JP2020204349A - piston ring - Google Patents

Abstract

To provide a piston ring capable of reducing oil consumption.SOLUTION: An outer peripheral surface 1 of a side rail 11 includes a pair of side surface adjacent portions 3 and 4, an outermost diameter portion 6, and at least one recessed portion 7, 8. In a side rail circumferential direction view, a contour line L6 of the outermost diameter portion is a curve having a curvature center O6, and the curvature center O6 is disposed on the inner side in a diametrical direction than common tangents L1 and L2 of contour lines L3 and L4 of the side surface adjacent portions 3 and 4 and the contour line L6 of the outermost diameter portion 6. Furthermore, in a side rail circumferential direction view, contour lines L7 and L8 of the recessed portions 7 and 8 are curves having curvature centers O7 and O8, and the curvature centers O7 and O8 are disposed on the outer side in the diametrical direction than the common tangents L1 and L2.SELECTED DRAWING: Figure 6

Description

The present invention relates to a piston ring mounted on a piston for an internal combustion engine.

Pistons for internal combustion engines include piston rings such as a compression ring (pressure ring) for sealing combustion gas and oil, and an oil ring (oil control ring) for controlling oil adhering to the inner peripheral surface of the cylinder. It is installed. The piston ring is an annular ring having a joint portion and a sliding surface on the outer periphery.

Some conventional piston rings are side rails of oil rings, which are provided with small-sized protrusions on the outer peripheral surface of the side rails (see, for example, "Patent Document 1"). According to this conventional technique, even if the side rail is worn, the small protrusions do not increase the contact width of the side rail with respect to the cylinder, and the decrease in surface pressure of the side rail with respect to the cylinder can be suppressed. .. Therefore, according to this conventional technique, it is possible to prevent deterioration of the oil scraping performance and, by extension, prevent an increase in oil consumption.

Further, in some other conventional piston rings, a protrusion is provided on the outer surface of the side rail, and the protrusion is shifted to one side in the axial direction from the center (see, for example, "Patent Document 2"). According to this conventional technique, by shifting the protrusion provided on the outer peripheral surface of the side rail to one side in the axial direction, the oil scraping action is enhanced and the oil scraping is suppressed. Therefore, according to this conventional technique, oil consumption can be reduced.

Jikkenhei 4-11959 JP-A-2016-169791

However, all of the above-mentioned prior arts have room for further improvement in reducing oil consumption.

An object of the present invention is to provide a piston ring capable of reducing oil consumption.

The piston ring according to the present invention is a piston ring extending around an axis, and the outer peripheral surface of the piston ring is a pair of side surface adjacent portions adjacent to each of the two side surfaces of the piston ring. , The outermost diameter portion which is arranged between the pair of side surface adjacent portions and has the maximum outer diameter, between one of the pair of side surface adjacent portions and the outermost diameter portion, and the pair of side surface adjacent portions. It is provided with at least one recessed portion arranged between the other portion and the outermost diameter portion, and the outermost diameter portion in the circumferential view of the piston ring. The contour line of is a curve having a center of curvature, and the center of curvature is arranged radially inside the common tangent line of the contour line of the side surface adjacent portion and the contour line of the outermost diameter portion. Further, in the circumferential view of the piston ring, the contour line of the at least one recessed portion is a curve having a center of curvature, and the center of curvature is arranged radially outside the common tangent line. Has been done. According to the piston ring according to the present invention, oil consumption can be reduced.

In the piston ring according to the present invention, the dimensional difference H between the outermost radial edge of the outermost diameter portion and the outermost radial edge of the side surface is preferably H ≦ 0.25 mm.

In the piston ring according to the present invention, the angle θ1 on the acute angle side formed by the axis and the common tangent on one side of the pair of side surface adjacent portions is θ1 ≦ 50 ° in the circumferential direction of the piston ring. Is preferable.

In the piston ring according to the present invention, the angle θ2 on the acute angle side formed by the axis and the common tangent on the other side of the pair of side surface adjacent portions is θ2 ≦ 60 ° in the circumferential direction of the piston ring. Is preferable.

In the piston ring according to the present invention, the angle θ1 can be set to the angle θ2 or less.

In the piston ring according to the present invention, in the circumferential direction of the piston ring, between the one of the pair of side surface adjacent portions and the outermost diameter portion of the outer peripheral surface, and the pair of side surfaces of the outer peripheral surface. The contour lines of the pair of side surface adjacent portions, the contour lines of the recessed portion, and the contour lines of the outermost diameter portion, between at least one of the other adjacent portion and the outermost diameter portion, are respectively. , The radius of curvature R1 of the outermost diameter portion, the radius of curvature R2 of the recessed portion, and the radius of curvature R3 of the side surface adjacent portion are R2 / R1 ≦ 4.5 and R2, respectively. It is preferable to satisfy the condition of / R3 ≦ 4.5.

In the piston ring according to the present invention, the radius of curvature R1 of the outermost diameter portion is preferably R1 ≦ 0.12 mm.

In the piston ring according to the present invention, the piston ring is preferably a side rail of an oil ring.

In the piston ring according to the present invention, when the piston ring is an oil ring, the oil ring includes two side rails arranged at intervals, and the outer peripheral surface of the piston ring has the two side rails. It can be the outer peripheral surface of at least one of the side rails.

