Piston ring of internal combustion engine

Abstract

To provide a piston ring of an internal combustion engine suppressing blow-by gas from passing through an abutment part.SOLUTION: A piston ring of an internal combustion engine includes a protruding part 2 provided so as to protrude in a circumferential direction C of the piston ring 1, and a recessed part 3 formed to the other edge surface 10B along the circumferential direction C and formed so as to store the protruding part 2, on one edge surface 10A of a pair of edge surfaces of an abutment part 10 of the piston ring 1. The piston ring includes: a protruding-side facing surface 4 provided to the protruding part 2; and a reinforcement part 6 provided on at least one facing surface of the recessed part-side facing surface 5 provided to the recessed part 3, extending over the whole facing surface in a width direction along the diameter direction R of the piston ring 1, and provided so as to protrude from the facing surface.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to piston rings for internal combustion engines. [Background technology]

[0002] Patent Document 1 discloses a configuration in which opposing end faces of a butt portion of a piston ring of an internal combustion engine are formed into an uneven shape with steps in the vertical direction, and the convex portion of one end face is housed in the concave portion of the other end face. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 07-332496 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional joint structure disclosed in Patent Document 1 and the like, the uneven gap forms a path for blow-by gas passing through the circumferential direction of the piston ring, and this path can allow blow-by gas to escape into the crank chamber.

[0005] An object of the present disclosure is to provide a piston ring for an internal combustion engine that can suppress the escape of blow-by gas through a butt portion. [Means for solving the problem]

[0006] A piston ring for an internal combustion engine according to one aspect of an embodiment of the present invention comprises: a convex portion provided on one of a pair of opposing end faces of a butt portion of the piston ring, protruding from the end face in a circumferential direction of the piston ring; a recess formed on the other of the pair of end faces, recessed from the end face along the circumferential direction of the piston ring, so as to be able to accommodate the convex portion; a convex-side opposing surface provided on the convex portion, which faces the recess when the convex portion is accommodated in the recess; a recess-side opposing surface provided on the recess, which faces the convex-side opposing surface when the convex portion is accommodated in the recess; and a streak portion provided on at least one of the convex-side opposing surface and the recess-side opposing surface, which extends across the entire width direction of the opposing surface along the radial direction of the piston ring and protrudes from the opposing surface. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a piston ring for an internal combustion engine that can suppress the escape of blow-by gas through a butt portion. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an enlarged perspective view of the vicinity of a gap portion of a piston ring according to an embodiment before the piston ring is mounted in a cylinder; [Figure 2] FIG. 1 is an enlarged perspective view of the vicinity of a gap portion of a piston ring according to an embodiment after the piston ring is mounted in a cylinder; [Figure 3] FIG. 10 is a perspective view showing a modified example of the joint portion; [Figure 4] Schematic diagram showing modified cross-sectional shapes of muscle parts [Figure 5] FIG. 10 is a diagram showing an example of the arrangement of the ribs when the ribs are provided on both the convex portion-facing surface and the concave portion-facing surface. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions will be omitted.

[0010] The piston ring 1 according to the embodiment is a component fitted to the circumferential surface of a piston disposed in a cylinder of an internal combustion engine. By installing the piston ring 1 on the piston, it is possible to prevent gas in the combustion chamber of the internal combustion engine from blowing out into the crankcase from between the piston and the cylinder wall. Combustion gas leaking into the crankcase from gaps between the piston and the cylinder wall of such an internal combustion engine is called blow-by gas.

[0011] Fig. 1 is an enlarged perspective view of the vicinity of a butt joint 10 of a piston ring 1 according to an embodiment before it is mounted in a cylinder. The piston ring 1 is an annular member, and is cut at one location in the circumferential direction of the annular shape. This cut portion is the butt joint 10, and when mounted on a piston, the piston ring 1 is elastically deformed to widen the gap at the butt joint 10 before being assembled to the piston. Fig. 1(A) shows the state in which the gap at the butt joint 10 has been widened in this manner.

