Piston ring set

Abstract

A piston ring set of one side surface has a top ring and an oil ring, and is inserted into a cylinder bore of an internal combustion engine, wherein the top ring has a ring-shaped main body portion including an inner peripheral surface, an outer peripheral surface, one side surface and another side surface which are substantially orthogonal to the inner peripheral surface, and a first opening end portion and a second opening end portion which face each other to form an opening portion, and the oil ring has a pair of rails which face each other, and an opening flow passage area of the top ring is 0.1 mm 2 Hereinafter, the outer peripheral followability coefficient of the oil ring is 0.3 or more.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a piston ring set. BACKGROUND

[0002] A piston ring set for an internal combustion engine of an automobile or the like is, for example, fitted to a ring groove of an outer peripheral surface of a piston. The piston ring set fitted to the ring groove slides on an inner wall of a cylinder bore. The piston ring set maintains air tightness between a combustion chamber and a crank chamber, and reduces oil consumption. As such a piston ring set, a piston ring set described in Patent Literature 1 is known.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2013-231481 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] In order to achieve improvement in fuel economy of an internal combustion engine or the like, it is required to reduce blow-by gas leaking to a crank chamber. However, with the reduction in blow-by gas, oil consumption and friction increase, and thus it is difficult to reduce all of the blow-by gas, the oil consumption, and the friction well. An aspect of the present disclosure provides a piston ring set capable of reducing the blow-by gas, the oil consumption, and the friction respectively.

[0008] MEANS FOR SOLVING THE PROBLEMS

[0009] The piston ring set of the aspect of the present disclosure includes a top ring and an oil ring, and is inserted into a cylinder bore of an internal combustion engine in a state of being attached to a piston, wherein the top ring has a ring-shaped main body portion including an inner peripheral surface, an outer peripheral surface, a first side surface and a second side surface which are substantially orthogonal to the inner peripheral surface, and a first open end portion and a second open end portion which face each other to form an opening portion, the oil ring has a pair of rails which face each other, and an open passage area of the top ring is 0.1 mm 2 Hereinafter, the outer peripheral followability coefficient of the oil ring is 0.3 or more.

[0010] In the piston ring set, the open passage area of the top ring is 0.1 mm 2 Hereinafter, and the outer peripheral followability coefficient of the oil ring is 0.3 or more. With the open passage area of 0.1 mm 2The blow-by can be reduced. However, as the blow-by is reduced, the amount of oil blown by the blow-by is reduced. Thus, there is a tendency that the excess oil adhering to the inner surface of the cylinder bore increases, and there is a tendency that the friction of the top ring also increases. Here, the outer peripheral followability coefficient of the oil ring is 0.3 or more, and the oil ring well follows the inner surface of the cylinder bore. Thus, the excess oil adhering to the inner surface of the cylinder bore caused by the top ring is well scraped off by the oil ring. Therefore, in the case where the above piston ring set including both the above top ring and the above oil ring is used, the oil consumption amount reduced due to the above oil ring exceeds the oil consumption amount increased due to the above top ring. That is, by using the above piston ring set, the blow-by, the oil consumption amount, and the friction can be reduced respectively. In particular, the friction of the above piston ring set including both the above top ring and the above oil ring can be reduced equally to the friction of the piston ring set including the above oil ring.

[0011] Effects of Invention

[0012] According to an aspect of the present disclosure, a piston ring set capable of reducing a blow-by, an oil consumption amount, and a friction respectively can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a perspective view of a piston ring set of an embodiment.

[0014] Figure 2 is a cross-sectional view of an oil ring of an embodiment.

[0015] Figure 3 (a) of is a cross-sectional view showing an example of a barrel surface shape, Figure 3 (b) of is a cross-sectional view showing an example of a taper surface shape, Figure 3 (c) of is a cross-sectional view showing an example of a bullet surface shape.

[0016] Figure 4 is a main part enlarged schematic view showing a main part of blow-by gas leaking from a top ring.

[0017] Figure 5 (a) of is a main part enlarged schematic view of an example of an opening portion of a top ring, Figure 5 (b) of is a main part enlarged schematic view of an example of an outer peripheral lower surface chamfer portion of a top ring.

[0018] Figure 6 (a) to (c) of are graphs showing experimental results of comparative examples, Figure 6 (d) of is a graph showing experimental results of an embodiment.

[0019] Figure 7 (a) and (b) of are graphs showing experimental results of an embodiment.

[0020] Figure 8(a) of FIG. 1 is a graph showing experimental results of a comparative example, Figure 8 (b) to (d) of FIG. 1 are graphs showing experimental results of examples.

[0021] Figure 9 (a) and (b) of FIG. 1 are graphs showing experimental results of a comparative example, Figure 9 (c) to (f) of FIG. 1 are graphs showing experimental results of examples. DETAILED DESCRIPTION

[0022] [Outline of Embodiments of the Present Disclosure]

[0023] First, an outline of the embodiments of the present disclosure will be described.

[0024] (1) A piston ring set having a top ring and an oil ring, and being inserted into a cylinder bore of an internal combustion engine in a state of being fitted to a piston, wherein the top ring has a ring-shaped main body portion including an inner peripheral surface, an outer peripheral surface, a first side surface and a second side surface which are substantially orthogonal to the inner peripheral surface, and a first opening end portion and a second opening end portion which face each other to form an opening portion, the oil ring has a pair of rails which face each other, and an opening flow passage area of the top ring is 0.1 mm 2 Hereinafter, the outer peripheral followability coefficient of the oil ring is 0.3 or more.

[0025] (2) The piston ring set according to (1), wherein the outer peripheral followability coefficient of the oil ring is 0.8 or less.

[0026] (3) The piston ring set according to (1) or (2), wherein a first opening chamfer surface, a second opening chamfer surface, and an outer peripheral lower surface chamfer surface are provided in the main body portion, the first opening chamfer surface is located between the first opening end portion and the outer peripheral surface, the second opening chamfer surface is located between the second opening end portion and the outer peripheral surface, and the outer peripheral lower surface chamfer surface is located between one of the first side surface and the second side surface and the outer peripheral surface,

[0027] when the top ring and the oil ring are inserted into the cylinder bore in a state of being fitted to the piston,

[0028] a first opening chamfer portion is formed between the inner surface of the cylinder bore and the first opening chamfer surface, a second opening chamfer portion is formed between the inner surface and the second opening chamfer surface, and an outer peripheral lower surface chamfer portion is formed between the inner surface and the outer peripheral lower surface chamfer surface,

[0029] With the gap between the first opening end and the second opening end set as s1, the gap between the outer surface of the piston and the inner surface of the cylinder bore set as g1, the correction coefficient based on the inner diameter of the cylinder bore set as f, the size of the chamfer of the first opening set as C1, the size of the chamfer of the second opening set as C2, and the size of the chamfer of the lower outer circumference set as C3, the opening flow area is expressed as s1×g1×f+C1+C2+2×C3. With the tension of the oil ring set as Ft, the inner diameter of the cylinder bore set as d1, the thickness of each of the pair of tracks along the radial direction of the cylinder bore set as a1, the elastic modulus of the material constituting each pair of tracks set as E, and the width of each of the pair of tracks along the axial direction of the cylinder bore set as h12, the peripheral following coefficient is expressed as 3 / 2×Ft×(d1-a1). 2 / (E×h12×a1 3 ).