In the piston ring according to the present invention, the piston ring can be a compression ring.

In the piston ring according to the present invention, the recessed portion of the contour line forming the outer peripheral surface of the piston ring can be symmetrical up and down in the axial direction.

In the piston ring according to the present invention, it is preferable that a hard coating layer or a resin coating layer is provided on the outer peripheral surface of the piston ring.

According to the present invention, it is possible to provide a piston ring capable of reducing oil consumption.

It is one side sectional view of the piston which can incorporate various piston rings which can be used as the piston ring which concerns on this invention. It is a top view which shows the oil ring from the side surface with the side rail which is 1st Embodiment of the piston ring which concerns on this invention. It is a top view which shows the side rail which constitutes a part of the oil ring shown in FIG. 2 from the side surface. It is sectional drawing which shows the AA cross section of FIG. FIG. 5 is a cross-sectional view of a main part showing a state in which the piston incorporating the oil ring of FIG. 2 is arranged inside the cylinder, corresponding to the cross section of BB of FIG. It is an enlarged sectional view of FIG. FIG. 6 is an enlarged cross-sectional view of FIG. It is sectional drawing which shows the outer peripheral surface of the side rail of FIG. 4 enlarged. It is sectional drawing which shows the outer peripheral surface of the conventional side rail enlarged. FIG. 5 is a cross-sectional view schematically showing a state in which oil is diffused by the outer peripheral surface of the side rail of FIG. 3 during the piston ascending stroke. It is sectional drawing which shows roughly the state which the oil is diffused by the outer peripheral surface of the conventional side rail at the time of a piston ascending stroke. It is a side rail which is the 2nd Embodiment of the piston ring which concerns on this invention, and is the enlarged sectional view which shows the side rail in the region corresponding to FIG. It is a side rail which is the 3rd Embodiment of the piston ring which concerns on this invention, and is the enlarged sectional view which shows the side rail in the region corresponding to FIG.

Hereinafter, various embodiments of the piston ring according to the present invention will be described with reference to the drawings. In the following description, the "axis line" means the "axis line O of the piston ring". Further, the "axial direction" means a "direction extending along the axis", that is, a "direction extending along the axis O". Further, the "radial direction" means a "direction orthogonal to the axial direction", that is, a "direction orthogonal to a direction extending along the axis O". Further, the "circumferential direction" means a "direction along the circumference of the axis", that is, a "direction along the circumference of the axis O".

FIG. 1 shows a piston ring to which these various piston rings can be incorporated together with various piston rings that can be used as the piston ring according to the present invention in a cross section on one side. In FIG. 1, reference numeral 100 is a piston used in an internal combustion engine (for example, a gasoline engine).

Reference numerals 10 to 30 are various piston rings that can be used as the piston ring according to the present invention. In this example, reference numeral 10 is an oil ring provided with a side rail, which is an embodiment of the piston ring according to the present invention. The oil ring 10 is incorporated into a ring groove 101 formed on the outer peripheral surface of the piston 100.

Reference numerals 20 and 30 are compression rings (pressure rings), respectively. Specifically, the compression ring 20 is a top ring. Further, the compression ring 30 is a second ring. The compression rings 20 and 30 are incorporated into the ring grooves 102 and 103 formed on the outer peripheral surface of the piston 100, respectively.

Hereinafter, the piston ring according to the present invention will be described with reference to the oil ring 10.

In this example, the oil ring 10 is a 3-piece type oil ring. The oil ring 10 includes a pair of side rails (oil ring rails) 11 and a spacer expander 12 according to an embodiment of the present invention. The two side rails 11 are arranged on the combustion chamber side and the crank chamber side of the engine (not shown) at intervals in the axial direction. In this example, the pair of side rails 11 each have the same configuration as each other.

FIG. 2 shows the oil ring 10 from the side surface. Further, FIG. 3 shows the side rail 11 from the side surface.

According to the present invention, the piston ring extends around the axis. In the present embodiment, as shown in FIG. 2, the oil ring 10 is a combination of the side rail 11 and the spacer 12, and as shown in FIG. 3, the side rail 11 extends around the axis O. ing. The side rail 11 according to the present embodiment is formed in a split ring shape having a joint 11c by bending a long, flat steel material (steel material). That is, the side rail 11 according to the present embodiment is formed in a C shape in which a part thereof in the circumferential direction is cut and the cut portion becomes a joint opening 11c. On the other hand, in this example, as will be described later, the spacer expander 12 presses and urges the side rail 11 outward in the radial direction to press and urge the inner peripheral surface 201 of the cylinder 200 (when the cylinder liner is provided, the cylinder liner The amount of oil adhering to the wall surface (inner peripheral surface) can be controlled.

Further, according to the present invention, the piston ring has two side surfaces facing each other in the axial direction. FIG. 4 is a cross-sectional view taken along the line AA of FIG. In the present embodiment, as shown in FIG. 4, the side rail 11 includes two side surfaces facing each other in the axial direction. In the present embodiment, the side rail 11 includes a first side surface 111 and a second side surface 112. The first side surface 111 and the second side surface 112 extend around the axis O, respectively. In the present embodiment, as described above, the first side surface 111 and the second side surface 112 of the side rail 11 are each formed in a C shape in which a part thereof is cut in the circumferential direction and the cut portion becomes a joint opening 11c. ing. In the present embodiment, the first side surface 111 is a side surface facing one side in the axial direction (upper side in the drawing). The second side surface 112 is a side surface facing the other side in the axial direction (lower side in the drawing). In the present embodiment, the first side surface 111 and the second side surface 112 are parallel to each other in the radial direction (horizontal direction). In the present embodiment, the first side surface 111 and the second side surface 112 are formed on flat surfaces extending along the radial direction and the circumferential direction, respectively.