[0012] The abutment 10 shown in Fig. 1 is a double-wrap type abutment. The double-wrap type abutment is configured such that one end face 10A of the abutment 10 has a convex portion 2 with a triangular cross section extending circumferentially, and the other end face 10B has a concave portion 3 that engages with the convex portion 2, and the convex portion 2 and the concave portion 3 are overlapping when viewed from the sliding direction S of the piston.

[0013] The protrusion 2 is provided on one end face 10A of a pair of opposing end faces of the butt joint 10 of the piston ring 1, protruding from this end face 10A in the circumferential direction of the piston ring 1. The recess 3 is formed on the other end face 10B of the pair of opposing end faces of the butt joint 10 of the piston ring 1, recessed from the end face 10B along the circumferential direction C of the piston ring 1, and is formed to be able to accommodate the protrusion 2.

[0014] The protrusion 2 is provided with a protrusion-side opposing surface 4 that is disposed opposite the recess 3 when the protrusion 2 is accommodated in the recess 3. The protrusion-side opposing surface 4 corresponds to the hypotenuse of the right-angled triangle of the cross-sectional shape of the protrusion 2. The other two sides of the right-angled triangle of the cross-sectional shape of the protrusion 2 correspond to the outer peripheral surface 11 of the piston ring 1 in the radial direction R and one side surface 12 of a pair of side surfaces in the sliding direction S.

[0015] The recess 3 is provided with a recess-side opposing surface 5 that is disposed opposite to the protrusion-side opposing surface 4 when the protrusion 2 is housed in the recess 3.

[0016] In particular, in this embodiment, a plurality of streaks 6 are provided on the recess-side opposing surface 5. In Fig. 1(A), the portions where the streaks 6 are provided are indicated by hatching. In Fig. 1(B), the recess-side opposing surface 5 and the streaks 6 provided on the recess-side opposing surface 5 are shown in an enlarged view. As shown in Fig. 1(B), the streaks 6 extend across the entire width direction of the recess-side opposing surface 5 along the radial direction R of the piston ring 1, and are provided so as to protrude from the recess-side opposing surface 5.

[0017] Furthermore, a plurality of streaks 6 are provided on the recess-side opposing surface 5 along the circumferential direction C of the piston ring 1. The plurality of streaks 6 are arranged so that their extending directions are parallel to each other, and each streak 6 is formed so as to extend in a direction perpendicular to the circumferential direction C of the piston ring 1. The streaks 6 have, for example, a triangular cross-sectional shape when viewed from the extending direction, with the base of the triangle being in surface contact with the recess-side opposing surface 5 and the apex of the triangle being located at a position farthest from the recess-side opposing surface 5. The streaks 6 are preferably made of resin.

[0018] Fig. 2 is an enlarged perspective view of the vicinity of the butt ends 10 of the piston ring 1 according to the embodiment after it has been installed in a cylinder. The piston ring 1 is assembled into the ring groove of the piston with the gap between the butt ends 10 widened by elastic deformation, and then elastically returns to its original length so that the gap between the butt ends 10 is fitted to the piston. When the piston is further inserted into the cylinder, the outer peripheral surface 11 is pressed radially inward by the cylinder wall, further narrowing the gap between the butt ends 10. Fig. 2(A) shows the installed state in which the gap between the butt ends 10 has been narrowed in this way.

[0019] FIG. 2(B) is a schematic diagram showing the process in which the gap between the butt ends 10 is narrowed. As shown by arrow A in FIG. 2(B), the convex portion 2 approaches the concave portion 3 in the circumferential direction C. At this time, the piston ring 1 is fitted into the ring groove of the piston, so its movement in the sliding direction S (the vertical direction in the figure) is restricted. Furthermore, a piston assembly jig (for example, a ring whose inner diameter gradually decreases until it becomes the bore diameter at the outlet) is passed through the piston, and the piston ring 1 is narrowed to the bore diameter, and then the piston is inserted into the cylinder block. In this way, in the process in which the diameter of the piston ring 1 is narrowed, the butt ends 10 are narrowed without any relief in the sliding direction S.

