があった。 However, all of the above prior arts describe how a large amount of lubricating oil can be retained or how long a lubricating oil can be retained by forming a recess that acts as an oil reservoir on the outer peripheral sliding surface. Although the frictional force can be reduced as a result, there is room for improvement in reducing the frictional force.
特開平５－３４０４７３号公報JP-A-5-340473 特開２０１２－１０７７１０号公報JP 2012-107710 A 特開２０１３－１３７０８０号公報JP2013-137080A 特開２００４－６０８７３号公報JP 2004-60873 A
　本発明は、優れたガスシール特性とオイル消費特性を維持した上で、リングとシリンダ内壁間の摩擦力を低減し、優れた潤滑特性を示すピストンリングを提供することを課題とする。 An object of the present invention is to provide a piston ring that exhibits excellent lubrication characteristics by reducing the frictional force between the ring and the inner wall of the cylinder while maintaining excellent gas seal characteristics and oil consumption characteristics.
　非特許文献１は、バレルフェイス形状のピストンリング２０１が摺動する際に、ピストンリング２０１の外周摺動面２０２とシリンダ内壁２０３との間の潤滑油に発生する圧力分布が、図１５のようになることを開示している。すなわち、外周摺動面２０２のうちピストンリング２０１の進行方向Ｘ側で潤滑油が圧縮され、発生した圧縮力がリング張力を打ち消すことによって摩擦力が低減される。本発明者は、このようなリング張力を打ち消す圧縮力が、摺動面に形成する微細構造に関係して導入できないかどうかについて鋭意研究した結果、微細構造として形成する凹部を潤滑油のスクイーズ効果が発揮されやすい形状とすることによって、摺動面の微細構造に対応したミクロレベルで摩擦力を低減できることに想到した。 In Non-Patent Document 1, the pressure distribution generated in the lubricating oil between the outer peripheral sliding surface 202 of the piston ring 201 and the cylinder inner wall 203 when the barrel face shaped piston ring 201 slides is shown in FIG. Is disclosed. That is, the lubricating oil is compressed in the traveling direction X side of the piston ring 201 in the outer peripheral sliding surface 202, and the generated compressive force cancels the ring tension, thereby reducing the frictional force. As a result of intensive research on whether or not the compressive force that cancels such ring tension can be introduced in relation to the microstructure formed on the sliding surface, the inventor squeezed the recess formed as the microstructure. It was conceived that the frictional force can be reduced at a micro level corresponding to the fine structure of the sliding surface by adopting a shape that makes it easy to exhibit.
　すなわち、本発明のピストンリングは、外周摺動面に凹部が形成されたピストンリングであって、前記凹部が、外径が最も小さい最深部と、前記最深部に向かって漸次縮径する傾斜部と、を有することを特徴とする。 That is, the piston ring of the present invention is a piston ring in which a concave portion is formed on an outer peripheral sliding surface, and the concave portion has a deepest portion having the smallest outer diameter and an inclined portion that gradually decreases in diameter toward the deepest portion. It is characterized by having.
　また、本発明のピストンリングにおいて、前記傾斜部は、前記最深部と連続することが好ましい。 In the piston ring of the present invention, it is preferable that the inclined portion is continuous with the deepest portion.
　また、本発明のピストンリングにおいて、前記傾斜部は、凸状となる湾曲部を含むことが好ましい。 In the piston ring of the present invention, it is preferable that the inclined portion includes a curved portion that is convex.
　また、本発明のピストンリングにおいて、前記凹部は、外径が周囲よりも大きい頂部を更に有し、前記傾斜部は、前記頂部に向かって漸次拡径することが好ましい。 In the piston ring of the present invention, it is preferable that the concave portion further has a top portion having an outer diameter larger than that of the surroundings, and the inclined portion gradually increases in diameter toward the top portion.
　また、本発明のピストンリングにおいて、前記凹部は複数形成され、前記複数の凹部は、前記最深部の外径がそれぞれ異なる２以上の凹部を含むことが好ましい。 In the piston ring of the present invention, it is preferable that a plurality of the recesses are formed, and the plurality of recesses include two or more recesses having different outer diameters of the deepest part.
　また、本発明のピストンリングにおいて、前記凹部は、所定の方向に沿って延在する溝部であることが好ましい。 In the piston ring of the present invention, it is preferable that the concave portion is a groove portion extending along a predetermined direction.
　また、本発明のピストンリングにおいて、前記溝部は、円周方向に沿って延在することが好ましい。 In the piston ring of the present invention, it is preferable that the groove portion extends along the circumferential direction.
　また、本発明のピストンリングにおいて、前記溝部は複数形成され、前記複数の溝部は、円周方向に沿って配置されていることが好ましい。 In the piston ring of the present invention, it is preferable that a plurality of the groove portions are formed, and the plurality of groove portions are arranged along the circumferential direction.
　また、本発明のピストンリングにおいて、前記溝部は、周囲よりも軸方向に延在する軸方向延在部を更に有することが好ましい。 Further, in the piston ring of the present invention, it is preferable that the groove portion further has an axially extending portion that extends in the axial direction from the periphery.
　また、本発明のピストンリングにおいて、前記凹部は、合口部には到達していないことが好ましい。 In the piston ring of the present invention, it is preferable that the concave portion does not reach the abutment portion.
　また、本発明のピストンリングにおいて、前記外周摺動面を被覆する硬質皮膜を備えることが好ましい。 Further, in the piston ring of the present invention, it is preferable that a hard coating for covering the outer peripheral sliding surface is provided.
　本発明によれば、優れたガスシール特性とオイル消費特性を維持した上で、ピストンリングとシリンダ内壁との間の摩擦力を低減し、優れた潤滑特性を示すピストンリングを提供することができる。 According to the present invention, it is possible to provide a piston ring that exhibits excellent lubrication characteristics by reducing the frictional force between the piston ring and the cylinder inner wall while maintaining excellent gas seal characteristics and oil consumption characteristics. .