Further, in the present embodiment, the first side surface 111 and the second side surface 112 each have the same planar configuration.

In FIG. 4, reference numeral 111e1 is the outermost radial edge of the first side surface 111. Further, reference numeral 111e2 is the innermost edge in the radial direction of the first side surface 111. Further, reference numeral W1 is a radial width between the radial outermost edge 111e1 and the radial innermost edge 111e2 of the first side surface 111, that is, the radial width of the first side surface 111. Similarly, in FIG. 4, reference numeral 112e1 is the outermost radial edge of the second side surface 112. Further, reference numeral 112e2 is the innermost edge in the radial direction of the second side surface 112. Further, reference numeral W2 is a radial width between the radial outermost edge 112e1 and the radial innermost edge 112e2 of the second side surface 112, that is, the radial width of the second side surface 112.

In the present embodiment, the radial distance of the radial outermost edge 111e1 of the first side surface 111 from the axis O is equal to the radial distance of the radial outermost edge 112e1 of the second side surface 112 from the axis O. That is, in the present embodiment, the radial outermost edge 111e1 of the first side surface 111 and the radial outermost edge 112e1 of the second side surface 112 are arranged at the same position in the radial direction with respect to the axis O. It is configured in. Further, in the present embodiment, the radial distance of the radial innermost edge 111e2 of the first side surface 111 from the axis O is equal to the radial distance of the radial innermost edge 112e2 of the second side surface 112 from the axis. That is, in the present embodiment, the radial innermost edge 111e2 of the first side surface 111 and the radial innermost edge 112e2 of the second side surface 112 are arranged at the same position in the radial direction with respect to the axis O. It is configured in. That is, in the present embodiment, the radial width W1 of the first side surface 111 and the radial width W2 of the second side surface 112 are configured to have the same width and are arranged at the same position.

Further, the side rail 11 includes an outer peripheral surface 1 and an inner peripheral surface 2. The outer peripheral surface 1 and the inner peripheral surface 2 extend around the axis O, respectively. The outer peripheral surface 1 is a surface facing outward in the radial direction, which connects the outermost radial edge 111e1 of the first side surface 111 and the outermost radial edge 112e1 of the second side surface 112 in the axial direction. The inner peripheral surface 2 is a surface facing inward in the radial direction, which connects the innermost radial edge 111e2 of the first side surface 111 and the innermost radial edge 112e2 of the second side surface 112 in the axial direction. With reference to FIG. 4, in a state where the side rail 11 is viewed from the circumferential direction (hereinafter, also referred to as “side rail circumferential view)), the contour lines of the outer peripheral surface 1 and the inner peripheral surface 2 of the side rail 11 are Each is substantially uniform over the entire circumference.

FIG. 5 shows a state in which the piston 100 incorporating the oil ring 10 is arranged inside the cylinder 200, corresponding to the BB cross section of FIG. As shown in FIG. 5, in the present embodiment, in the oil ring 10, the first side surface 111 of the side rail 11 is directed toward the combustion chamber side, and the second side surface 112 of the side rail 11 is directed toward the crank chamber side. It is mounted in the ring groove 101 of the piston 100. Each of the outer peripheral surfaces 1 of the side rails 11 slidably presses the inner peripheral surface 201 of the cylinder 200.

The side rail 11 is elastically mounted in the ring groove 101 of the piston 100 via the spacer expander 12. That is, the spacer expander 12 can press and urge the inner peripheral surface 2 of the side rail 11 on the outer peripheral side in the radial direction by the elastic force generated by mounting the oil ring 10 in the ring groove 101 of the piston 100. it can. In this example, the spacer expander 12 urges the side rail 11 to expand its diameter outward in the radial direction. Therefore, if the oil ring 10 is interposed between the piston 100 and the cylinder 200 so that the spacer expander 12 is compressed inward in the radial direction, the outer peripheral surface 1 of the side rail 11 and the inner peripheral surface of the cylinder 200 are provided. By contacting with 201, the amount of oil adhering to the inner peripheral surface (wall surface) 201 of the cylinder 200 can be controlled. The spacer expander 12 is formed, for example, in an annular shape that can be elastically deformed in the radial direction. Examples of such a spacer expander 12 include those formed into a corrugated shape in the axial direction or the circumferential direction. The spacer expander 12 can be formed of a steel material or the like.

In FIG. 6, the outer peripheral surface 1 of the side rail 11 and its periphery are enlarged and shown. FIG. 6 shows the contour line of the outer peripheral surface 1 in the side rail circumferential direction view.