[0030] (4) The piston ring assembly according to (3), wherein the radial dimension of the chamfered portion of the outer peripheral lower surface is smaller than the axial dimension of the chamfered portion of the outer peripheral lower surface.

[0031] (5) The piston ring assembly according to any one of (1) to (4), wherein the piston ring assembly further comprises a second ring having an annular second body portion, the second body portion comprising a third opening end and a fourth opening end that are opposite each other to form a second opening, the gap between the third opening end and the fourth opening end being 1.8 or less relative to the gap between the first opening end and the second opening end.

[0032] (6) The piston ring assembly according to any one of (1) to (5), wherein each outer peripheral surface of the pair of tracks has either a conical shape or a bullet shape.

[0033] [Examples of embodiments of this disclosure]

[0034] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements are labeled with the same reference numerals, and repeated descriptions are omitted where appropriate.

[0035] Figure 1 This is a perspective view of the piston ring assembly in the embodiment. Figure 1 The top ring 10, second ring 20, and oil ring 30 shown constitute piston ring assembly 1. Piston ring assembly 1 is, for example, fitted into the ring grooves on the outer circumferential surface of the piston in an internal combustion engine of an automobile. When fitted onto the piston, piston ring assembly 1 is inserted into the cylinder bore of the internal combustion engine. By sliding relative to the inner wall of the cylinder bore, piston ring assembly 1 serves to seal the gas between the combustion chamber side and the crankshaft chamber side, and also reduces oil consumption.

[0036] The top ring 10 has a ring-shaped main body portion 11. The main body portion 11 includes a side surface (first side surface) 11a, a side surface (second side surface) 11b, an inner peripheral surface 11c, an outer peripheral surface 11d, an open end portion (first open end portion) 13, and an open end portion (second open end portion) 14. The side surfaces 11a, 11b are substantially orthogonal to the inner peripheral surface 11c. The open end portions 13, 14 are opposed to each other to form an opening portion 15. In the following description, a direction connecting the side surface 11a and the side surface 11b is referred to as a width direction of the top ring 10, and a direction connecting the inner peripheral surface 11c and the outer peripheral surface 11d is referred to as a thickness direction of the top ring 10. The width direction of the top ring 10 corresponds to an axial direction D1 of a cylinder bore into which the piston ring set 1 is inserted. The thickness direction of the top ring 10 corresponds to a radial direction D2 of the cylinder bore into which the piston ring set 1 is inserted. A direction in which the main body portion 11 extends in a ring shape corresponds to a circumferential direction D3 of the cylinder bore. Figure 1 In the example, the side surface 11a is an upper surface of the main body portion 11, and the side surface 11b is a lower surface of the main body portion 11. The open end portions 13, 14 are opposed to each other to form the opening portion 15. In the following description, a direction connecting the side surface 11a and the side surface 11b is referred to as a width direction of the top ring 10, and a direction connecting the inner peripheral surface 11c and the outer peripheral surface 11d is referred to as a thickness direction of the top ring 10. The width direction of the top ring 10 corresponds to an axial direction D1 of a cylinder bore into which the piston ring set 1 is inserted. The thickness direction of the top ring 10 corresponds to a radial direction D2 of the cylinder bore into which the piston ring set 1 is inserted. A direction in which the main body portion 11 extends in a ring shape corresponds to a circumferential direction D3 of the cylinder bore.

[0037] The main body portion 11 has a substantially rectangular cross section in which the thickness direction is a long side and the width direction is a short side. The main body portion 11 is formed, for example, using cast iron or steel containing a plurality of metal elements, in a manner to have sufficient strength, heat resistance, and elasticity.

[0038] The surface of the main body portion 11 can be subjected to surface modification to form a hard film. The hard film is, for example, a physical vapor deposition film (PVD film) formed using a physical vapor deposition method (PVD method). Thus, the hard film can be formed with sufficient hardness. The hard film is an ion plating film or a diamond-like carbon film containing at least one of titanium (Ti) and chromium (Cr) and at least one of carbon (C), nitrogen (N), and oxygen. As specific examples, the hard film is a titanium nitride film, a chromium nitride film, a titanium carbonitride film, a chromium carbonitride film, a chromium oxynitride film, a chromium film, or a titanium film. From the viewpoint of wear resistance and scratch resistance, the hard film can be a chromium nitride film. The hard film can be a laminate, and for example, can contain a chromium nitride film and a diamond-like carbon film.

[0039] The opening portion 15 is a gap in which a portion of the main body portion 11 is cut off. The open end portions 13, 14 are portions that become free ends of the main body portion 11, respectively. The size of the opening portion 15 is represented as a gap s1 between the open end portions 13, 14 in a state in which the top ring 10 is inserted into the cylinder bore at normal temperature.

[0040] The second ring 20 has a ring-shaped main body portion 21. The main body portion 21 includes a side surface 21a, a side surface 21b, an inner peripheral surface 21c, an outer peripheral surface 21d, an open end portion (third open end portion) 23, and an open end portion (fourth open end portion) 24. The side surfaces 21a, 21b are substantially orthogonal to the inner peripheral surface 21c. The open end portions 23, 24 are opposed to each other to form an opening portion 25. In the following description, a direction connecting the side surface 21a and the side surface 21b is referred to as a width direction of the second ring 20, and a direction connecting the inner peripheral surface 21c and the outer peripheral surface 21d is referred to as a thickness direction of the second ring 20. The width direction of the second ring 20 corresponds to an axial direction D1 of a cylinder bore into which the piston ring set 1 is inserted. The thickness direction of the second ring 20 corresponds to a radial direction D2 of the cylinder bore into which the piston ring set 1 is inserted. A direction in which the main body portion 21 extends in a ring shape corresponds to a circumferential direction D3 of the cylinder bore. Figure 1In this example, side 21a is the upper surface of the main body 21, and side 21b is the lower surface of the main body 21. Opening ends 23 and 24 face each other to form an opening (second opening) 25. The main body 21 may also be formed of the same material as the top ring 10. A hard film may also be formed on the surface of the main body 21 by performing surface modification similar to that on the top ring 10.