本発明の一実施形態としてのピストンリングの平面図である。It is a top view of the piston ring as one embodiment of the present invention. 図１に示すピストンリングの外周摺動面の構成を示す側面図である。It is a side view which shows the structure of the outer peripheral sliding surface of the piston ring shown in FIG. 図２のＩＩＩ―ＩＩＩ線に沿う断面図であり、図３（ａ）は外周摺動面が摩耗する前、図３（ｂ）は外周摺動面が摩耗した後の様子をそれぞれ示す。3A and 3B are cross-sectional views taken along the line III-III in FIG. 2. FIG. 3A shows a state before the outer peripheral sliding surface is worn, and FIG. 3B shows a state after the outer peripheral sliding surface is worn. 図１に示すピストンリングの外周摺動面に形成される溝部の他の例を示す断面図である。It is sectional drawing which shows the other example of the groove part formed in the outer periphery sliding surface of the piston ring shown in FIG. 図１に示すピストンリングの外周摺動面に形成される溝部の更に他の例を示す断面図である。It is sectional drawing which shows the further another example of the groove part formed in the outer peripheral sliding surface of the piston ring shown in FIG. 図１に示すピストンリングの外周摺動面に形成される溝部の最深部の関係の一例を示す断面図である。It is sectional drawing which shows an example of the relationship of the deepest part of the groove part formed in the outer peripheral sliding surface of the piston ring shown in FIG. 図１に示すピストンリングの外周摺動面に形成される溝部の他の例を示す側面図である。It is a side view which shows the other example of the groove part formed in the outer periphery sliding surface of the piston ring shown in FIG. 図１に示すピストンリングの外周摺動面に形成される溝部の更に他の例を示す側面図である。It is a side view which shows the further another example of the groove part formed in the outer periphery sliding surface of the piston ring shown in FIG. 図１に示すピストンリングの外周摺動面の構成の更に他の例を示す側面図である。It is a side view which shows the further another example of a structure of the outer periphery sliding surface of the piston ring shown in FIG. 図１に示すピストンリングの合口部の周囲の構成を示す側面図である。It is a side view which shows the structure of the circumference | surroundings of the joint part of the piston ring shown in FIG. 図１に示すピストンリングの外周摺動面に形成される溝部の更に他の例を示す側面図である。It is a side view which shows the further another example of the groove part formed in the outer periphery sliding surface of the piston ring shown in FIG. ピストンリングの外周摺動面に溝部を形成する様子を示す図である。It is a figure which shows a mode that a groove part is formed in the outer peripheral sliding surface of a piston ring. 図１２のピストンリングの外周摺動面に形成された溝部の一例を示す側面図である。It is a side view which shows an example of the groove part formed in the outer periphery sliding surface of the piston ring of FIG. 図１２のピストンリングの外周摺動面に形成された溝部の一例を示す軸方向に沿う断面図である。It is sectional drawing which follows an axial direction which shows an example of the groove part formed in the outer peripheral sliding surface of the piston ring of FIG. バレルフェイス形状のピストンリング摺動時におけるリピストンリングとシリンダ内壁との間の潤滑油に発生する圧縮力の圧力分布を示す図である。It is a figure which shows the pressure distribution of the compressive force which generate | occur | produces in the lubricating oil between a repiston ring and a cylinder inner wall at the time of barrel face shape piston ring sliding.
　以下、本発明の各実施形態について、図面を参照して説明する。各図において共通の構成には、同一の符号を付している。 Hereinafter, each embodiment of the present invention will be described with reference to the drawings. In each figure, the same code | symbol is attached | subjected to the common structure.
（第１実施形態）
　図１は、本発明の一実施形態としてのピストンリング１の平面図である。ピストンリング１は、バレルフェイス形状に形成され、例えば自動車等のエンジン（内燃機関）のピストンにトップリング（第１圧力リング）として装着して使用されるものである。また、ピストンリング１は、合口部２０を備えた割りリング形状に形成されている。ピストンリング１の外面は、シリンダ内壁と摺動する外周摺動面１０を構成する。ここで、ピストンリング１の中心軸をＯとし、ピストンリング１の外周摺動面１０に沿う円周方向をＡ、中心軸Ｏに沿う軸方向をＢとする。ピストンリング１は、軸方向Ｂに沿ってシリンダ内壁と摺動する。 (First embodiment)
FIG. 1 is a plan view of a piston ring 1 as an embodiment of the present invention. The piston ring 1 is formed in a barrel face shape, and is used by being mounted as a top ring (first pressure ring) on a piston of an engine (internal combustion engine) such as an automobile. Further, the piston ring 1 is formed in a split ring shape provided with the joint portion 20. The outer surface of the piston ring 1 constitutes an outer peripheral sliding surface 10 that slides with the cylinder inner wall. Here, the central axis of the piston ring 1 is O, the circumferential direction along the outer peripheral sliding surface 10 of the piston ring 1 is A, and the axial direction along the central axis O is B. The piston ring 1 slides along the axial direction B with the cylinder inner wall.
＜外周摺動面１０の微細構造＞
　以下、外周摺動面１０の微細構造について説明する。図２は、ピストンリング１の外周摺動面１０の構成を示す側面図である。図２に示すように、ピストンリング１の外周摺動面１０には、微細構造としての凹部である溝部１００が複数形成されている。溝部１００は、それぞれ円周方向Ａに沿って延在し、複数の溝部１００は、円周方向Ａ及び軸方向Ｂ（ピストンリング１の中心軸Ｏに沿う方向）のそれぞれに沿って配置されている。ここで、ピストンリング１の外周摺動面１０に形成される複数の溝部１００の合計面積率は、外周摺動面１０の面積に対し２０％以上８０％以下であることが好ましい。 <Microstructure of outer peripheral sliding surface 10>
Hereinafter, the fine structure of the outer peripheral sliding surface 10 will be described. FIG. 2 is a side view showing the configuration of the outer peripheral sliding surface 10 of the piston ring 1. As shown in FIG. 2, the outer peripheral sliding surface 10 of the piston ring 1 is formed with a plurality of groove portions 100 that are concave portions as fine structures. The groove portions 100 respectively extend along the circumferential direction A, and the plurality of groove portions 100 are arranged along the circumferential direction A and the axial direction B (direction along the central axis O of the piston ring 1). Yes. Here, the total area ratio of the plurality of groove portions 100 formed on the outer peripheral sliding surface 10 of the piston ring 1 is preferably 20% or more and 80% or less with respect to the area of the outer peripheral sliding surface 10.
　図３は、図２のＩＩＩ―ＩＩＩ線に沿う断面図であり、図３（ａ）は外周摺動面１０が摩耗する前、図３（ｂ）は外周摺動面１０が摩耗した後の様子をそれぞれ示す。図３（ａ）に示すように、溝部１００は、外径又は中心軸Ｏからの半径が最も小さい最深部１１０と、最深部１１０に向かって外径又は中心軸からの半径が漸次縮径する傾斜部１２０と、を有する。最深部１１０は、軸方向Ｂに沿って延在している。傾斜部１２０は、最深部１１０の軸方向Ｂに沿う両側に、最深部１１０と連続して配置されている。換言すると、傾斜部１２０は、最深部１１０と隣り合って配置されている。 3 is a cross-sectional view taken along the line III-III in FIG. 2. FIG. 3 (a) is before the outer peripheral sliding surface 10 is worn, and FIG. 3 (b) is after the outer peripheral sliding surface 10 is worn. Each state is shown. As shown in FIG. 3A, the groove portion 100 has a deepest portion 110 having the smallest outer diameter or radius from the central axis O, and a radius from the outer diameter or the central axis gradually decreases toward the deepest portion 110. And an inclined portion 120. The deepest portion 110 extends along the axial direction B. The inclined portion 120 is continuously arranged with the deepest portion 110 on both sides along the axial direction B of the deepest portion 110. In other words, the inclined portion 120 is disposed adjacent to the deepest portion 110.