According to the present invention, the outer peripheral surface of the piston ring includes a pair of side surface adjacent portions adjacent to each of the two side surfaces of the piston ring. In the present embodiment, as shown in FIG. 6, the outer peripheral surface 1 of the side rail 11 is provided with the first side surface adjacent portion 3 on one side in the axial direction. The first side surface adjacent portion 3 is one of a pair of side surface adjacent portions. The first side surface adjacent portion 3 is adjacent to the first side surface 111 of the side rail 11. In the present embodiment, as shown in FIG. 6, the first side surface adjacent portion 3 is connected to the outermost radial edge 111e1 of the first side surface 111 in the radial direction. Further, in the present embodiment, as shown in FIG. 6, the outer peripheral surface 1 of the side rail 11 is provided with a second side surface adjacent portion 4 on the other side in the axial direction. The second side surface adjacent portion 4 is the other of the pair of side surface adjacent portions. The second side surface adjacent portion 4 is adjacent to the second side surface 112 of the side rail 11. As shown in FIG. 6, the second side surface adjacent portion 4 is connected to the outermost radial edge 112e1 of the second side surface 112 in the radial direction.

Further, according to the present invention, the outer peripheral surface of the piston ring is provided between a pair of side surface adjacent portions and has an outermost diameter portion having a maximum outer diameter. In the present embodiment, as shown in FIG. 6, the outer peripheral surface 1 of the side rail 11 includes the outermost diameter portion 6. As shown in FIG. 6, the outermost diameter portion 6 is arranged between the first side surface adjacent portion 3 and the second side surface adjacent portion 4. Further, as shown in FIG. 6, the outermost diameter portion 6 has a maximum outer diameter D at the outermost radial edge e6 of the outermost diameter portion 6. In the present embodiment, as shown in FIG. 6, the outermost radial edge e6 of the outermost diameter portion 6 is located at the central position P1 in the axial direction between the first side surface 111 and the second side surface 112 of the side rail 11. It is configured to be placed in.

Further, according to the present invention, the outer peripheral surface of the piston ring is between one of the pair of side surface adjacent portions and the outermost diameter portion, and between the other of the pair of side surface adjacent portions and the outermost diameter portion. It has at least one recess arranged between the two. In the present embodiment, as shown in FIG. 6, the outer peripheral surface 1 of the side rail 11 is provided with one first recessed portion 7 on one side in the axial direction. The first recessed portion 7 is arranged between the first side surface adjacent portion 3 and the outermost diameter portion 6. In the present embodiment, the first recessed portion 7 is connected to the first side surface adjacent portion 3 on the inner side in the radial direction and is connected to the outermost diameter portion 6 on the outer side in the radial direction. Further, in the present embodiment, as shown in FIG. 6, the outer peripheral surface 1 of the side rail 11 is provided with one second recessed portion 8 on the other side in the axial direction. The second recessed portion 8 is arranged between the second side surface adjacent portion 4 and the outermost diameter portion 6. In the present embodiment, the second recessed portion 8 is connected to the second side surface adjacent portion 4 on the inner side in the radial direction and is connected to the outermost diameter portion 6 on the outer side in the radial direction.

Further, according to the present invention, the contour line of the outermost diameter portion is a curve having a center of curvature in the circumferential direction of the piston ring. In the present embodiment, as shown in FIG. 6, the contour line L6 of the outermost diameter portion 6 is a curve having a center of curvature O6 in the side rail circumferential direction view. In this embodiment, the curve is formed with a radius of curvature r6.

Further, according to the present invention, in the circumferential view of the piston ring, the center of curvature of the contour line of the outermost diameter portion is in the radial direction from the common tangent line of the contour line of the side surface adjacent portion and the contour line of the outermost diameter portion. It is located inside.

In the present embodiment, when viewed from the first side surface 111 side of the side rail 11 (hereinafter, also referred to as “first side surface side”), the center of curvature O6 is, as shown in FIG. 6, in the side rail circumferential direction. The contour line L3 of the first side surface adjacent portion 3 and the contour line L6 of the outermost diameter portion 6 are arranged radially inside the common tangent line L1. In the present embodiment, as shown in FIG. 6, the contour line L3 of the first side surface adjacent portion 3 is a curve having a center of curvature O3 in the side rail circumferential direction view. In the present embodiment, the curve is formed with a radius of curvature r3. Further, in the present embodiment, as shown in FIG. 6, the common tangent line L1 is the contact point A1 with the contour line L3 of the first side surface adjacent portion 3 and the contour line of the outermost diameter portion 6 in the side rail circumferential direction view. It is a tangent line passing through the contact point B1 with L6. Further, in the present embodiment, as shown in FIG. 6, the center of curvature O6 is arranged radially inside the common tangent line L1 together with the center of curvature O3 in the side rail circumferential direction view.

On the other hand, in the present embodiment, when viewed on the second side surface 112 side (hereinafter, also referred to as “second side surface side”) of the side rail 11, the center of curvature O6 is a side rail as shown in FIG. In the circumferential view, the contour line L4 of the second side surface adjacent portion 4 and the contour line L6 of the outermost diameter portion 6 are arranged radially inside the common tangent line L2. In the present embodiment, as shown in FIG. 6, the contour line L4 of the second side surface adjacent portion 4 is a curve having a center of curvature O4 in the side rail circumferential direction view. In the present embodiment, the curve is formed with a radius of curvature r4. Further, in the present embodiment, as shown in FIG. 6, the common tangent line L2 is the contact point A2 with the contour line L4 of the second side surface adjacent portion 4 and the contour line of the outermost diameter portion 6 in the side rail circumferential direction view. It is a tangent line passing through the contact point B2 with L6. Further, in the present embodiment, as shown in FIG. 6, the center of curvature O6 is arranged radially inside the common tangent line L2 together with the center of curvature O4 in the side rail circumferential direction view.