[0041] The opening 25 is a gap formed by cutting off a portion of the main body 21. The opening ends 23 and 24 are the free ends of the main body 21, respectively. The size of the opening 25 is expressed as the gap s2 between the openings 23 and 24 at room temperature with the second ring 20 inserted into the cylinder bore. Hereinafter, the ratio of gap s2 to gap s1 (s2 / s1) is referred to as the "S1 ratio". In this embodiment, the S1 ratio is 1.8 or less. The S1 ratio may also be 1.5 or less. The S1 ratio may also be 1.4 or less.

[0042] The oil ring 30 has a pair of tracks 31 facing each other and a spacer outer expansion ring 32. The pair of tracks 31 are the side tracks of the oil ring 30. The spacer outer expansion ring 32 is disposed between the pair of tracks 31. In this embodiment, the pair of tracks 31 and the spacer outer expansion ring 32 constitute three oil rings 30. In addition, an opening is formed in each pair of tracks 31.

[0043] Figure 2 This is a cross-sectional view of the oil ring in the embodiment. Figure 2 This represents the structure of the oil ring 30 in a section orthogonal to the circumferential direction D3. For example... Figure 2 As shown, each track 31 has a side surface 31a, a side surface 31b, an inner circumferential surface 31c, and an outer circumferential surface 31d. Side surfaces 31a and 31b constitute the two ends of each track 31 along the axial direction D1. Figure 2 In the example, side 31a is the outward-facing surface, and side 31b is the surface facing the spaced outer expansion ring 32. Each track 31 can also be formed of the same material as the top ring 10. Details regarding the shape of the outer peripheral surface 31d will be described later.

[0044] The peripheral following coefficient k of the oil ring 30 is expressed by the following mathematical formula.

[0045] k = 3 / 2 × Ft × (d1 - a1) 2 / (E×h12×a1 3 )

[0046] Ft is the tension of the oil ring 30. The tension Ft of the oil ring 30 is not particularly limited. From the viewpoint of reducing friction, the tension Ft can be 20 N or less, 15 N or less, or 12 N or less. d1 is the inner diameter of the cylinder bore into which the oil ring 30 is inserted. a1 is the thickness of each track 31 along the radial direction D2. E is the elastic modulus of the material constituting each track 31. h12 is the width of each track 31 along the axial direction D1. The peripheral following coefficient k of the oil ring 30 is 0.3 or more. The peripheral following coefficient k of the oil ring 30 can be 0.4 or more, or 0.5 or more. In this embodiment, the peripheral following coefficient k of the oil ring 30 is 0.3 or more and 0.8 or less.

[0047] By keeping the peripheral following coefficient k below 0.8, it is difficult to increase oil consumption due to deformation of track 31. From the perspective of balancing low tension Ft and high peripheral following coefficient k, thickness a1 can be below 1.65 mm or below, or below 1.50 mm. There is no particular limitation on the lower limit of thickness a1. From the perspective of the rigidity of track 31, the lower limit of thickness a1 can also be above 1.30 mm.

[0048] Figure 3 (a) to (c) are cross-sectional views showing the detailed shape of the outer peripheral surface 31d. Each track 31 may also have a barrel shape. Figure 3 (a) is a cross-sectional view of an example of a track with a barrel-shaped surface. For example... Figure 3 As shown in (a), the outer peripheral surface 31d includes a sliding surface B1 having a first radius of curvature and a pair of edge surfaces B2 having a second radius of curvature. The sliding surface B1 is curved in a manner that protrudes toward the cylinder bore into which the oil supply ring 30 is inserted. The sliding surface B1 is sandwiched between the pair of edge surfaces B2 in the axial direction D1. One edge surface B2 is located between the side surface 31a and the sliding surface B1, and connects the side surface 31a and the sliding surface B1 to each other. The other edge surface B2 is located between the side surface 31b and the sliding surface B1, and connects the side surface 31b and the sliding surface B1 to each other. The first radius of curvature is smaller than the second radius of curvature. The length of the sliding surface B1 along the axial direction D1 is denoted as b1. The length of the sliding surface B1 along the radial direction D2 is denoted as b2. In the barrel shape, the shape of the outer peripheral surface 31d can be a shape that is symmetrical about the centerline in the axial direction D1 of the track 31, or it can be an asymmetrical shape.

[0049] Each track 31 can also have a conical shape. Figure 3 (b) is a cross-sectional view of an example of a conical track. For example... Figure 3As shown in (b), the outer peripheral surface 31d includes an inclined surface T1 and a sliding surface T2 extending linearly in an inclined manner relative to the axial direction D1. The inclined surface T1 is inclined in such a way that it protrudes toward the cylinder bore into which the oil supply ring 30 is inserted as the distance between it and the side surface 31b decreases. The sliding surface T2 is curved in such a way that it protrudes toward the cylinder bore into which the oil supply ring 30 is inserted. The inclination of the inclined surface T1 relative to the axial direction D1 is denoted as t1. The length of the sliding surface T2 along the radial direction D2 is denoted as t2. The length along the axial direction D1 between the most protruding part of the sliding surface T2 and the side surface 31b is denoted as t3. In the conical shape, the shape of the outer peripheral surface 31d is asymmetrical with respect to the centerline on the axial direction D1 of the track 31.

[0050] Each track 31 can also have a bullet-shaped surface. Figure 3 (c) is a cross-sectional view of an example of a trajectory representing the shape of a bullet's surface. For example... Figure 3 As shown in (c), the outer peripheral surface 31d includes a sliding surface BT1 with a third radius of curvature and a pair of straight edge surfaces BT2. The sliding surface BT1 is curved to protrude toward the cylinder bore into which the oil supply ring 30 is inserted. The sliding surface BT1 is sandwiched between the pair of edge surfaces BT2 in the axial direction D1. The pair of edge surfaces BT2 connect the side surfaces 31a, 31b to the sliding surface BT1. The length of the sliding surface BT1 along the axial direction D1 is denoted as bt1. The length of the sliding surface BT1 along the radial direction D2 is denoted as bt2.

[0051] Figure 4 This is an enlarged schematic diagram showing the main part of the gas leaking from the top ring. Figure 5 (a) is an enlarged schematic diagram of the main part of an example of the opening of the top ring. Figure 5 (b) is an enlarged schematic diagram of the main part of an example of the chamfered portion of the lower outer surface of the top ring. For example... Figure 4 and Figure 5 As shown, the main body 11 includes chamfered surfaces 13a, 14a and chamfered surface 11e.