　溝部１００には、潤滑油が保持される。なお、溝部１００は、最深部１１０が軸方向Ｂに沿って所定長さ延在するため、最深部１１０が軸方向Ｂの一点のみで形成され軸方向Ｂに沿って所定長さ延在しない場合に比べて、潤滑油をより多く保持することができる。ピストンリング１が摺動方向（軸方向Ｂ）に沿って摺動すると、溝部１００の最深部１１０に保持された潤滑油が軸方向Ｂに沿って傾斜部１２０に押し出される。ここで、溝部１００において、傾斜部１２０の外周摺動面１０からの深さは最深部１１０の外周摺動面１０からの深さよりも浅いため、最深部１１０から傾斜部１２０に押し出された潤滑油は深さ方向に絞られることで圧縮され、圧力上昇によってスクイーズ効果が発現する。すなわち、最深部１１０から傾斜部１２０に潤滑油が押し出されることにより油膜圧力が上昇し、シリンダ内壁に作用しているピストンリング１の張力が打ち消されるので、ピストンリング１とシリンダ内壁との間の摩擦力を低減し、優れた潤滑特性を示すことになる。なお、ピストンリング１は、外周摺動面１０に複数の溝部１００を有するため、それぞれの溝部１００によって上述の効果を得ることができる。 Lubricating oil is held in the groove portion 100. In addition, since the deepest part 110 extends a predetermined length along the axial direction B, the deepest part 110 is formed only at one point in the axial direction B and does not extend the predetermined length along the axial direction B. Compared to the above, more lubricating oil can be retained. When the piston ring 1 slides along the sliding direction (axial direction B), the lubricating oil held in the deepest portion 110 of the groove 100 is pushed out to the inclined portion 120 along the axial direction B. Here, in the groove portion 100, since the depth of the inclined portion 120 from the outer peripheral sliding surface 10 is shallower than the depth of the deepest portion 110 from the outer peripheral sliding surface 10, lubrication pushed out from the deepest portion 110 to the inclined portion 120. Oil is compressed by being squeezed in the depth direction, and a squeeze effect is manifested by an increase in pressure. That is, when the lubricating oil is pushed out from the deepest portion 110 to the inclined portion 120, the oil film pressure rises, and the tension of the piston ring 1 acting on the cylinder inner wall is canceled out. The frictional force is reduced and excellent lubrication characteristics are exhibited. In addition, since the piston ring 1 has the some groove part 100 in the outer periphery sliding surface 10, the above-mentioned effect can be acquired by each groove part 100. FIG.
　さらに、ピストンリング１の溝部１００の円周方向Ａに沿う断面形状は、図３（ａ）に示すような溝部１００の断面形状を形成させてもよい。これにより、ピストンリング１がピストン速度がゼロとなる上死点及び下死点の位置に到達したとき、溝部１００内に保持された潤滑油が、傾斜部１２０により円周方向Ａに沿って絞り出され易くなるため、より一層シリンダ内壁との間の摩擦力を低減することができる。 Furthermore, the cross-sectional shape along the circumferential direction A of the groove portion 100 of the piston ring 1 may form a cross-sectional shape of the groove portion 100 as shown in FIG. Thereby, when the piston ring 1 reaches the positions of the top dead center and the bottom dead center at which the piston speed becomes zero, the lubricating oil held in the groove portion 100 is squeezed along the circumferential direction A by the inclined portion 120. Since it becomes easy to take out, the frictional force between cylinder inner walls can be reduced further.
　加えて、図３（ａ）に示す溝部１００の断面形状を円周方向Ａかつ軸方向Ｂに沿って形成させてもよい。これにより、図３（ａ）に示す溝部１００の断面形状を軸方向Ｂに沿って形成したことにより得られる上述の効果と、円周方向Ａに沿って形成したことにより得られる上述の効果とを共に得ることができる。 In addition, the cross-sectional shape of the groove 100 shown in FIG. 3A may be formed along the circumferential direction A and the axial direction B. Thereby, the above-mentioned effect obtained by forming the cross-sectional shape of the groove part 100 shown in FIG. 3A along the axial direction B and the above-described effect obtained by forming along the circumferential direction A Can be obtained together.
　溝部１００の傾斜部１２０は、凸状となる湾曲部１２１を含む。詳細には、湾曲部１２１は、最深部１１０と連続する位置では傾斜が急であり、最深部１１０から離れるにつれて徐々に傾斜がなだらかとなっている。このように、傾斜部１２０が湾曲部１２１を含むことで、最深部１１０から押し出される潤滑油が急激に圧縮されることになるため、上述のスクイーズ効果を顕著に発揮することができる。詳細には、図３（ａ）に示す溝部１００の断面形状を軸方向Ｂに沿って形成した場合には、湾曲部１２１によって動圧効果が得られる。また、図３（ａ）に示す溝部１００の断面形状を円周方向Ａに沿って形成した場合には、ピストンリング１のピストン速度がゼロとなるときに、溝部１００内に保持された潤滑油が、スクイーズ効果により潤滑油が溝部１００から円周方向Ａに沿って絞り出される潤滑油が、湾曲部１２１によって円周方向Ａに沿ってより絞り出されやすくなるため、更によりシリンダ内壁との摩擦力を低減することができる。溝部１００の最深部１１０における外周摺動面１０からの深さＤは、１μｍ以下であることが好ましく、０．２μｍ以下であることがより好ましい。 The inclined part 120 of the groove part 100 includes a curved part 121 having a convex shape. Specifically, the bending portion 121 has a steep slope at a position continuous with the deepest portion 110, and gradually slopes gradually away from the deepest portion 110. Thus, since the inclined portion 120 includes the curved portion 121, the lubricating oil pushed out from the deepest portion 110 is rapidly compressed, so that the above-described squeeze effect can be exhibited remarkably. Specifically, when the cross-sectional shape of the groove 100 shown in FIG. 3A is formed along the axial direction B, a dynamic pressure effect is obtained by the curved portion 121. Further, when the cross-sectional shape of the groove 100 shown in FIG. 3A is formed along the circumferential direction A, the lubricating oil retained in the groove 100 when the piston speed of the piston ring 1 becomes zero. However, the lubricating oil from which the lubricating oil is squeezed out along the circumferential direction A from the groove portion 100 due to the squeeze effect is more easily squeezed out along the circumferential direction A by the curved portion 121. The frictional force can be reduced. The depth D from the outer peripheral sliding surface 10 in the deepest part 110 of the groove part 100 is preferably 1 μm or less, and more preferably 0.2 μm or less.
　溝部１００の軸方向Ｂに沿う幅Ｗは、０．３ｍｍ以下であることが好ましく、０．１ｍｍ以下であることがより好ましい。 The width W along the axial direction B of the groove part 100 is preferably 0.3 mm or less, and more preferably 0.1 mm or less.
　図３（ｂ）において、摩耗前の外周摺動面１０を破線で示す。図３（ｂ）に示すように、溝部１００は、ピストンリング１がシリンダ内壁と摺動を繰り返すことで外周摺動面１０が摩耗した場合であっても、摩耗前と同様に最深部１１０と傾斜部１２０とを有するため、上述した摩耗前と同様の効果を得ることができる。なお、以下では、外周摺動面１０が摩耗する前のピストンリング１の構成について説明する。 In FIG. 3B, the outer peripheral sliding surface 10 before wear is indicated by a broken line. As shown in FIG. 3 (b), the groove 100 has the deepest portion 110 in the same manner as before the wear even when the outer peripheral sliding surface 10 is worn by the piston ring 1 repeatedly sliding with the cylinder inner wall. Since it has the inclined part 120, the same effect as before the abrasion described above can be obtained. In the following, the configuration of the piston ring 1 before the outer peripheral sliding surface 10 is worn will be described.