Further, according to the present invention, the contour line of the recessed portion is a curve having a center of curvature in the circumferential direction of the piston ring. Further, the center of curvature is arranged radially outside the common tangent line.

Looking at the first side surface side of the side rail 11 in the present embodiment, in the present embodiment, as shown in FIG. 6, the contour line L7 of the first recessed portion 7 is the curvature center O7 in the side rail circumferential direction view. It is a curve having. In this embodiment, the curve is formed with a radius of curvature r7. Further, as shown in FIG. 6, the center of curvature O7 is arranged radially outside the common tangent line L1 in the side rail circumferential direction view.

On the other hand, in the present embodiment, when viewed from the second side surface side of the side rail 11, in the present embodiment, as shown in FIG. 6, the contour line L8 of the second recessed portion 8 is viewed in the circumferential direction of the side rail. Is a curve having a center of curvature O8. In this embodiment, the curve is formed with a radius of curvature r8. Further, as shown in FIG. 6, the center of curvature O8 is arranged radially outside the common tangent line L2 in the side rail circumferential direction view. Here, the radius of curvature r7 of the first recessed portion 7 and the radius of curvature r8 of the second recessed portion 8 are such that the contour line L7 of the first recessed portion 7 and the contour line L8 of the second recessed portion 8 are axes, respectively. The radii may be the same so as to be symmetrical in the vertical direction.

FIG. 7 is an enlarged cross section of FIG. FIG. 7 shows the outer peripheral surface 1 of the side rail 11 on the first side surface side of the side rail 11, in other words, the outer peripheral surface 1 on the combustion chamber side. As shown in FIG. 7, in the present embodiment, on the first side surface side of the side rail 11, one side of the contour line L7 of the first recessed portion 7 in the extending direction is the contour line L3 of the first side surface adjacent portion 3. It is directly connected. In the present embodiment, the contour line L7 of the first recessed portion 7 has the same tangent line as the contour line L3 of the first side surface adjacent portion 3 at the connection point with the contour line L3 of the first side surface adjacent portion 3. ing. As a result, in the present embodiment, the contour line L7 of the first recessed portion 7 and the contour line L3 of the first side surface adjacent portion 3 are smoothly connected. However, according to the present invention, the contour line L3 of the first side surface adjacent portion 3 and the contour line L7 of the first recessed portion 7 can be connected, for example, via a straight contour line without being directly connected. .. Further, the other side of the contour line L7 of the first recessed portion 7 in the extending direction is directly connected to the contour line L6 of the outermost diameter portion 6. In the present embodiment, the contour line L7 of the first recessed portion 7 has the same tangent line as the contour line L6 of the outermost diameter portion 6 at the connection point with the contour line L6 of the contour line L6 of the outermost diameter portion 6. Have. As a result, in the present embodiment, the contour line L7 of the first recessed portion 7 and the contour line L6 of the outermost diameter portion 6 are smoothly connected. However, according to the present invention, the contour line L7 of the first recessed portion 7 and the contour line L6 of the outermost diameter portion 6 can be connected, for example, via a straight contour line without being directly connected.

Similarly, with reference to FIG. 7, of the outer peripheral surface 1 of the side rail 11, the second side surface side of the side rail 11, in other words, the outer peripheral surface 1 on the crank chamber side will be described. When FIG. 7 is viewed as an enlarged cross-sectional view of the outer peripheral surface 1 on the crank chamber side, as shown in FIG. 7, in the present embodiment, the second side surface side of the side rail 11 is the same as the first side surface side of the side rail 11. On the second side surface side of the side rail 11, one side of the contour line L8 of the second recessed portion 8 in the extending direction is directly connected to the contour line L4 of the second side surface adjacent portion 4. In the present embodiment, the contour line L8 of the second recessed portion 8 has the same tangent line as the contour line L4 of the second side surface adjacent portion 4 at the connection point with the contour line L4 of the second side surface adjacent portion 4. ing. As a result, in the present embodiment, the contour line L8 of the second recessed portion 8 and the contour line L4 of the second side surface adjacent portion 4 are smoothly connected. However, according to the present invention, the contour line L4 of the second side surface adjacent portion 4 and the contour line L8 of the second recessed portion 8 can be connected, for example, via a straight contour line without being directly connected. .. Further, the other side of the contour line L8 of the second recessed portion 8 in the extending direction is directly connected to the contour line L6 of the outermost diameter portion 6. In the present embodiment, the contour line L8 of the second recessed portion 8 has the same tangent line as the contour line L6 of the outermost diameter portion 6 at the connection point with the contour line L6 of the contour line L6 of the outermost diameter portion 6. Have. As a result, in the present embodiment, the contour line L8 of the second recessed portion 8 and the contour line L6 of the outermost diameter portion 6 are smoothly connected. However, according to the present invention, the contour line L8 of the second recessed portion 8 and the contour line L6 of the outermost diameter portion 6 can be connected, for example, via a straight contour line without being directly connected.