[0020] Furthermore, as shown in Figure 2(B), when the gap between the joints 10 is narrowed, the rib portion 6 provided on the recessed portion side opposing surface 5 has a height greater than the gap between the recessed portion side opposing surface 5 and the convex portion side opposing surface 4 when the convex portion 2 is accommodated in the recessed portion 3, and is formed so that the tip portion 61 comes into contact with the convex portion side opposing surface 4.

[0021] 2(C) is a schematic diagram showing the state after the gap between the gaps 10 has been narrowed. Because the streaks 6 are formed as described above, after the convex portions 2 have finally moved to a position where the recess-side opposing surface 5 and the convex-side opposing surface 4 are arranged opposite each other as shown in FIG. 2(C), the tips 61 of the streaks 6 will be located geometrically closer to the interior of the convex portions 2 than the convex-side opposing surface 4. Here, because the streaks 6 are made of resin as described above, in the state shown in FIG. 2(C), the tips 61 of the streaks 6 are actually pressed toward the recess-side opposing surface 5 by the convex-side opposing surface 4 and are crushed. As a result, the gap between the recess-side opposing surface 5 and the convex-side opposing surface 4 is more reliably sealed by the streaks 6.

[0022] Here, in the double-wrap type abutment, the gap between the convex portion 2 and the concave portion 3 opens to the bottom surface of the piston ring 1, i.e., the side surface 12 shown in Figures 1 and 2, which is located on the crankcase side of the internal combustion engine. Since the piston ring 1 fits into the groove of the piston, the opening on the side surface 12 is closed by the wall surface of the groove, and this also closes the flow path of the blow-by gas G.

[0023] However, in the conventional double-wrap type, although it is very narrow, a flow path remains for blow-by gas G to pass through the inclined surface portion of the joint in the circumferential direction C. That is, in a configuration in which the streak portion 6 according to this embodiment is not provided, as in the conventional double-wrap type joint, as shown by the dotted arrow in Fig. 2(A) , blow-by gas G may pass through the gap between end faces 10A and 10B, through the gap between the recess-side opposing surface 5 and the protrusion-side opposing surface 4 in the circumferential direction C, and flow toward the crank chamber through the gap between the tip of protrusion 2 and the base end of recess 3.

[0024] In contrast to this, in this embodiment, the rib portions 6 provided on the recess-side opposing surface 5 seal the gap between the recess-side opposing surface 5 and the convex-side opposing surface 4 over the entire width direction of the opposing surfaces, so that the flow of blow-by gas G is blocked at the positions of the rib portions 6, as shown in Fig. 2(C) . As a result, the piston ring 1 of this embodiment can block the flow path of blow-by gas G in the gap between the recess-side opposing surface 5 and the convex-side opposing surface 4 with the rib portions 6, so that it is possible to suppress the escape of blow-by gas G through the abutment portion 10 and significantly reduce the amount of blow-by gas.

[0025] As a method for closing the gap between the recess-side facing surface 5 and the protrusion-side facing surface 4, a configuration in which resin is applied to the entire recess-side facing surface 5 or the entire protrusion-side facing surface 4 in a single layer, as in the present embodiment, is also possible. However, a configuration in which stripes of streaks 6 are provided, as in the present embodiment, is more advantageous than a configuration in which resin is uniformly applied to the facing surfaces. In the configuration of the present embodiment, multiple streaks 6 are arranged on the same facing surface at intervals in the circumferential direction C, creating gaps on both sides of each streak 6 in the circumferential direction C. When the gap between the joints 10 is narrowed, the tip ends 61 of the streaks 6 are in contact with another facing surface, and therefore the streaks 6 are subjected to an external force from the other facing surface through the tip ends 61 in the direction opposite to the movement direction of the facing surface on which the streaks 6 are installed. In this case, in the present embodiment, the gaps on both sides of the multiple streaks 6 in the circumferential direction C provide ample room for the tip ends 61 of the streaks 6 to deform along the movement direction. This makes it easier for the rib portion 6 to deform along the opposing surfaces as the gap at the joint portion 10 narrows, thereby more reliably closing the gap between the recess side opposing surface 5 and the protrusion side opposing surface 4.