　図４は、ピストンリング１の外周摺動面１０に形成される溝部１００の他の例を示す断面図である。図４（ａ）～図４（ｆ）に示す各断面は、外周摺動面１０に直交する所定の断面視である。なお、外周摺動面１０に直交する所定の断面視としては、例えば、円周方向Ａに沿う断面視や、軸方向Ｂに沿う断面視が挙げられるが、図４（ａ）～図４（ｆ）では、円周方向Ａに沿う断面視（軸方向Ｂと直交する断面視と同じ）を例示している。 FIG. 4 is a cross-sectional view showing another example of the groove portion 100 formed on the outer peripheral sliding surface 10 of the piston ring 1. Each of the cross sections shown in FIGS. 4A to 4F is a predetermined cross-sectional view orthogonal to the outer peripheral sliding surface 10. Note that examples of the predetermined cross-sectional view orthogonal to the outer peripheral sliding surface 10 include a cross-sectional view along the circumferential direction A and a cross-sectional view along the axial direction B. FIG. 4 (a) to FIG. f) illustrates a cross-sectional view along the circumferential direction A (same as a cross-sectional view orthogonal to the axial direction B).
　図４（ａ）に示す溝部１００の断面形状は、最深部１１０が円周方向Ａの一点で形成され円周方向Ａに沿って延在していないこと以外は、図３（ａ）に示した断面形状と同様である。上述したように、円周方向Ａに沿って延在する最深部１１０に潤滑油を多く保持することができる点で、図３（ａ）に示した断面形状を有する溝部１００の方が図４（ａ）に示す断面形状を有する溝部１００よりも好ましい。 The cross-sectional shape of the groove portion 100 shown in FIG. 4A is shown in FIG. 3A except that the deepest portion 110 is formed at one point in the circumferential direction A and does not extend along the circumferential direction A. This is the same as the cross-sectional shape. As described above, the groove portion 100 having the cross-sectional shape shown in FIG. 3A is more suitable for the groove portion 100 shown in FIG. 3A in that a lot of lubricating oil can be held in the deepest portion 110 extending along the circumferential direction A. It is more preferable than the groove part 100 which has the cross-sectional shape shown to (a).
　図４（ｂ）に示す溝部１００の断面形状は、傾斜部１２０が最深部１１０の円周方向Ａに沿う一方側のみに配置されていること以外は、図４（ａ）に示した断面形状と同様である。なお、図４（ａ）及び図４（ｂ）では、外周摺動面１０に直交する所定の断面視として円周方向Ａに沿う断面視を示しているが、図４（ａ）及び図４（ｂ）を軸方向Ｂに沿う断面視とした場合には、図４（ａ）に示した断面形状を有する溝部１００では、ピストンリング１が軸方向Ｂに沿う一方向に摺動する際には、潤滑油が一方の傾斜部１２０に押し出され、軸方向Ｂに沿う反対方向に摺動する際には、潤滑油が他方の傾斜部１２０に押し出されることになる。よって、図４（ａ）に示した断面形状を有する溝部１００は、図４（ｂ）に示す断面形状を有する溝部１００より高いスクイーズ効果を得ることができる。 The cross-sectional shape of the groove portion 100 shown in FIG. 4B is the cross-sectional shape shown in FIG. 4A except that the inclined portion 120 is disposed only on one side along the circumferential direction A of the deepest portion 110. It is the same. 4 (a) and 4 (b) show a cross-sectional view along the circumferential direction A as a predetermined cross-sectional view orthogonal to the outer peripheral sliding surface 10, but FIG. 4 (a) and FIG. When (b) is a sectional view along the axial direction B, when the piston ring 1 slides in one direction along the axial direction B in the groove portion 100 having the sectional shape shown in FIG. When the lubricating oil is pushed out to one inclined portion 120 and slides in the opposite direction along the axial direction B, the lubricating oil is pushed out to the other inclined portion 120. Therefore, the groove part 100 having the cross-sectional shape shown in FIG. 4A can obtain a higher squeeze effect than the groove part 100 having the cross-sectional shape shown in FIG.
　図４（ｃ）は、図４（ｂ）に示した断面形状を有する溝部１００が、互いに最深部１１０が隣り合うように配置された例を示す。図４（ｂ）の断面形状を有する溝部１００は、図４（ｃ）のように配置することにより、図４（ｃ）を軸方向Ｂに沿う断面視とした場合には、軸方向Ｂに沿ってどちらに摺動する場合でも、摺動方向によらずに略一定のスクイーズ効果を得ることができる。 FIG. 4C shows an example in which the groove portions 100 having the cross-sectional shape shown in FIG. 4B are arranged so that the deepest portions 110 are adjacent to each other. The groove portion 100 having the cross-sectional shape of FIG. 4B is arranged as shown in FIG. 4C, so that when the cross-sectional view of FIG. Regardless of the sliding direction, a substantially constant squeeze effect can be obtained regardless of the sliding direction.
　図４（ｄ）に示す断面形状を有する溝部１００は、最深部１１０と、最深部１１０に連続して配置され、最深部１１０に向かって漸次縮径する傾斜部１２０と、に加えて、外径又は半径が周囲よりも大きい頂部１３０を有し、傾斜部１２０は頂部１３０に向かって漸次拡径している。頂部１３０は、外周摺動面１０よりも外径又は半径が小さいため、シリンダ内壁とは接触しない。図４（ｄ）に示す傾斜部１２０は、凸状の湾曲部１２１により構成されている。 The groove portion 100 having the cross-sectional shape shown in FIG. 4D includes the deepest portion 110 and the inclined portion 120 that is arranged continuously to the deepest portion 110 and gradually decreases in diameter toward the deepest portion 110. The top portion 130 has a larger diameter or radius than the surroundings, and the inclined portion 120 gradually increases in diameter toward the top portion 130. Since the top 130 has an outer diameter or radius smaller than that of the outer peripheral sliding surface 10, it does not contact the cylinder inner wall. The inclined portion 120 shown in FIG. 4D is configured by a convex curved portion 121.
　図４（ｄ）に示す断面形状を有する溝部１００では、ピストンリング１が摺動方向（軸方向Ｂ）に沿って摺動する際、最深部１１０から押し出された潤滑油が傾斜部１２０上を通って頂部１３０に到達し、潤滑油は溝部１００内に保持され続ける。すなわち、ピストンリング１が摺動しても溝部１００とシリンダ内壁との間に油膜が形成され続けるため、せん断応力が抑制され、摩擦抵抗が上がることを抑制できる。 In the groove portion 100 having the cross-sectional shape shown in FIG. 4D, when the piston ring 1 slides along the sliding direction (axial direction B), the lubricating oil pushed out from the deepest portion 110 moves on the inclined portion 120. Passing through to the top 130, the lubricant continues to be retained in the groove 100. That is, even if the piston ring 1 slides, an oil film is continuously formed between the groove portion 100 and the cylinder inner wall, so that shear stress can be suppressed and increase in frictional resistance can be suppressed.