As described above, the oil ring is used to control the amount of oil adhering to the inner peripheral surface 201 of the cylinder 200. Therefore, it is preferable that the surface pressure of the side rail 11 with respect to the cylinder 200 is higher.

FIG. 8A is an enlarged cross-sectional view showing the outer peripheral surface 1 of the side rail 11 according to the present embodiment. FIG. 8A shows the effective barrel amount EB of the side rail 11. The effective barrel amount EB contributes to the oil scraping action. In order to increase the surface pressure of the side rail 11 with respect to the cylinder 200, it is preferable to secure a large effective barrel amount EB. When the contour line L6 of the outermost diameter portion 6 is a curve formed by the radius of curvature r6 as in the present invention, in order to secure a large effective barrel amount EB, the radius of curvature r6 of the outermost diameter portion 6 is set. It is effective to design it small.

On the other hand, FIG. 8B is an enlarged cross-sectional view showing the outer peripheral surface 61 of the conventional side rail 60. As shown in FIG. 8B, the outer peripheral surface 61 of the side rail 60 does not have a recessed portion. When the radius of curvature r66 of the outermost diameter portion 66 is designed to be small in the side rail 60, the distance between the outermost diameter portion 66 and the first side surface 661 and the distance between the outermost diameter portion 66 and the second side surface 662 are respectively. In order to connect smoothly, a larger angle θ6 with respect to the axial direction is set as shown in FIG. 8B. That is, in the conventional side rail 60, when the radius of curvature r66 is kept small, the radial outermost edge 661e1 of the first side surface 661 and the radial outermost edge 662e2 of the second side surface 662 are from the inner peripheral surface 201 of the cylinder 200. Is also located inwardly separated in the radial direction. As a result, according to the conventional side rail 60, for example, between the radial outermost edge 661e1 of the first side surface 661 and the radial outermost edge e66 of the outermost diameter portion 66 on the first side surface side of the side rail 60. The dimensional difference H of is large. When the dimensional difference H on the first side surface side of the side rail 60 becomes large, as shown in FIG. 8B, an inclined surface between the first side surface adjacent portion 63 and the outermost diameter portion 66 of the outer peripheral surface 61 of the side rail 60. Reference numeral 67 denotes a large inclined surface having an angle θ6, which is contoured by a common tangent line L61 between the contour line L63 of the first side surface adjacent portion 63 and the contour line L66 of the outermost diameter portion 66. Therefore, in the case of the conventional side rail 60, the oil present on the first side surface side of the side rail 60 when the piston 100 rises toward the combustion chamber side (hereinafter, also referred to as “piston rising stroke”). Is scattered toward the combustion chamber side from the inner peripheral surface 201 side of the cylinder 200 by the inclined surface 67 of the outer peripheral surface 61 of the side rail 60, and is carried to the combustion chamber. Therefore, the conventional side rail 60 causes an increase in oil consumption when trying to increase the surface pressure on the cylinder 200 for the purpose of improving the oil scraping action.

On the other hand, in the conventional side rail 60, in order to reduce the dimensional difference H, it is necessary to increase the radius of curvature r66 of the outermost diameter portion 66. However, in the conventional side rail 60, if the radius of curvature r66 of the outermost diameter portion 66 is set large, the axial direction of the effective sliding contact surface (the surface defined by the effective barrel amount EB) of the outer peripheral surface 61 of the side rail 60. Since the width is widened, the surface pressure is significantly reduced due to the progress of wear. Therefore, in the conventional side rail 60, if the radius of curvature r66 of the outermost diameter portion 66 is set large, the performance of the side rail 11 tends to deteriorate over time.

That is, the conventional side rail 60 has not been able to reduce the oil consumption while increasing the surface pressure on the cylinder 200.

On the other hand, as shown in FIG. 8A, the side rail 11 according to the present embodiment includes a first recessed portion 7 between the outermost diameter portion 6 of the side rail and the first side surface 111. In this case, even if the radius of curvature r6 of the outermost diameter portion 6 is set small in order to increase the surface pressure on the cylinder 200, the dimensional difference H on the first side surface side of the side rail 11 is the largest in the first recessed portion 7. By being recessed inward in the radial direction between the outer diameter portion 6 and the first side surface 111, it can be kept small. That is, in the side rail 11 according to the present embodiment, the angle θ1 of the common tangent line L1 between the contour line L3 of the first side surface adjacent portion 3 and the contour line L6 of the outermost diameter portion 6 of the side rail is the conventional side rail 60. It can be suppressed to be smaller than the angle θ6 of the inclined surface 67 of.

That is, according to the side rail 11 according to the present embodiment, by reducing the radius of curvature r6 of the outermost diameter portion 6, the surface pressure on the cylinder 200 can be increased and the dimensional difference H (angle θ1) can be suppressed to be small. Therefore, the amount of oil consumed due to the scattering of oil to the combustion chamber side can be reduced.

As shown in FIG. 6, in the side rail 11 according to the present embodiment, the contour line L6 of the outermost diameter portion 6 on the outer peripheral surface 1 of the side rail 11 is a curve having a center of curvature O6 in the side rail circumferential direction view. The center of curvature O6 is located radially inward of the common tangents L1 and L2. In this case, the outermost diameter portion 6 can be formed into a protrusion formed with a desired radius of curvature. Therefore, as shown in FIG. 5, the surface pressure can be set high with respect to the inner peripheral surface 201 of the cylinder 200, and the effect of scraping off the oil is excellent, so that the oil consumption can be reduced.