[0052] Chamfered surface 13a is a surface located between the opening end 13 and the outer peripheral surface 11d, connecting the opening end 13 and the outer peripheral surface 11d (first opening chamfered surface). Chamfered surface 13a is formed by chamfering the corner formed by the opening end 13 and the outer peripheral surface 11d. An opening chamfer portion (first opening chamfer portion) 16 is formed between chamfered surface 13a and the inner surface 3a of the cylinder bore 3. The opening chamfer portion 16 is a gap corresponding to the portion removed from the main body portion 11 by chamfering the corner formed by the opening end 13 and the outer peripheral surface 11d. Chamfered surface 14a is a surface located between the opening end 14 and the outer peripheral surface 11d, connecting the opening end 14 and the outer peripheral surface 11d (second opening chamfered surface). Chamfered surface 14a is a surface formed by chamfering the corner formed by the opening end 14 and the outer peripheral surface 11d. The chamfered opening 17 is a gap corresponding to the portion removed from the main body 11 by the chamfer formed by the corner created by the opening end 14 and the outer peripheral surface 11d. The chamfered opening (second chamfered opening) 17 is formed between the chamfered surface 14a and the inner surface 3a of the cylinder bore 3. The area of ​​the chamfered opening 16 as observed along the axial direction D1 is denoted as C1. The area of ​​the chamfered opening 17 as observed along the axial direction D1 is denoted as C2. The areas C1 and C2 can be measured or obtained using known methods.

[0053] like Figure 4 As shown, in this embodiment, chamfered surfaces 13a and 14a are formed by chamfering the corners formed by the open ends 13 and 14 and the outer peripheral surface 11d at a 45-degree angle (C). Therefore, if the chamfer dimension of chamfered surface 13a is set as x, then the area C1 is expressed as C1 = x. 2 / 2. Similarly, if the chamfer dimension of chamfered surface 14a is set as y, then the area C2 is expressed as C2=y. 2 / 2.

[0054] The chamfered surface 11e is a surface located between the side surface 11b and the outer peripheral surface 11d, connecting the side surface 11b and the outer peripheral surface 11d (outer peripheral lower surface chamfered surface). The chamfered surface 11e is formed by chamfering the corner formed by the outer peripheral surface 11d and the side surface 11b. An outer peripheral lower surface chamfered portion 18 is formed between the chamfered surface 11e and the inner surface 3a of the cylinder bore 3. The outer peripheral lower surface chamfered portion 18 is the gap corresponding to the portion removed from the main body portion 11 by chamfering the corner formed by the side surface 11b and the outer peripheral surface 11d. The area of ​​the outer peripheral lower surface chamfered portion 18 as observed along the circumferential direction D3 is denoted as C3. The chamfered surface 11e is a surface formed by chamfering the corner formed by the outer peripheral surface 11d and the side surface 11b at any angle (e.g., 45 degrees), or a surface formed by chamfering the corner with an R-shape. Figure 5As shown in (b), in this embodiment, the chamfered surface 11e is a surface formed by chamfering the corner formed by the outer peripheral surface 11d and the side surface 11b at an arbitrary angle. In this case, if the dimension of the chamfered surface 11e along the axial direction D1 is set as zh and the dimension of the chamfered surface 11e along the radial direction D2 is set as za, then the area C3 is expressed as C3 = zh × za / 2.

[0055] The radial dimension za of the chamfered portion 18 on the outer peripheral lower surface along D2 can also be smaller than the axial dimension zh of the chamfered portion 18 on the outer peripheral lower surface along D1. When dimension za is smaller than dimension zh, oil is less likely to excessively penetrate the sliding surface B1. As a result, the oil scraping performance of the top ring 10 is improved. Dimension za can be less than 0.12 mm, less than 0.09 mm, or less than 0.06 mm. There is no particular limitation on the lower limit of dimension za. From the viewpoint of preventing the rupture of the hard film, dimension za can also be greater than 0.02 mm. Even when the chamfered surface 11e is an R-shaped chamfer, dimension za can be smaller than dimension zh.

[0056] like Figure 4 As shown, the leakage gas G from the top ring 10 passes through at least one of the opening 15, the chamfered opening portions 16 and 17, and the chamfered outer peripheral surface portion 18. The leakage gas G passing through the chamfered outer peripheral surface portion 18 includes leakage gas G1 passing through the chamfered outer peripheral surface portion 18a adjacent to the opening end 13 and leakage gas G2 passing through the chamfered outer peripheral surface portion 18b adjacent to the opening end 14. In this embodiment, the areas of the chamfered outer peripheral surface portion 18a and the chamfered outer peripheral surface portion 18b observed along the circumferential direction D3 are both equal to the area C3. Furthermore, the areas of the chamfered outer peripheral surface portion 18a and the chamfered outer peripheral surface portion 18b observed along the circumferential direction D3 may also be different from each other.

[0057] The flow rate of the blow-by gas G varies according to the opening flow area I. The opening flow area I is determined based on the opening 15, the chamfered opening 16, 17, and the chamfered outer circumferential lower surface 18a, 18b of the top ring 10 inserted into the cylinder bore 3 when installed with the piston 2. The opening flow area I is the sum of the area of ​​the opening 15 observed along the axial direction D1, the area C1 of the chamfered opening 16 observed along the axial direction D1, the area C2 of the chamfered opening 17 observed along the axial direction D1, the area C3 of the chamfered outer circumferential lower surface 18a adjacent to the opening end 13 observed along the circumferential direction D3, and the area C3 of the chamfered outer circumferential lower surface 18b adjacent to the opening end 14.

[0058] like Figure 5As shown in (a), the gap between the outer surface 2a of the piston 2 to which the top ring 10 is mounted and the inner surface 3a of the cylinder bore 3 into which the top ring 10 is inserted is denoted as g1. Specifically, g1 is the value of (inner diameter of cylinder bore 3 - diameter of the upper end of the second groove ridge of piston 2) / 2. g1 can also be determined in the range of 0.05 mm or more and 0.5 mm or less.

[0059] In this embodiment, the area of ​​the opening 15 when the top ring 10 is inserted into the cylinder bore 3 while mounted on the piston 2, viewed along the axial direction D1, is expressed as s1×g1. In this case, the gap s1 between the opening ends 13 and 14 is proportional to the diameter of the top ring 10, therefore a correction factor f is introduced. The correction factor f is the ratio of the inner diameter of the reference cylinder bore to the inner diameter of the cylinder bore 3 into which the top ring 10 is inserted. If the inner diameter of the reference cylinder bore is set to X, and the inner diameter of the cylinder bore 3 is set to Y, then the correction factor f is expressed as f=X / Y. In this embodiment, the inner diameter of the reference cylinder bore is set to φ80. Therefore, the correction factor f is expressed as f=80 / Y. The area of ​​the opening 15 with the correction factor f introduced is expressed as s1×g1×f. Therefore, the opening flow area I is expressed by the following mathematical formula. In this embodiment, the opening flow area I of the top ring 10 is 0.1 mm. 2 The opening flow area I of the top ring 10 can also be 0.07 mm. 2 The following applies: The opening flow area I can be 0.05 mm². 2 The following can also be 0.03mm 2 the following.