　図４（ｅ）は、図４（ｂ）に示した断面形状を有する溝部１００が、互いに傾斜部１２０が隣り合うように配置された例を示す。溝部１００を図４（ｅ）に示すように配置することで、図４（ｃ）と同様、図４（ｅ）を軸方向Ｂに沿う断面視とした場合には、軸方向Ｂに沿ってどちらに摺動する場合でも、摺動方向によらずに略一定のスクイーズ効果を得ることができる。 FIG. 4E shows an example in which the groove portions 100 having the cross-sectional shape shown in FIG. 4B are arranged so that the inclined portions 120 are adjacent to each other. By arranging the groove portion 100 as shown in FIG. 4 (e), as in FIG. 4 (c), when FIG. 4 (e) is a cross-sectional view along the axial direction B, it follows along the axial direction B. In either case, a substantially constant squeeze effect can be obtained regardless of the sliding direction.
　図４（ｆ）は、図４（ｄ）に示した断面形状を有する溝部１００において、傾斜部１２０に代えて複数の傾斜部１２０を有し、それぞれの傾斜部１２０の外径が頂部１３０に向かって漸次拡径するように配置された例を示す。ここで、それぞれの傾斜部１２０の境界には、段差面１２２を介して頂部１３０側に縮径した縮径部１２３が形成されている。また、それぞれの傾斜部１２０は、凸状の湾曲部１２１により構成されている。このように、摺動方向に対して、段差面１２２を介して傾斜部１２０を複数繋げることによって、より一層の絞り効果を得ることができる。 FIG. 4F shows a groove portion 100 having the cross-sectional shape shown in FIG. The example arrange | positioned so that it may expand gradually gradually toward the direction is shown. Here, a diameter-reduced portion 123 that is reduced in diameter toward the top portion 130 via the step surface 122 is formed at the boundary of each inclined portion 120. In addition, each inclined portion 120 is configured by a convex curved portion 121. In this way, by connecting a plurality of inclined portions 120 via the step surface 122 with respect to the sliding direction, a further narrowing effect can be obtained.
　図５は、ピストンリング１の外周摺動面１０に形成される溝部１００の更に他の例を示す断面図である。図５に示すように、溝部１００は、傾斜部１２０が湾曲部１２１を含まず、略直線状に形成されていてもよい。また、図５に示すように、溝部１００は、非連続的に配置された複数の傾斜部１２０を有していてもよい。ここで、略直線状の傾斜部１２０の傾斜角度は、０．２°以上２°以下であることが好ましく、０．２°以上０．５°以下であることがより好ましい。なお、図５は、外周摺動面１０に直交する所定の断面視として、円周方向Ａに沿う断面視（軸方向Ｂと直交する断面視と同じ）を示しているが、軸方向Ｂに沿う断面視としてもよい。 FIG. 5 is a cross-sectional view showing still another example of the groove portion 100 formed on the outer peripheral sliding surface 10 of the piston ring 1. As shown in FIG. 5, in the groove part 100, the inclined part 120 does not include the curved part 121 and may be formed in a substantially linear shape. Moreover, as shown in FIG. 5, the groove part 100 may have the some inclination part 120 arrange | positioned discontinuously. Here, the inclination angle of the substantially linear inclined portion 120 is preferably not less than 0.2 ° and not more than 2 °, and more preferably not less than 0.2 ° and not more than 0.5 °. FIG. 5 shows a cross-sectional view along the circumferential direction A (same as a cross-sectional view orthogonal to the axial direction B) as a predetermined cross-sectional view orthogonal to the outer peripheral sliding surface 10. It is good also as a sectional view along.
　図６は、ピストンリング１の外周摺動面１０に形成される溝部１００の最深部１１０の関係の一例を示す断面図である。ここで、図６に示す溝部１００の断面形状は、最深部１１０の外周摺動面１０からの深さＤ１～Ｄ３を説明するために簡略化して示している。図６に示すように、溝部１００は、外周摺動面１０に直交する所定の断面視において複数形成されていてもよい。ここで、所定の断面視において複数形成された溝部１００は、円周方向Ａのいずれかの位置及び軸方向Ｂのいずれかの位置でも連通していない。つまり、図６に示す３つの溝部１００は互いに連通していない別々の構成である。図６に示すように、３つの溝部１００の最深部１１０の深さＤ１～Ｄ３は、それぞれ異なっている。すなわち、複数形成された溝部１００は、最深部１１０の外径又は半径がそれぞれ異なる２以上の溝部１００を含んでいてもよい。 FIG. 6 is a cross-sectional view showing an example of the relationship of the deepest part 110 of the groove part 100 formed on the outer peripheral sliding surface 10 of the piston ring 1. Here, the cross-sectional shape of the groove portion 100 shown in FIG. 6 is simplified for explaining the depths D1 to D3 from the outer peripheral sliding surface 10 of the deepest portion 110. As shown in FIG. 6, a plurality of groove portions 100 may be formed in a predetermined cross-sectional view orthogonal to the outer peripheral sliding surface 10. Here, the plurality of groove portions 100 formed in a predetermined cross-sectional view do not communicate at any position in the circumferential direction A and any position in the axial direction B. That is, the three groove parts 100 shown in FIG. 6 are separate structures that are not in communication with each other. As shown in FIG. 6, the depths D1 to D3 of the deepest portions 110 of the three groove portions 100 are different from each other. That is, the plurality of formed groove portions 100 may include two or more groove portions 100 having different outer diameters or radii of the deepest portion 110.
　図６に示すように、所定の断面視において、最深部１１０の外径がそれぞれ異なる２以上の溝部１００を含ませることで、ピストンリング１の位置に応じて所望の潤滑特性を発現させることができる。 As shown in FIG. 6, by including two or more groove portions 100 having different outer diameters of the deepest portion 110 in a predetermined cross-sectional view, desired lubrication characteristics can be exhibited depending on the position of the piston ring 1. it can.
　図７は、ピストンリング１の外周摺動面１０に形成される溝部１００の他の例を示す側面図である。図７（ａ）に示すように、ピストンリング１の外周摺動面１０に形成される複数の溝部１００は、軸方向Ｂに沿って互い違いとなる千鳥状に配置してもよい。このように配置しても、充分な摩擦力低減効果を得ることができる。 FIG. 7 is a side view showing another example of the groove portion 100 formed on the outer peripheral sliding surface 10 of the piston ring 1. As shown in FIG. 7A, the plurality of grooves 100 formed on the outer peripheral sliding surface 10 of the piston ring 1 may be arranged in a staggered manner along the axial direction B. Even if it arrange | positions in this way, sufficient frictional force reduction effect can be acquired.