[0026] It is preferable that the width dimension of the streak portions 6 in the direction perpendicular to the extending direction (the dimension along the circumferential direction C in the examples of Figs. 1 and 2) is as small as possible. This allows the streak portions 6 to deform more smoothly as the gap between the gaps 10 is narrowed, and makes it possible to more reliably close the gap between the recess-side opposing surface 5 and the protrusion-side opposing surface 4.

[0027] 1 and 2 show an example of a configuration in which the streaks 6 are provided on the recess-side facing surface 5, but the streaks 6 may be provided on the convex-side facing surface 4, or may be provided on both the recess-side facing surface 5 and the convex-side facing surface 4. In short, it is sufficient that the streaks 6 are provided on at least one of the convex-side facing surface 4 and the recess-side facing surface 5.

[0028] 1 and 2 show an example of a configuration in which two rib portions 6 are provided, but the number of rib portions 6 may be one or more, i.e., three or more. However, it is preferable to provide a plurality of rib portions 6 along the circumferential direction C. This makes it possible to more reliably suppress the flow of blow-by gas G along the circumferential direction C in the gap between the convex portion-side opposing surface 4 and the concave portion-side opposing surface 5.

[0029] 1 and 2 show an example in which the streak portions 6 extend in a direction perpendicular to the circumferential direction C, but the streak portions 6 may extend at least across the entire width of the opposing surface, and may extend in a direction inclined relative to the perpendicular direction. Alternatively, the streak portions 6 may be curved rather than linear.

[0030] 1 and 2 show an example in which the ridge portions 6 are made of resin, but they may be made of a material at least lower in hardness than the opposing surface of the piston ring 1, and may be made of a material other than resin, such as a soft metal such as aluminum or magnesium, or a composite material such as FRP. This allows the tip portions 61 of the ridge portions 6 to be crushed by the opposing surface when the piston is attached to the piston, thereby improving the sealing performance of the gap between the convex-side opposing surface 4 and the concave-side opposing surface 5 by the ridge portions 6 and more reliably preventing blow-by gas G from escaping through the abutment 10.

[0031] For example, when a resin material is used, the streak portions 6 can be formed by applying the resin material to the opposing surface. Alternatively, the streak portions 6 may be formed in advance and then adhered to the opposing surface using an adhesive or the like. Although FIGS. 1 and 2 illustrate a configuration in which multiple streak portions 6 are individually installed on one opposing surface, multiple streak portions 6 may also be integrally formed. In this configuration, for example, a single member is formed having a bottom plate portion with an area approximately the same as the opposing surface and multiple streak portions protruding from the bottom plate portion, and the bottom plate portion is adhered to the opposing surface, thereby forming multiple streak portions 6 on the opposing surface.

[0032] 1 and 2 show an example in which the ridges 6 are separate from the piston ring 1, and are made of resin while the piston ring 1 is made of metal, but the ridges 6 may be formed integrally with the piston ring 1. In this configuration, for example, the entire piston ring can be made of resin and formed by injection molding. In addition, in this configuration, the side opposite to the above-mentioned one side 12 of the pair of side surfaces in the sliding direction of the piston ring, i.e., the side surface on the combustion chamber side, is exposed to combustion gas, so it is preferable to form a plating coating of Cu, Ni, or the like on this side surface and combine it with a coating with good thermal conductivity such as DLC to protect the resin portion of the ring body from heat damage.