Explaining the above in more detail, referring to FIG. 5, when the oil is scraped from the crank chamber side (lower side in the middle of FIG. 5), the side rail 11 of the oil ring 10 is scraped from the crank chamber side. The oil is evenly adhered to the inner peripheral surface 201 of the cylinder 200 toward the combustion chamber side. At this time, if the oil is scattered to the combustion chamber side, the scattered oil is sent to the combustion chamber side together with the combustion gas flowing back to the combustion chamber side (upper side in FIG. 5), so that the oil is released. There is a concern that it will be burned on the combustion chamber side together with the combustion gas. FIG. 9B schematically shows a state in which oil is diffused by the outer peripheral surface 61 of the conventional side rail 60. For example, as shown in FIG. 9B, when the inclined surface 67 of the outer peripheral surface 61 of the side rail 60 has a linear tapered shape, the direction OD at which the oil is scattered by the side rail 60 is the side toward the combustion chamber ( It will be oriented toward the side along the axis O). Therefore, it is effective to reduce the oil consumption of the side rail of the oil ring by preventing the oil from scattering to the combustion chamber side when the oil is scraped up.

On the other hand, as shown in FIG. 6, in the side rail 11 according to the present embodiment, the contour line L7 of the first recessed portion 7 and the contour line L8 of the second recessed portion 8 are respectively viewed in the circumferential direction of the piston ring. The curve has the center of curvature O7 and the curve has the center of curvature O8, and the centers of curvature O7 and O8 are located radially outside the common tangents L1 and L2, respectively. FIG. 9A schematically shows a state in which oil is diffused by the outer peripheral surface 1 of the side rail 11 according to the present embodiment. In this case, as shown by the arrow in FIG. 9A, when the oil is scraped up toward the combustion chamber side (upper center in FIG. 9A), the direction OD in which the oil is scattered by the side rail 11 forms the first recess 7. Depending on the curvature of the contour line L7, the side rail 11 can be oriented radially outward, that is, toward the inner peripheral surface 201 of the cylinder 200. Therefore, according to the side rail 11 according to the present embodiment, when the oil is scattered by the side rail 11, it is possible to prevent the oil from being sent to the combustion chamber. As a result, the amount of oil consumed due to the scattering of oil can be reduced.

As described above, according to the side rail 11 according to the present embodiment, the oil consumption can be reduced in consideration of the surface pressure and the scattering of the oil. Therefore, according to the side rail 11 according to the present embodiment, the reduction in oil consumption is further improved.

Further, referring to FIG. 6, in the present embodiment, the dimensional difference H between the radial outermost edge e6 of the outermost diameter portion 6 and the radial outermost edge 111e1 of the first side surface 111 is H ≦ 0.25 mm. It is preferable to have. More preferably, 0.01 mm ≦ H ≦ 0.25 mm, and more preferably 0.05 mm ≦ H ≦ 0.25 mm.

If the dimensional difference H on the first side surface side of the side rail 11 is 0.25 mm or less, the scattering of oil to the combustion chamber side during the piston ascending stroke is efficiently suppressed, which is effective in reducing oil consumption. is there. Further, in order to form the optimum outermost diameter portion 6, the recessed portion 7, and the side surface adjacent portion 3, the dimensional difference H may be 0.01 mm or more, more preferably 0.05 mm ≦ H ≦ 0. If it is set to 25 mm, the oil consumption due to the scattering of oil can be surely reduced while efficiently maintaining the performance of the side rail 11.

Further, referring to FIG. 6, in the present embodiment, in the side rail circumferential direction view, the angle on the acute angle side formed by the axis O of the side rail 11 and the common tangent line L1 on the first side surface side (hereinafter, “the first”. Also referred to as “1 angle”) θ1 is preferably θ1 ≦ 50 °. Further, the lower limit of the angle θ1 is 2 ° to 6 °, preferably 5 ° ≦ θ1 ≦ 50 °. Here, the axis O of the side rail 11 may be a straight line orthogonal to the side surfaces 111 and 112 (diameter direction) of the side rail 11 and passing through the outermost radial edge e6 of the outermost diameter portion 6. it can.

In this example, as shown in FIG. 5, the oil ring 10 is mounted on the piston 100 so that the first side surface 111 of the side rail 11 faces the combustion chamber side. That is, in the piston ascending stroke, it is necessary that the outer peripheral surface 1 on the first side surface side of the side rail 11 mainly forms an appropriate lubricating oil film on the inner peripheral surface 201 of the cylinder 200. On the other hand, if the first angle θ1 on the first side surface side is too large, there is a concern that the amount of scattered oil will increase as the oil is scraped up. For example, when the first angle θ1 exceeds 50 °, such a concern becomes greater.

On the other hand, referring to FIG. 6, when the first angle θ1 on the first side surface side is too small, when the side rail 11 is tilted due to the swing phenomenon of the piston 100 during operation, the first side surface adjacent portion 3 becomes There is a risk of collision with the wall surface of the inner peripheral surface 201 of the cylinder 200. If this contact occurs when the piston is raised, the oil adhering to the inner peripheral surface 201 (wall surface) of the cylinder 200 is scraped up and the oil consumption is deteriorated. Such a risk is significantly reduced (for example, when the first angle θ1 is 5 ° or more).