　また、図７（ｂ）に示すように、溝部１００は、円周方向Ａに沿って両端側に向かうにつれて、軸方向Ｂに沿う幅が縮小するように形成してもよい。このような溝部１００の側面視における形状を、例えば図３（ａ）や図４（ａ）に示したような最深部１１０の円周方向Ａの両端側の外径が徐々に拡径する形状と組み合わせることで、スクイーズ効果を更に高めることができる。図７（ｂ）に示す溝部１００の軸方向Ｂに沿う幅は、円周方向Ａに沿う中心部では０．２ｍｍ超であり、円周方向Ａに沿う両端では０．２ｍｍ以下であることが好ましい。 Further, as shown in FIG. 7B, the groove portion 100 may be formed such that the width along the axial direction B decreases as it goes toward both ends along the circumferential direction A. The shape of the groove portion 100 in a side view is, for example, a shape in which the outer diameters at both ends in the circumferential direction A of the deepest portion 110 gradually increase as shown in FIG. 3A and FIG. By combining with squeeze effect can be further enhanced. The width along the axial direction B of the groove portion 100 shown in FIG. 7B is more than 0.2 mm at the central portion along the circumferential direction A, and is 0.2 mm or less at both ends along the circumferential direction A. preferable.
　図８及び図９は、ピストンリング１の外周摺動面１０に形成される溝部１００の更に他の例を示す側面図である。図８（ａ）に示すように、溝部１００は、円周方向Ａに沿って直線状に連続的に延在していてもよい。また、図８（ｂ）に示すように、溝部１００は、円周方向Ａに沿って連続的に延在しつつ、周囲よりも軸方向Ｂに延在する軸方向延在部１４０を含むようにジグザグ状に形成されていてもよい。このように、溝部１００が軸方向延在部１４０を有することで、ピストンリング１がシリンダ内壁に対して軸方向Ｂに沿って摺動すると、溝部１００に保持された潤滑油が慣性力によって軸方向延在部１４０に集中する。これにより、軸方向延在部１４０で潤滑油が圧縮され、圧力上昇によってスクイーズ効果が発現し易い。 8 and 9 are side views showing still another example of the groove portion 100 formed on the outer peripheral sliding surface 10 of the piston ring 1. As shown in FIG. 8A, the groove 100 may continuously extend linearly along the circumferential direction A. Further, as shown in FIG. 8B, the groove portion 100 includes an axially extending portion 140 that extends continuously in the circumferential direction A but extends in the axial direction B from the periphery. Alternatively, it may be formed in a zigzag shape. Thus, since the groove part 100 has the axially extending part 140, when the piston ring 1 slides along the axial direction B with respect to the inner wall of the cylinder, the lubricating oil held in the groove part 100 is axially driven by inertial force. Concentrate on the direction extension 140. As a result, the lubricating oil is compressed by the axially extending portion 140, and a squeeze effect is likely to be manifested by an increase in pressure.
　図８（ｃ）に示すように、図８（ｂ）に示した溝部１００が分断されたように、円周方向Ａに沿ってジグザグ状に配置された複数の溝部１００を形成してもよい。図８（ｃ）に示す溝部１００は、それぞれ軸方向延在部１４０を有する。図８（ｃ）に示す溝部１００の方が、図８（ｂ）に示した溝部１００よりも、潤滑油の円周方向Ａにおける流れの分散が抑制できる点で好ましい。さらに、図８（ｄ）に示すように、Ｖ字状の溝部１００が、円周方向Ａに沿って配置されていてもよい。図８（ｄ）に示す溝部１００は、軸方向Ｂに沿う両端に軸方向延在部１４０を有する。 As shown in FIG. 8C, a plurality of grooves 100 arranged in a zigzag shape along the circumferential direction A may be formed so that the grooves 100 shown in FIG. 8B are divided. . Each groove 100 shown in FIG. 8C has an axially extending portion 140. The groove portion 100 shown in FIG. 8C is preferable to the groove portion 100 shown in FIG. 8B in that the dispersion of the flow of the lubricating oil in the circumferential direction A can be suppressed. Further, as illustrated in FIG. 8D, the V-shaped groove portion 100 may be disposed along the circumferential direction A. The groove portion 100 shown in FIG. 8D has axially extending portions 140 at both ends along the axial direction B.
　図９（ａ）に示すように、溝部１００は、円周方向Ａに沿って直線状に連続的に延在しつつ、一定間隔で軸方向延在部１４０を有していてもよい。また、図９（ｂ）に示すように、図９（ａ）に示した溝部１００が分断されたように、円周方向Ａに沿って配置された複数の溝部１００を形成してもよい。図９（ｂ）に示す溝部１００は、それぞれ軸方向延在部１４０を有する。図９（ｂ）に示す溝部１００の方が、図９（ａ）に示した溝部１００よりも、潤滑油の円周方向Ａにおける流れの分散が抑制できる点で好ましい。 As shown in FIG. 9A, the groove portion 100 may have the axially extending portions 140 at regular intervals while continuously extending linearly along the circumferential direction A. Further, as shown in FIG. 9B, a plurality of groove portions 100 arranged along the circumferential direction A may be formed so that the groove portion 100 shown in FIG. 9A is divided. Each groove portion 100 shown in FIG. 9B has an axially extending portion 140. The groove part 100 shown in FIG. 9B is preferable to the groove part 100 shown in FIG. 9A in that the dispersion of the flow of the lubricating oil in the circumferential direction A can be suppressed.
　図９（ｃ）は、図９（ａ）及び図９（ｂ）の溝部１００の軸方向延在部１４０の拡大図である。図９（ｃ）に示すように、軸方向延在部１４０は、先端に向かうにつれて円周方向Ａに沿う長さが漸次縮小することが好ましく、凹状に湾曲することが更に好ましい。軸方向延在部１４０がこのように形成されることで、スクイーズ効果をより発現させることができる。 FIG. 9 (c) is an enlarged view of the axially extending portion 140 of the groove portion 100 of FIGS. 9 (a) and 9 (b). As shown in FIG. 9C, it is preferable that the axially extending portion 140 is gradually reduced in length along the circumferential direction A toward the tip, and more preferably curved in a concave shape. By forming the axially extending portion 140 in this manner, a squeeze effect can be further exhibited.
　図１０は、ピストンリング１の合口部２０の周囲の構成を示す側面図である。図１０に示すように、溝部１００は、合口部２０には到達していないことが好ましい。溝部１００が合口部２０に到達しないことで、溝部１００に保持された潤滑油が、合口部２０から漏れ出ることが抑制できる点で好ましい。溝部１００の端部と合口部２０との間の距離Ｃは、０．２ｍｍ以上であることが好ましい。 FIG. 10 is a side view showing a configuration around the joint portion 20 of the piston ring 1. As shown in FIG. 10, it is preferable that the groove portion 100 does not reach the joint portion 20. Since the groove part 100 does not reach the joint part 20, it is preferable in that the lubricant retained in the groove part 100 can be prevented from leaking from the joint part 20. It is preferable that the distance C between the edge part of the groove part 100 and the abutment part 20 is 0.2 mm or more.
　図１１は、ピストンリング１の外周摺動面１０に形成される溝部１００の更に他の例を示す側面図である。図１１に示すように、溝部１００は、円周方向Ａ及び軸方向Ｂに沿って斜めに延在していてもよい。換言すれば、円周方向Ａ及び軸方向Ｂの両方に対して傾斜するように延在する構成としてもよい。また、ピストンリング１の外周摺動面１０には、上述した溝部１００が任意の組み合わせで形成されていてもよい。 FIG. 11 is a side view showing still another example of the groove portion 100 formed on the outer peripheral sliding surface 10 of the piston ring 1. As shown in FIG. 11, the groove portion 100 may extend obliquely along the circumferential direction A and the axial direction B. In other words, it may be configured to extend so as to be inclined with respect to both the circumferential direction A and the axial direction B. Moreover, the groove part 100 mentioned above may be formed in the outer periphery sliding surface 10 of the piston ring 1 by arbitrary combinations.