[0033] Fig. 3 is a perspective view showing a modified example of the butt joint. In the example of Figs. 1 and 2, the piston ring 1 having the double-wrap type butt joint 10 is illustrated, but the streak portion 6 according to this embodiment can also be applied to other types of butt joints. In short, it is sufficient if the butt joint has elements corresponding to the convex portion 2, the concave portion 3, the convex portion-side opposing surface 4, and the concave portion-side opposing surface 5 in the example of Figs. 1 and 2.

[0034] FIG. 3(A) shows an enlarged view of the vicinity of the butt joint 20 of a piston ring 1A according to a first modified example. The butt joint 20 shown in FIG. 3(A) is a step-type butt joint. The step-type butt joint is configured such that a convex portion 2A extending in the circumferential direction is provided on one end face 20A of the butt joint 20, and a concave portion 3A engaging with the convex portion 2A is provided on the other end face 20B, and the convex portion 2A and the concave portion 3A are superimposed when viewed from the sliding direction S of the piston. The convex portion 2A and the concave portion 3A are provided over the entire width of the piston ring 1 along the radial direction R, that is, over the entire range between the outer peripheral surface 11A and the inner peripheral surface 13A of the piston ring 1A. The cross-sectional shape of the convex portion 2A is, for example, rectangular.

[0035] The protrusion 2A is provided with a protrusion-side opposing surface 4A that is disposed opposite the recess 3A when the protrusion 2A is accommodated in the recess 3A. The protrusion-side opposing surface 4A corresponds to the long side of the rectangular cross-sectional shape of the protrusion 2A. The recess 3A is provided with a recess-side opposing surface 5A that is disposed opposite the protrusion-side opposing surface 4A when the protrusion 2A is accommodated in the recess 3A. The protrusion-side opposing surface 4A and the recess-side opposing surface 5A are preferably disposed parallel to a pair of side surfaces 14A in the sliding direction S of the piston ring 1A.

[0036] In the first modified example, a plurality of streaks 6 are provided on the convex-side opposing surface 4A. In Fig. 3(A), the portions where the streaks 6 are provided are indicated by hatching. As in the above embodiment, the streaks 6 extend across the entire width direction (radial direction R) of the convex-side opposing surface 4A.

[0037] In the piston ring 1A of the first variant, the rib portion 6 provided on the convex side opposing surface 4A seals the gap between the convex side opposing surface 4A and the concave side opposing surface 5A over the entire width direction of the opposing surfaces, making it possible to stop the flow of blow-by gas G at the position of the rib portion 6 and more reliably preventing the blow-by gas G from escaping through the joint portion 20.

[0038] The streak portion 6 may be provided on at least one of the convex portion-side opposing surface 4A and the recessed portion-side opposing surface 5A, and may be provided on the recessed portion-side opposing surface 5A, or may be provided on both the convex portion-side opposing surface 4A and the recessed portion-side opposing surface 5A. At least one streak portion 6 may be provided on the convex portion-side opposing surface 4A or the recessed portion-side opposing surface 5A, but it is preferable that a plurality of streak portions 6 are provided along the circumferential direction C.

[0039] FIG. 3(B) shows an enlarged view of the vicinity of a gap 30 of a piston ring 1B according to a second modification. The gap 30 shown in FIG. 3(B) is a type of step-type gap. The gap shown in FIG. 3(B) is configured such that a circumferentially extending convex portion 2B is provided on one end face 30A of the gap 30, and a concave portion 3B that engages with the convex portion 2B is provided on the other end face 30B, and the convex portion 2B and the concave portion 3B are superimposed when viewed from the sliding direction S of the piston. In this gap, the convex portion 2B and the concave portion 3B are provided on a part of the outer peripheral surface 11B side in the width direction along the radial direction R of the piston ring 1. The cross-sectional shape of the convex portion 2B is, for example, rectangular with a longer side dimension shorter than that of the step-type convex portion 2A shown in FIG. 3(A).