[0060] I = s1 × g1 × f + C1 + C2 + 2 × C3

[0061] Furthermore, when the area C31 of the chamfered portion 18a of the outer periphery observed along the circumferential direction D3 is different from the area C32 of the chamfered portion 18b of the outer periphery observed along the circumferential direction D3, 2×C3 is replaced by the sum of C31 and C32.

[0062] In the piston ring assembly 1 described above, the opening flow area of ​​the top ring 10 is 0.1 mm. 2 Below this, and the outer circumferential following coefficient of the oil ring 30 is 0.3 or higher. The flow area through the opening is 0.1 mm. 2The following can reduce blow-by gas G. However, as blow-by gas G decreases, the amount of oil blown off by blow-by gas G also decreases. As a result, there is a tendency for excess oil adhering to the inner surface 3a of the cylinder bore 3 to increase, and there is also a tendency for the friction of the top ring 10 to increase. Here, with the outer circumferential following coefficient of the oil ring 30 being 0.3 or higher, the oil ring 30 follows the inner surface 3a of the cylinder bore 3 well. Therefore, the excess oil adhering to the inner surface 3a of the cylinder bore 3 caused by the top ring 10 is effectively scraped off by the oil ring 30. Therefore, when using the piston ring assembly 1 including both the top ring 10 and the oil ring 30, the reduction in oil consumption due to the oil ring 30 exceeds the increase in oil consumption due to the top ring 10. That is, by using the piston ring assembly 1, blow-by gas G, oil consumption, and friction can be reduced respectively. In particular, the friction of the piston ring assembly 1 including both the top ring 10 and the oil ring 30 can be reduced as much as the friction of the piston ring assembly including the oil ring 30.

[0063] With a large opening flow area (greater than 0.1 mm) 2 In a piston ring assembly consisting of a top ring and a second ring with a small opening gap, the S1 ratio decreases. In this case, the pressure of the second groove ridge increases due to blow-by gas (G), leading to a tendency for the top ring to chatter. When top ring chatter occurs, the amount of blow-by gas (G), oil consumption, and friction increase. Piston ring assembly 1 passes through a flow area with a small opening (0.1 mm). 2 The combination of the top ring 10 (with a small opening gap) and the second ring 20 (with a small opening gap) has a synergistic effect in suppressing the chattering of the top ring 10, even when the S1 ratio is less than 1.8. As a result, the piston ring assembly 1 can effectively reduce blow-by, oil consumption, and friction.

[0064] The present disclosure has been described in detail above based on its embodiments. However, the present disclosure is not limited to the above embodiments. Various modifications can be made to the present disclosure without departing from its spirit.

[0065] The oil ring is not limited to three oil rings. It can also be a two-piece oil ring. The peripheral conformity coefficient of the two-piece oil ring is determined based on the cross-sectional shape of the two oil rings. The chamfered portion of the opening and the chamfered portion of the lower outer peripheral surface are not each limited to a C-shaped chamfer. The chamfered portion of the opening and the chamfered portion of the lower outer peripheral surface can also be R-shaped chamfers. The S1 ratio is not limited to 1.8 or less.

[0066] The outer circumferential surface of the top ring can be any of the following shapes: barrel shape, eccentric barrel shape, and conical shape. The cross-sectional shape of the second ring can also be any of the following: scraper, balancing scraper, rapier, and balancing rapier. The outer circumferential surface of the second ring can also be any of the following: conical shape, barrel shape, and eccentric barrel shape. The outer circumferential surface of the oil ring track can also be any of the following: conical shape, barrel shape, eccentric barrel shape, and bullet shape. The oil ring can also have a surface pressure of 0.35 MPa or higher and a barrel-shaped outer circumferential surface.

[0067] Example

[0068] The present disclosure is illustrated in more detail by way of the following examples, but the present disclosure is not limited to these examples.

[0069] Figures 6-9 These are graphs representing the experimental results of comparative examples or exemplary cases. Figures 6-9 In the figures, for internal combustion engines using the piston ring assemblies of the comparative and exemplary examples, fuel consumption, blow-by volume, and friction were measured. The cylinder bore inner diameter of this internal combustion engine is φ73. Fuel consumption was measured under various operating conditions: "low speed, high load" and "mode conditions". In "low speed, high load", fuel consumption was measured under operating conditions of acceleration from a standstill (idle speed) and acceleration on a slope (for example, 1000~2000 rpm × 100% load operation). In "mode conditions", fuel consumption was measured under operating conditions assuming urban operation, repeatedly cycling through engine stop, idle, acceleration, deceleration, constant speed, acceleration, and deceleration.

[0070] exist Figures 6-9 In the experimental results of the comparative examples and embodiments shown respectively, the oil consumption per hour (grams) was measured as "low rotation high load oil consumption [g / hr]" and "mode condition oil consumption [g / hr]", the amount of gas leakage per minute (liters) was measured as "low rotation high load gas leakage [L / min]", and the magnitude of friction (watts) was measured as "mode condition friction [W]". The experimental results of the comparative examples and embodiments are expressed in terms of... Figure 6 The relative evaluation value shown in (a) is based on Comparative Example 1. That is, the experimental results of “low rotation high load oil consumption”, “mode condition oil consumption”, “low rotation high load leakage gas” and “mode condition friction” in Comparative Example 1 are each set to 1.00, and the magnitude of the experimental results of the Comparative Example and the Example is expressed as a proportion relative to the experimental result of Comparative Example 1 of 1.00.

[0071] exist Figures 6-9In the experimental results of the comparative examples and embodiments shown, "low rotation high load oil consumption" is represented by the chart A located at the left end, "mode condition oil consumption" is represented by the chart B located second from the left end, "low rotation high load leakage gas" is represented by the chart C located third from the left end, and "mode condition friction" is represented by the chart D located fourth from the left end.

[0072] (Comparative Example 1)

[0073] In Comparative Example 1, the following piston ring assembly was used.