＜硬質皮膜＞
　ピストンリング１は、外周摺動面１０を被覆する硬質皮膜を備えていてもよい。ピストンリング１は、硬質皮膜を備えることで、耐摩耗性が向上し、溝部１００の断面形状をより維持することができる。硬質皮膜は、外周摺動面１０を層状に皮膜する硬質皮膜層として形成される。硬質皮膜はクロムめっき皮膜、イオンプレーティング皮膜、窒化皮膜、及び硬質炭素皮膜から選択される硬質皮膜であることが好ましい。硬質皮膜の厚さは、溝部１００を埋めて浅くしてしまうことがない程度であることが好ましい。詳細には、硬質皮膜の厚さは、イオンプレーティング皮膜では、６０μｍ未満であることが好ましく、４５μｍ未満であることがより好ましく、３０μｍ未満であることがさらに好ましい。一方、窒化皮膜の場合は、母材の表層に窒素が拡散して形成されるので溝部１００が覆われることはなく、硬質皮膜の厚さに制限はない。通常は、ビッカース硬さが７００ＨＶ０．１以上の拡散層の厚さが３０μｍ以上あることが好ましく、５０μｍ以上であればより好ましく、７０μｍ以上であればさらに好ましい。また、クロムめっき皮膜に関しては、溝部１００内で電場の打ち消しあいにより深さ方向に膜厚が薄くなり、開口径は少し狭くなっても、深さはほとんど変わらない。 <Hard coating>
The piston ring 1 may include a hard coating that covers the outer peripheral sliding surface 10. The piston ring 1 is provided with a hard coating, so that the wear resistance is improved and the cross-sectional shape of the groove portion 100 can be further maintained. The hard coating is formed as a hard coating layer that coats the outer peripheral sliding surface 10 in layers. The hard film is preferably a hard film selected from a chromium plating film, an ion plating film, a nitride film, and a hard carbon film. The thickness of the hard coating is preferably such that it does not fill the groove 100 and make it shallow. Specifically, the thickness of the hard film is preferably less than 60 μm, more preferably less than 45 μm, and even more preferably less than 30 μm in the case of an ion plating film. On the other hand, in the case of a nitride film, since nitrogen is diffused and formed in the surface layer of the base material, the groove 100 is not covered and the thickness of the hard film is not limited. Usually, the thickness of the diffusion layer having a Vickers hardness of 700 HV 0.1 or more is preferably 30 μm or more, more preferably 50 μm or more, and even more preferably 70 μm or more. Further, regarding the chromium plating film, the depth is hardly changed even if the film thickness is reduced in the depth direction due to the cancellation of the electric field in the groove portion 100 and the opening diameter is slightly reduced.
　硬質皮膜の厚さは、ガソリン車用ピストンリングでは、８０μｍ未満であることが好ましく、６０μｍ未満であることがより好ましく、４０μｍ未満であることがさらに好ましい。また、硬質皮膜の厚さは、ディーゼル車（特にヘビーデューティ）用ピストンリングでは１２０μｍ未満であることが好ましく、１００μｍ未満であることがより好ましく、８０μｍ未満であることがさらに好ましい。また、舶用ピストンリングでは３５０μｍ未満であることが好ましく、３２５μｍ未満であることがより好ましく、３００μｍ未満であることがさらに好ましい。なお、外周摺動面１０には、硬質皮膜層の形成後に溝部１００を形成してもよいし、溝部１００の形成後に硬質皮膜層を形成してもよい。 The thickness of the hard coating is preferably less than 80 μm, more preferably less than 60 μm, and even more preferably less than 40 μm in a gasoline vehicle piston ring. In addition, the thickness of the hard coating is preferably less than 120 μm, more preferably less than 100 μm, and even more preferably less than 80 μm in a piston ring for diesel vehicles (particularly heavy duty). In a marine piston ring, it is preferably less than 350 μm, more preferably less than 325 μm, and further preferably less than 300 μm. Note that the groove portion 100 may be formed on the outer peripheral sliding surface 10 after the hard coating layer is formed, or the hard coating layer may be formed after the groove portion 100 is formed.
＜溝部１００の形成方法＞
　以下、ピストンリング１の外周摺動面１０に溝部１００を形成する方法の一例について説明する。図１２は、ピストンリング１の外周摺動面１０に溝部１００を形成する様子を示す図である。図１３及び図１４は、ピストンリング１の外周摺動面１０に形成された溝部１００の一例を示す側面図及び軸方向Ｂに沿う断面図である。図１２に示すように、複数のピストンリング１を軸方向Ｂに沿って重ねた（スタックさせた）状態で、円周方向Ａに沿って螺旋状、すなわち、軸方向Ｂに対して一定の傾斜角をつけながら、溝を加工する。溝の加工には、レーザー加工、又はエッチング加工を用いる。これにより、例えば図１３（ａ）や図１３（ｂ）に示すような溝部１００が外周摺動面１０上に形成される。このように、複数のピストンリング１にまとめて溝部１００を形成することで、製造リードタイムが短縮され、コストを低減することができる。 <Method for Forming Groove 100>
Hereinafter, an example of a method for forming the groove 100 on the outer peripheral sliding surface 10 of the piston ring 1 will be described. FIG. 12 is a diagram illustrating a state in which the groove portion 100 is formed on the outer peripheral sliding surface 10 of the piston ring 1. FIGS. 13 and 14 are a side view and a cross-sectional view along the axial direction B showing an example of the groove 100 formed in the outer peripheral sliding surface 10 of the piston ring 1. As shown in FIG. 12, in a state where a plurality of piston rings 1 are stacked (stacked) along the axial direction B, they are spiral along the circumferential direction A, that is, have a constant inclination with respect to the axial direction B. Process the groove while making a corner. Laser processing or etching processing is used for processing the groove. Thereby, the groove part 100 as shown, for example in FIG. 13A or 13B is formed on the outer peripheral sliding surface 10. Thus, by forming the groove portion 100 in a plurality of piston rings 1, the manufacturing lead time is shortened, and the cost can be reduced.
　なお、溝部１００を形成する前に、ピストンリング１の軸方向Ｂに沿う両端部には、円周方向Ａに沿って、面取り部１１を形成しておくことが好ましい。溝部１００の軸方向Ｂに沿う幅Ｗ’は、０．３ｍｍ以下であることが好ましく、０．１ｍｍ以下であることがより好ましい。また、溝部１００の最深部１１０の深さＤ’は、１μｍ以下であることが好ましく、０．２μｍ以下であることがより好ましい。 In addition, it is preferable to form the chamfered portions 11 along the circumferential direction A at both end portions along the axial direction B of the piston ring 1 before forming the groove portion 100. The width W ′ along the axial direction B of the groove part 100 is preferably 0.3 mm or less, and more preferably 0.1 mm or less. Further, the depth D ′ of the deepest portion 110 of the groove portion 100 is preferably 1 μm or less, and more preferably 0.2 μm or less.