[0040] The protrusion 2B is provided with a first convex-side opposing surface 4B that is disposed opposite the recess 3B when the protrusion 2B is accommodated in the recess 3B. The first convex-side opposing surface 4B corresponds to the long side of the rectangular cross-sectional shape of the protrusion 2B. The recess 3B is provided with a first recess-side opposing surface 5B that is disposed opposite the first convex-side opposing surface 4B when the protrusion 2B is accommodated in the recess 3B. The first convex-side opposing surface 4B and the first recess-side opposing surface 5B are preferably disposed parallel to a pair of side surfaces 14B in the sliding direction S of the piston ring 1B.

[0041] Furthermore, the protrusion 2B is provided with a convex-side second opposing surface 7 that is disposed opposite the recess 3B when the protrusion 2B is accommodated in the recess 3B. The convex-side second opposing surface 7 corresponds to the shorter side of the rectangular cross-sectional shape of the protrusion 2B. The recess 3B is provided with a recess-side second opposing surface 8 that is disposed opposite the convex-side second opposing surface 7 when the protrusion 2B is accommodated in the recess 3B. The convex-side second opposing surface 7 and the recess-side second opposing surface 8 are preferably disposed parallel to the outer peripheral surface 11B of the piston ring 1B.

[0042] In the second modified example, a plurality of streaks 6 are provided on the convex-side first opposing surface 4B. As in the above embodiment, the streaks 6 extend over the entire width direction (radial direction R) of the convex-side first opposing surface 4B. In addition, in the second modified example, a plurality of streaks 6 are also provided on the recess-side second opposing surface 8. The streaks 6 extend over the entire width direction (sliding direction S) of the recess-side second opposing surface 8. In FIG. 3(B), the portions where the streaks 6 are provided are indicated by hatching.

[0043] In the piston ring 1B of the second modification, the rib portions 6 provided on the convex-side first opposing surface 4B seal the gap between the convex-side first opposing surface 4B and the recess-side first opposing surface 5B over the entire width direction of the opposing surfaces. Furthermore, the rib portions 6 provided on the recess-side second opposing surface 8 seal the gap between the convex-side second opposing surface 7 and the recess-side second opposing surface 8 over the entire width direction of the opposing surfaces. As a result, the piston ring 1B of the second modification can also stop the flow of blow-by gas G at the positions of the rib portions 6, and can more reliably prevent the blow-by gas G from escaping through the butt portion 30.

[0044] The streaks 6 may be provided on at least one of the convex-side first opposing surface 4B and the concave-side first opposing surface 5B, and may be provided on the concave-side first opposing surface 5B, or may be provided on both the convex-side first opposing surface 4B and the concave-side first opposing surface 5B. Similarly, the streaks 6 may be provided on at least one of the convex-side second opposing surface 7 and the concave-side second opposing surface 8, and may be provided on the convex-side second opposing surface 7, or may be provided on both the convex-side second opposing surface 7 and the concave-side second opposing surface 8. At least one streak 6 may be provided on the convex-side first opposing surface 4B, the concave-side first opposing surface 5B, the convex-side second opposing surface 7, or the concave-side second opposing surface 8, and preferably a plurality of streaks 6 are provided along the circumferential direction C.

[0045] Fig. 4 is a schematic diagram showing modified cross-sectional shapes of the streak portions. In the examples of Fig. 1 and Fig. 2, as shown in Fig. 4(A), the cross-sectional shape of the streak portions 6 when viewed from the extending direction is triangular, but the cross-sectional shape of the streak portions 6 may be other than triangular. The cross-sectional shape of the streak portions 6 may be formed so that the height is greater than the distance between the recess-side opposing surface 5 and the protrusion-side opposing surface 4 when the protrusion 2 is accommodated in the recess 3, and the tip end farthest from one of the protrusion-side opposing surfaces 4 and the recess-side opposing surface 5 on which the streak portions 6 are installed comes into contact with the other opposing surface.