[0074] [Top Ring E1]

[0075] Materials and surface treatment: Steel + chromium nitride film

[0076] Shape: 2.30mm thick × 1.00mm wide

[0077] Tension: 3.0N

[0078] Outer circumference: barrel shape

[0079] Cross-sectional shape: Rectangle + interior bevel

[0080] Opening gap: 0.25mm

[0081] Opening chamfer: 0.15mm

[0082] Chamfer on the lower outer circumference (axial): 0.15mm

[0083] Chamfer (radial) on the lower outer circumference: 0.15mm

[0084] Opening flow area: 0.113mm 2 [Calculation example: s1×g1×f+C1+C2+C3×2=0.25×0.25×80 / 73+0.15] 2 / 2+0.15 2 / 2+0.15 2 / 2×2=0.113mm 2 ]

[0085] [Second Ring E1]

[0086] Materials and surface treatment: Steel + chemical conversion treatment

[0087] Shape: 2.30mm thick × 1.00mm wide

[0088] Tension: 2.5N

[0089] Outer peripheral surface: conical shape

[0090] Cross-sectional shape: scraper

[0091] Opening gap: 0.40mm

[0092] [Oil ring E1]

[0093] Shape: 2.55mm thick × 2.00mm wide

[0094] Tension: 15N

[0095] Ear angle: 20°

[0096] Track shape: 2.00mm thick × 0.35mm wide

[0097] Track materials and surface treatment: steel + chromium nitride film

[0098] Orbital elastic modulus: 196 GPa (196000 N / mm) 2 )

[0099] outer circumference of the track: barrel shape

[0100] Sliding surface shape: b1=0.15, b2=0.014

[0101] Peripheral follower coefficient: 0.2

[0102] [Calculation example: 3 / 2 × Ft × (d1 - a1)] 2 / (E×h12×a1 3 = 3 / 2 × 15 × (73 - 2.00) 2 / (196000 × 0.35 × 2.00) 3 )≈0.20]

[0103] The opening clearance can be measured by inserting a clearance gauge into the opening clearance with the piston ring assembly inserted into the cylinder bore. The opening chamfer and the lower outer circumference chamfer can be measured based on the contour shape of the chamfered portion. The contour shape can be measured manually or using image processing software. Tension can be measured using a manual or automatic tension measuring machine. The track shape (thickness × width) can be measured using a micrometer. The track elastic modulus can be determined using the inherent value of the material or through tensile testing of metallic materials.

[0104] Also Figure 6 As shown in (a), as described above, the experimental results of Comparative Example 1 (low-rotation high-load oil consumption, mode-condition oil consumption, low-rotation high-load gas leakage, mode-condition friction) are 1.00 on the baseline. Furthermore, the ear angle refers to the angle between the ear portion of the spacer ring of the oil ring and the axial direction of the cylinder bore. This ear portion is the end of the spacer ring that is radially opposite to each track along the cylinder bore.

[0105] (Comparative Example 2)

[0106] In Comparative Example 2, the top ring differs from the structure of the piston ring assembly in Comparative Example 1. The following top ring was used in Comparative Example 2.

[0107] [Top Ring E2]

[0108] Materials and surface treatment: Steel + chromium nitride film

[0109] Shape: 2.30mm thick × 1.00mm wide

[0110] Tension: 3.0N

[0111] Outer circumference: barrel shape

[0112] Cross-sectional shape: Rectangle + interior bevel

[0113] Opening gap: 0.18mm

[0114] Opening chamfer: 0.10mm

[0115] Chamfer on the lower outer circumference (axial): 0.10mm

[0116] Chamfer (radial) on the lower outer circumference: 0.08mm

[0117] Opening flow area: 0.067mm 2

[0118] The experimental results in Comparative Example 2 are as follows: Figure 6 As shown in (b).

[0119] Oil consumption at low rotation and high load: 1.10

[0120] Fuel consumption under standard operating conditions: 0.85

[0121] Low-rotation, high-load gas leakage: 0.65

[0122] Mode condition friction: 1.00

[0123] (Comparative Example 3)

[0124] In Comparative Example 3, the oil ring differs from the piston ring assembly structure of Comparative Example 1. The following oil ring was used in Comparative Example 3.

[0125] [Oil ring E2]

[0126] Shape: 2.20mm thick × 2.00mm wide

[0127] Tension: 15N

[0128] Ear angle: 20°

[0129] Track shape: 1.60mm thick × 0.35mm wide

[0130] Track materials and surface treatment: steel + chromium nitride film

[0131] outer circumference of the track: barrel shape

[0132] Sliding surface shape: b1=0.15, b2=0.014

[0133] Peripheral follower coefficient: 0.4

[0134] The experimental results in Comparative Example 3 are as follows: Figure 6 As shown in (c).

[0135] Oil consumption at low rotation and high load: 0.70

[0136] Fuel consumption under standard operating conditions: 0.85

[0137] Low-rotation, high-load gas leakage: 1.00

[0138] Mode-condition friction: 0.85

[0139] (Example 1)

[0140] In Example 1, the piston ring assembly consists of a top ring E2, a second ring E1, and an oil ring E2.

[0141] The experimental results in Example 1 are as follows: Figure 6 As shown in (d).

[0142] Oil consumption at low rotation and high load: 0.80

[0143] Fuel consumption under standard operating conditions: 0.70

[0144] Low-rotation, high-load gas leakage: 0.65

[0145] Mode-condition friction: 0.85

[0146] In Example 1, the opening flow area of ​​the top ring E2 is 0.1 mm. 2 Below this, and the peripheral following coefficient of oil ring E2 is 0.3 or higher. The flow area through the opening of top ring E2 is 0.1 mm. 2The following measures can reduce blow-by. With an outer circumferential following coefficient of 0.3 or higher, the oil ring E2 effectively follows the inner surface of the cylinder bore. Therefore, excess oil adhering to the inner surface of the cylinder bore due to the top ring E2 is effectively scraped off by the oil ring E2. Thus, in the case of using the piston ring assembly of Example 1, the reduction in oil consumption due to the oil ring E2 exceeds the increase in oil consumption due to the top ring E2. In other words, by using the piston ring assembly of Example 1, blow-by, oil consumption, and friction can be reduced respectively. In particular, the friction of the piston ring assembly of Example 1, including both the top ring E2 and the oil ring E2, can be reduced as much as the friction of the piston ring assembly of Comparative Example 3, which includes the oil ring E2.

[0147] (Example 2)

[0148] In Example 2, the oil ring differs from the piston ring assembly structure in Example 1. The following oil ring was used in Example 2.

[0149] [Oil ring E3]

[0150] Shape: 2.20mm thick × 2.00mm wide

[0151] Tension: 15N

[0152] Ear angle: 20°

[0153] Track shape: 1.60mm thick × 0.35mm wide

[0154] Track materials and surface treatment: steel + chromium nitride film

[0155] outer circumference of the track: conical shape

[0156] Sliding surface shape: t1=5.5°, t2=0.014, t3=0.075°

[0157] Peripheral follower coefficient: 0.4

[0158] The experimental results in Example 2 are as follows: Figure 7 As shown in (a).

[0159] Oil consumption at low rotation and high load: 0.70

[0160] Fuel consumption under standard operating conditions: 0.60

[0161] Low-rotation, high-load gas leakage: 0.65

[0162] Model condition friction: 0.70

[0163] In Example 2, the outer peripheral surface of the oil ring has a conical shape, thereby reducing oil consumption and friction compared to Example 1.

[0164] (Example 3)

[0165] In Example 3, the oil ring differs from the structure of the piston ring assembly in Example 1. The following oil ring was used in Example 3.