　本発明は、上述した実施形態の構成に限定されるものではなく、特許請求の範囲で記載された内容を逸脱しない範囲で、様々な構成により実現することが可能である。例えば、ピストンリング１は、バレルフェイス形状であるとして説明したが、バレルフェイス形状には限定されず、例えば、プレーン形状、テーパーフェイス形状等、他の任意の形状であってもよい。 The present invention is not limited to the configuration of the embodiment described above, and can be realized by various configurations without departing from the content described in the claims. For example, the piston ring 1 has been described as having a barrel face shape, but is not limited to the barrel face shape, and may be any other shape such as a plain shape or a tapered face shape.
　本発明は、内燃機関用のピストンリングに関する。 The present invention relates to a piston ring for an internal combustion engine.
　１　ピストンリング
　１０　外周摺動面
　１１　面取り部
　２０　合口部
　１００　溝部（凹部）
　１１０　最深部
　１２０　傾斜部
　１２１　湾曲部
　１２２　段差面
　１２３　縮径部
　１３０　頂部
　１４０　軸方向延在部
　２０１　非特許文献１のピストンリング
　２０２　非特許文献１のピストンリングの外周摺動面
　２０３　非特許文献１のシリンダ内壁
　Ａ　円周方向
　Ｂ　軸方向
　Ｃ　溝部の端部と合口部との間の距離
　Ｄ、Ｄ１、Ｄ２、Ｄ３、Ｄ’　溝部の最深部の深さ
　Ｗ、Ｗ’　溝部の軸方向に沿う幅
　Ｘ　非特許文献１のピストンリングの進行方向 DESCRIPTION OF SYMBOLS 1 Piston ring 10 Outer periphery sliding surface 11 Chamfering part 20 Joint part 100 Groove part (concave part)
DESCRIPTION OF SYMBOLS 110 Deepest part 120 Inclined part 121 Curved part 122 Step surface 123 Reduced diameter part 130 Top part 140 Axial extension part 201 Piston ring of nonpatent literature 1 202 Outer peripheral sliding surface of piston ring of nonpatent literature 203 Inner wall of cylinder A A Circumferential direction B Axial direction C Distance between end of groove and joint D, D1, D2, D3, D 'Depth of deepest part of groove W, W' Along the axial direction of groove Width X Traveling direction of piston ring of Non-Patent Document 1

Claims (11)

  1. 　外周摺動面に凹部が形成されたピストンリングであって、
    　前記凹部は、外径が最も小さい最深部と、前記最深部に向かって漸次縮径する傾斜部と、を有することを特徴とするピストンリング。     A piston ring having a recess formed on the outer peripheral sliding surface,
    The said recessed part has the deepest part with the smallest outer diameter, and the inclination part which diameter-reduces gradually toward the said deepest part, The piston ring characterized by the above-mentioned.
  2. 　前記傾斜部は、前記最深部と連続することを特徴とする、請求項１に記載のピストンリング。 The piston ring according to claim 1, wherein the inclined portion is continuous with the deepest portion.
  3. 　前記傾斜部は、凸状となる湾曲部を含むことを特徴とする、請求項１又は２に記載のピストンリング。 3. The piston ring according to claim 1, wherein the inclined portion includes a curved portion that is convex.
  4. 　前記凹部は、外径が周囲よりも大きい頂部を更に有し、
    　前記傾斜部は、前記頂部に向かって漸次拡径することを特徴とする、請求項１から３のいずれか一項に記載のピストンリング。     The recess further has a top portion whose outer diameter is larger than the surroundings,
    The piston ring according to any one of claims 1 to 3, wherein the inclined portion gradually increases in diameter toward the top portion.
  5. 　前記凹部は、複数形成され、
    　前記複数の凹部は、前記最深部の外径がそれぞれ異なる２以上の凹部を含むことを特徴とする、請求項１から４のいずれか一項に記載のピストンリング。     A plurality of the recesses are formed,
    The piston ring according to any one of claims 1 to 4, wherein the plurality of recesses include two or more recesses having different outer diameters of the deepest part.
  6. 　前記凹部は、所定の方向に沿って延在する溝部であることを特徴とする、請求項１から５のいずれか一項に記載のピストンリング。 The piston ring according to any one of claims 1 to 5, wherein the concave portion is a groove portion extending along a predetermined direction.
  7. 　前記溝部は、円周方向に沿って延在することを特徴とする、請求項６に記載のピストンリング。 The piston ring according to claim 6, wherein the groove portion extends along a circumferential direction.
  8. 　前記溝部は複数形成され、
    　前記複数の溝部は、円周方向に沿って配置されていることを特徴とする、請求項６又は７に記載のピストンリング。     A plurality of the groove portions are formed,
    The piston ring according to claim 6 or 7, wherein the plurality of grooves are arranged along a circumferential direction.
  9. 　前記溝部は、周囲よりも軸方向に延在する軸方向延在部を更に有することを特徴とする、請求項７又は８に記載のピストンリング。 The piston ring according to claim 7 or 8, wherein the groove portion further includes an axially extending portion extending in an axial direction from the periphery.
  10. 　前記凹部は、合口部には到達していないことを特徴とする、請求項１から９のいずれか一項に記載のピストンリング。 The piston ring according to any one of claims 1 to 9, wherein the concave portion does not reach the joint portion.
  11. 　前記外周摺動面を被覆する硬質皮膜を備えることを特徴とする、請求項１から１０のいずれか一項に記載のピストンリング。 The piston ring according to any one of claims 1 to 10, further comprising a hard coating that covers the outer peripheral sliding surface.
PCT/JP2018/007892 2018-03-01 2018-03-01 Piston ring WO2019167241A1 (en)

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Application Number Priority Date Filing Date Title
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Application Number Priority Date Filing Date Title
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS476483Y1 (en) * 1969-02-26 1972-03-07
JPS5928050A (en) * 1982-07-19 1984-02-14 ゲブリユ−ダ−・ズルツア−・アクチエンゲゼルシヤフト Reciprocating internal combustion engine with split piston ring
JPH02119488A (en) * 1988-10-28 1990-05-07 Fuji Photo Film Co Ltd Still picture video telephone with printer
JPH05340473A (en) * 1992-06-01 1993-12-21 Nippon Steel Corp Piston ring and machining method thereof
JP2010236649A (en) * 2009-03-31 2010-10-21 Nippon Piston Ring Co Ltd Combination of piston ring and cylinder or cylinder liner, and piston ring used in the same

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS476483Y1 (en) * 1969-02-26 1972-03-07
JPS5928050A (en) * 1982-07-19 1984-02-14 ゲブリユ−ダ−・ズルツア−・アクチエンゲゼルシヤフト Reciprocating internal combustion engine with split piston ring
JPH02119488A (en) * 1988-10-28 1990-05-07 Fuji Photo Film Co Ltd Still picture video telephone with printer
JPH05340473A (en) * 1992-06-01 1993-12-21 Nippon Steel Corp Piston ring and machining method thereof
JP2010236649A (en) * 2009-03-31 2010-10-21 Nippon Piston Ring Co Ltd Combination of piston ring and cylinder or cylinder liner, and piston ring used in the same

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