[0046] For example, like the streak portion 6A shown in FIG. 4(B), it may have a cross-sectional shape having a pair of concave oblique sides 61A, 62A recessed toward the center and a vertex 63A where the ends of the pair of oblique sides 61A, 62A overlap.

[0047] Also, it may have a semicircular cross section like the streak portion 6B shown in FIG. 4(C), or a rectangular cross section like that shown in FIG. 4(D).

[0048] Fig. 5 is a diagram showing an example of the arrangement of streaks when streaks are provided on both the convex-side opposing surface 4 and the recess-side opposing surface 5. When a plurality of streaks 6D are provided on the recess-side opposing surface 5 and a plurality of streaks 6E are provided on the convex-side opposing surface 4 as shown in Fig. 5, it is preferable that the extension direction of the streaks 6E provided on the convex-side opposing surface 4 and the extension direction of the streaks 6D provided on the recess-side opposing surface 5 are inclined in opposite directions from a direction perpendicular to the circumferential direction C (for example, the radial direction R).

[0049] 2(B) and 2(C), when the piston ring 1 is assembled to the piston and the piston is inserted into the cylinder, the gap between the abutment portions 10 is narrowed along the circumferential direction C. At this time, by making the extending directions of the streaks 6D provided on the recess-side opposing surface 5 and the streaks 6E provided on the convex-side opposing surface 4 different as in the example of FIG. 5, the contact area between the streaks 6D and 6E can be reduced when the streaks 6D and 6E come into contact while moving in opposite directions. This makes it possible to prevent the streaks 6D and 6E from peeling off due to an external force received from the opposing surfaces on which they are provided at the time of contact, and makes it easier to maintain the effect of suppressing the blow-by gas G.

[0050] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples made by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements of the above-described specific examples, as well as their arrangement, conditions, shape, etc., are not limited to those exemplified and can be modified as appropriate. The elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise. [Explanation of symbols]

[0051] 1, 1A, 1B Piston rings 2, 2A, 2B convex part 3, 3A, 3B recess 4, 4A Convex side facing surface 5, 5A Concave side facing surface 4B First opposing surface on the convex side 5B Recess side first opposing surface 7 Second opposing surface on the convex side 8 Second opposing surface on the recess side 6, 6A, 6B, 6C, 6D, 6E muscles 10, 20, 30 joint section C circumferential direction R Radial direction

Claims

1. A piston ring for an internal combustion engine, a protrusion provided on one of a pair of opposing end faces of the butt joint of the piston ring so as to protrude from the end face in a circumferential direction of the piston ring; a recess formed in the other of the pair of end faces so as to be recessed from the end face along a circumferential direction of the piston ring and capable of accommodating the protrusion; a convex portion-side opposing surface that is provided on the convex portion and that faces the recessed portion when the convex portion is accommodated in the recessed portion; a recess-side opposing surface that is provided in the recess and that faces the protrusion-side opposing surface when the protrusion is accommodated in the recess; a streak portion provided on at least one of the convex portion-side opposing surface and the concave portion-side opposing surface, extending across the entire width direction of the opposing surface along the radial direction of the piston ring and protruding from the opposing surface; A piston ring for an internal combustion engine.

2. A plurality of the streaks are provided along the circumferential direction.

2. The piston ring for an internal combustion engine according to claim 1.

3. The muscle portion is made of resin.

2. The piston ring for an internal combustion engine according to claim 1.

4. The streak portion is formed to extend in a direction perpendicular to the circumferential direction.

2. The piston ring for an internal combustion engine according to claim 1.

5. The muscle portion is provided on both the convex portion side opposing surface and the concave portion side opposing surface, The extension direction of the streaks provided on the convex portion-side opposing surface and the extension direction of the streaks provided on the concave portion-side opposing surface are formed so as to be inclined in opposite directions from a direction perpendicular to the circumferential direction.

2. The piston ring for an internal combustion engine according to claim 1.

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