[0166] [Oil ring E4]

[0167] Shape: 2.20mm thick × 2.00mm wide

[0168] Tension: 15N

[0169] Ear angle: 20°

[0170] Track shape: 1.60mm thick × 0.35mm wide

[0171] Track materials and surface treatment: steel + chromium nitride film

[0172] outer circumference of the track: bullet-shaped

[0173] Sliding surface shape: bt1=0.08, bt2=0.011

[0174] Peripheral follower coefficient: 0.4

[0175] The experimental results in Example 3 are as follows: Figure 7 As shown in (b).

[0176] Oil consumption at low rotation and high load: 0.60

[0177] Fuel consumption under standard operating conditions: 0.65

[0178] Low-rotation, high-load gas leakage: 0.65

[0179] Mode-condition friction: 0.75

[0180] In Example 3, the outer peripheral surface of the oil ring has a bullet-shaped surface, thereby reducing oil consumption and friction compared to Example 1.

[0181] (Comparative Example 4)

[0182] In Comparative Example 4, a piston ring assembly having a top ring E1, a second ring E2 as shown below, and an oil ring E1 was used.

[0183] [Second Ring E2]

[0184] Materials and surface treatment: Steel + chemical conversion treatment

[0185] Shape: 2.30mm thick × 1.00mm wide

[0186] Tension: 2.5N

[0187] Outer peripheral surface: conical shape

[0188] Cross-sectional shape: scraper

[0189] Opening gap: 0.25mm

[0190] The experimental results in Comparative Example 4 are as follows: Figure 8 As shown in (a).

[0191] Oil consumption at low rotation and high load: 1.25

[0192] Fuel consumption under standard operating conditions: 0.80

[0193] Low-rotation, high-load gas leakage: 1.15

[0194] Mode conditional friction: 1.10

[0195] (Example 4)

[0196] In Example 4, the piston ring assembly uses a top ring E2, a second ring E2, and an oil ring E2.

[0197] The experimental results in Example 4 are as follows: Figure 8 As shown in (b).

[0198] Oil consumption at low rotation and high load: 0.80

[0199] Fuel consumption under standard operating conditions: 0.50

[0200] Low-rotation, high-load gas leakage: 0.65

[0201] Model condition friction: 0.82

[0202] (Example 5)

[0203] In Example 5, the oil ring differs from the piston ring assembly structure in Example 4. In Example 5, oil ring E3 is used.

[0204] The experimental results in Example 5 are as follows: Figure 8 As shown in (c).

[0205] Oil consumption at low rotation and high load: 0.70

[0206] Fuel consumption under standard operating conditions: 0.40

[0207] Low-rotation, high-load gas leakage: 0.65

[0208] Mode-condition friction: 0.67

[0209] (Example 6)

[0210] In Example 6, the oil ring differs from the piston ring assembly structure of Example 4. In Example 6, an oil ring E4 is used.

[0211] The experimental results in Example 6 are as follows: Figure 8 As shown in (d).

[0212] Oil consumption at low rotation and high load: 0.60

[0213] Fuel consumption under standard operating conditions: 0.45

[0214] Low-rotation, high-load gas leakage: 0.65

[0215] Model condition friction: 0.72

[0216] Compared to Comparative Example 1, Comparative Example 4 showed increased oil consumption at low rotation and high load, increased gas leakage at low rotation and high load, and increased friction under specific conditions. The piston ring assembly of Comparative Example 4 consisted of rings with diameters greater than 0.1 mm. 2 The opening flow area (0.113mm) 2 The top ring E1 and the second ring E2, which has an opening gap of less than 0.4 mm (0.25 mm), constitute a structure, so the S1 ratio is less than 1.8 (s2 / s1=1.0). Therefore, it is speculated that the reason why the experimental results of Comparative Example 4 are worse than those of Comparative Example 1 is that, under low rotation and high load conditions, the pressure of the second groove ridge increases due to the blow-by gas G, causing the top ring E1 to flutter.

[0217] Each piston ring assembly in Examples 4-6 consists of a ring with a diameter of 0.1 mm. 2 Small opening flow area (0.069mm) 2 The test ring consists of a top ring E2 and a second ring E2 with an opening gap smaller than 0.4 mm (0.25 mm). In Examples 4-6, even when the S1 ratio was less than 1.8 (s2 / s1≈1.39), the amount of blow-by, oil consumption, and friction were reduced compared to Comparative Example 4 or Comparative Example 1. It is speculated that the reason why the experimental results of Examples 4-6 were improved compared to the experimental results of Comparative Example 4 or Comparative Example 1 is that the combination of the top ring E2 and the second ring E2 had a synergistic effect in suppressing the flutter of the top ring E2.

[0218] (Comparative Example 5)

[0219] In Comparative Example 5, the oil ring differs from the structure of the piston ring assembly in Comparative Example 1. The following oil ring was used in Comparative Example 5.

[0220] [Oil Ring E5]

[0221] Shape: 2.20mm thick × 2.00mm wide

[0222] Tension: 20N

[0223] Ear angle: 20°

[0224] Track shape: 1.60mm thick × 0.35mm wide

[0225] Track materials and surface treatment: steel + chromium nitride film

[0226] outer circumference of the track: barrel shape

[0227] Sliding surface shape: b1=0.15, b2=0.014

[0228] Peripheral follower coefficient: 0.54

[0229] The experimental results in Comparative Example 5 are as follows: Figure 9 As shown in (a).

[0230] Oil consumption at low rotation and high load: 0.55

[0231] Fuel consumption under standard operating conditions: 0.70

[0232] Low-rotation, high-load gas leakage: 1.00

[0233] Mode condition friction: 0.95

[0234] (Comparative Example 6)

[0235] In Comparative Example 6, the oil ring differs from the piston ring assembly structure of Comparative Example 1. The following oil ring was used in Comparative Example 6.

[0236] [Oil ring E6]

[0237] Shape: 2.20mm thick × 2.00mm wide

[0238] Tension: 12N

[0239] Ear angle: 20°

[0240] Track shape: 1.35mm thick × 0.35mm wide

[0241] Track materials and surface treatment: steel + chromium nitride film

[0242] outer circumference of the track: barrel shape

[0243] Sliding surface shape: b1=0.15, b2=0.014

[0244] Peripheral follower coefficient: 0.54

[0245] The experimental results in Comparative Example 6 are as follows: Figure 9 As shown in (b).

[0246] Oil consumption at low rotation and high load: 0.60

[0247] Fuel consumption under standard operating conditions: 0.75

[0248] Low-rotation, high-load gas leakage: 1.00

[0249] Model condition friction: 0.70

[0250] (Example 7)

[0251] In Example 7, the piston ring assembly uses a top ring E2, a second ring E1, and an oil ring E5.

[0252] The experimental results in Example 7 are as follows: Figure 9 As shown in (c).

[0253] Oil consumption at low rotation and high load: 0.65

[0254] Fuel consumption under standard operating conditions: 0.55

[0255] Low-rotation, high-load gas leakage: 0.65

[0256] Mode condition friction: 0.95

[0257] (Example 8)

[0258] In Example 8, the piston ring assembly uses a top ring E2, a second ring E1, and an oil ring E6.

[0259] The experimental results in Example 8 are as follows: Figure 9 As shown in (d).

[0260] Oil consumption at low rotation and high load: 0.70

[0261] Fuel consumption under standard operating conditions: 0.60

[0262] Low-rotation, high-load gas leakage: 0.65

[0263] Model condition friction: 0.70

[0264] (Example 9)

[0265] exist Figure 9 In Example 9 shown in (e), a top ring E2, a second ring E2, and an oil ring E5 are used as the piston ring assembly.

[0266] The experimental results in Example 9 are shown below.

[0267] Oil consumption at low rotation and high load: 0.65

[0268] Fuel consumption under standard operating conditions: 0.35

[0269] Low-rotation, high-load gas leakage: 0.65

[0270] Model condition friction: 0.92

[0271] (Example 10)

[0272] In Example 10, the piston ring assembly uses a top ring E2, a second ring E2, and an oil ring E6.

[0273] The experimental results in Example 10 are as follows: Figure 9 As shown in (f).

[0274] Oil consumption at low rotation and high load: 0.70

[0275] Fuel consumption under standard operating conditions: 0.40

[0276] Low-rotation, high-load gas leakage: 0.65

[0277] Mode-condition friction: 0.67

[0278] In Example 7, by using an oil ring E5 with a tension of 20 N and a peripheral follower coefficient of 0.54, oil consumption was reduced compared to Example 1. In Example 9, by using an oil ring E5, oil consumption was reduced compared to Example 4. In Example 8, by using an oil ring E6 with a tension of 12 N and a peripheral follower coefficient of 0.54, oil consumption and friction were reduced compared to Example 1. In Example 10, by using an oil ring E6, oil consumption and friction were reduced compared to Example 4.

[0279] Label Explanation

[0280] 1…Piston ring assembly; 2…Piston; 2a…Outer surface; 11d, 21d, 31d…Outer peripheral surface; 3…Cylinder bore; 3a…Inner surface; 10…Top ring; 11, 21…Main body; 11a…Side side (first side); 11b…Side side (second side); 11c, 21c, 31c…Inner peripheral surface; 11e…Beveled surface of lower outer peripheral surface; 13…Opening end (first opening end); 13a…Beveled surface of opening (first opening beveled surface); 14…Opening end (Second opening end); 14a… Opening chamfered surface (second opening chamfered surface); 15… Opening portion; 16… Opening chamfered portion (first opening chamfered portion); 17… Opening chamfered portion (second opening chamfered portion); 18, 18a, 18b… Outer peripheral lower surface chamfered portion; 20… Second ring; 23… Opening end (third opening end); 24… Opening end (fourth opening end); 25… Opening portion; 30… Oil ring; 31… Track; D1… Axial; D2… Radial.

Claims

1. A piston ring assembly comprising a top ring and an oil ring, which is inserted into the cylinder bore of an internal combustion engine when mounted on a piston, wherein... The top ring has an annular main body portion, which includes an inner circumferential surface, an outer circumferential surface, a first side surface and a second side surface that are substantially orthogonal to the inner circumferential surface, and a first opening end portion and a second opening end portion that are opposite to each other to form an opening portion. The oil ring has a pair of tracks that are opposite each other. The opening flow area of ​​the top ring is 0.1 mm. 2 the following, The peripheral following coefficient of the oil ring is greater than 0.

3. The main body is provided with a first opening chamfered surface, a second opening chamfered surface, and an outer peripheral lower surface chamfered surface. The first opening chamfered surface is located between the end of the first opening and the outer peripheral surface. The second opening chamfered surface is located between the end of the second opening and the outer peripheral surface. The outer peripheral lower surface chamfered surface is located between one of the first side surface and the second side surface and the outer peripheral surface. When the top ring and the oil ring are inserted into the cylinder bore while the piston is installed, A first chamfered opening is formed between the inner surface of the cylinder bore and the first chamfered opening surface; a second chamfered opening is formed between the inner surface and the second chamfered opening surface; and an outer lower surface chamfer is formed between the inner surface and the outer lower surface chamfer. With the gap between the first opening end and the second opening end set as s1, the gap between the outer surface of the piston and the inner surface of the cylinder bore set as g1, the correction coefficient based on the inner diameter of the cylinder bore set as f, the size of the chamfered portion of the first opening set as C1, the size of the chamfered portion of the second opening set as C2, and the size of the chamfered portion of the lower outer circumference set as C3, the flow area of ​​the opening is expressed as s1×g1×f+C1+C2+2×C3. With the tension of the oil ring set to Ft, the inner diameter of the cylinder bore set to d1, the thickness of each of the pair of tracks along the radial direction of the cylinder bore set to a1, the elastic modulus of the material constituting each pair of tracks set to E, and the width of each of the pair of tracks along the axial direction of the cylinder bore set to h12, the peripheral following coefficient is expressed as 3 / 2 × Ft × (d1 - a1). 2 / (E×h12×a13).

2. The piston ring assembly according to claim 1, wherein, The peripheral following coefficient of the oil ring is below 0.

8.

3. The piston ring assembly according to claim 1, wherein, The radial dimension of the chamfered portion of the outer peripheral lower surface is smaller than the axial dimension of the chamfered portion of the outer peripheral lower surface.

4. The piston ring assembly according to any one of claims 1 to 3, wherein, The piston ring assembly also includes a second ring. The second ring has an annular second main body portion, which includes a third opening end and a fourth opening end that are opposite each other to form a second opening. The ratio of the gap between the third opening end and the fourth opening end to the gap between the first opening end and the second opening end is 1.8 or less.

5. A piston ring assembly comprising a top ring and an oil ring, which is inserted into the cylinder bore of an internal combustion engine when mounted on a piston, wherein... The top ring has an annular main body portion, which includes an inner circumferential surface, an outer circumferential surface, a first side surface and a second side surface that are substantially orthogonal to the inner circumferential surface, and a first opening end portion and a second opening end portion that are opposite to each other to form an opening portion. The oil ring has a pair of tracks that are opposite each other. The opening flow area of ​​the top ring is 0.1 mm. 2 the following, The peripheral following coefficient of the oil ring is greater than 0.

3. The piston ring assembly also includes a second ring. The second ring has an annular second main body portion, which includes a third opening end and a fourth opening end that are opposite each other to form a second opening. The ratio of the gap between the third opening end and the fourth opening end to the gap between the first opening end and the second opening end is 1.8 or less.

6. The piston ring assembly according to any one of claims 1 to 3 and 5, wherein, The outer peripheral surfaces of the pair of tracks each have either a conical shape or a bullet shape.

Images