Therefore, if the first angle θ1 on the first side surface side of the outer peripheral surface 1 of the side rail 11 is θ1 ≦ 50 °, more preferably 5 ° ≦ θ1 ≦ 50 °, the amount of oil consumed due to oil scattering. Can be effectively reduced.

Further, in the present embodiment, the angle on the acute angle side (hereinafter, also referred to as “second angle”) θ2 formed by the axis O of the side rail 11 and the common tangent line L2 on the second side surface side in the side rail circumferential direction view. Is preferably θ2 ≦ 60 °. Further, the angle θ2 is preferably 10 ° ≦ θ2 ≦ 60 °. Here, too, the axis O of the side rail 11 may be a straight line that is orthogonal to the side surfaces 111 and 112 (diameter direction) of the side rail 11 and passes through the outermost radial edge e6 of the outermost diameter portion 6. it can.

In this example, as shown in FIG. 5, the oil ring 10 is mounted on the piston 100 so that the second side surface 112 of the side rail 11 faces the crank chamber side. That is, in this example, the second side surface 112 of the side rail 11 mainly exerts its function when the side rail 11 scrapes off excess oil adhering to the inner peripheral surface 201 of the cylinder 200 toward the crank chamber side. It will be. On the other hand, if the second angle θ2 on the second side surface side is too large, the oil scraping effect is small. For example, when the second angle θ2 exceeds 60 °, such a concern becomes greater.

If the second angle θ2 on the second side surface side is too small, the space area (volume) formed by the outer peripheral surface 1 of the side rail 11 and the inner peripheral surface 201 of the cylinder 200 becomes smaller, and the piston lowering stroke (piston lowering stroke). (During the process in which the piston 100 descends toward the crank chamber side), the oil pressure tends to rise, which leads to an increase in oil, and there is a concern that the effect of scraping off the oil cannot be sufficiently exhibited. Such concerns are kept small, for example, when the second angle θ2 is 10 ° or more.

Therefore, if the second angle θ2 on the second side surface side is θ2 ≦ 60 °, more preferably 10 ° ≦ θ2 ≦ 60 °, the oil consumption can be effectively reduced while efficiently scraping the oil. Can be reduced to.

By the way, according to the present invention, the first angle θ1 on the first side surface side and the second angle θ2 on the second side surface side can be the same angle or different angles. That is, in the present embodiment, the first angle θ1 on the first side surface side can be equal to or less than the second angle θ2 on the second side surface side.

In this case, on the first side surface side (first angle θ1 side) of the outer peripheral surface 1 of the side rail 11, the oil consumption amount due to the oil scattering at the time of oil scraping is emphasized, and the oil consumption amount is reduced. Further, on the second side surface side (second angle θ2 side) of the outer peripheral surface 1 of the side rail 11, the oil consumption can be reduced while efficiently scraping off the oil.

Further, according to the present invention, the first recessed portion 7 of the contour line L7 and the second recessed portion 8 of the contour line L8 forming the outer peripheral surface 1 of the side rail 11 are axes in the side rail circumferential direction, respectively. It can be symmetrical up and down in the direction. In this case, since it is not necessary to determine the vertical position of the side rail 11 (determine the orientation of the first side surface 111 and the second side surface 112 of the side rail 11) when mounting the side rail 11 on the piston, the work efficiency can be improved. In the present embodiment, the center of curvature O7 of the first recessed portion 7 and the center of curvature O7 of the second recessed portion 7 are located symmetrically in the axial direction. Further, in the present embodiment, the first angle θ1 on the first side surface side and the second angle θ2 on the second side surface side are equal angles. Further, in the present embodiment, the radius of curvature r7 of the first recessed portion 7 and the radius of curvature r8 of the second recessed portion 8 have the same radius.

Further, in the present embodiment, in the side rail circumferential direction view, between the first side surface adjacent portion 3 and the outermost diameter portion 6 of the outer peripheral surface 1, and the second side surface adjacent portion 4 and the outermost portion of the outer peripheral surface 1. The contour line L3 of the first side surface adjacent portion 3, the contour line L7 of the first recessed portion 7, and the contour line L6 of the outermost diameter portion 6 between the outer diameter portion 6 and at least one of them, and , The contour line L4 of the second side surface adjacent portion 4, the contour line L8 of the second recessed portion 8, and the contour line L6 of the outermost diameter portion 6 are curves having a center of curvature, respectively, and the curvature of the outermost diameter portion 6 The radius R1, the radius of curvature R2 of the first recessed portion 7 and the second recessed portion 8, and the radius of curvature R3 of the first side surface adjacent portion 3 and the second side surface adjacent portion 4 are R2 / R1 ≦ 4.5, respectively, and It is preferable to satisfy the condition of R2 / R3 ≦ 4.5.

In this case, on the first side surface side of the outer peripheral surface 1 of the side rail 11, the dimensions of the radius of curvature r6 of the outermost diameter portion 6, the radius of curvature r7 of the first recessed portion 7, and the radius of curvature r3 of the first side surface adjacent portion 3 are set. , Respectively, by setting based on a certain relationship by R1 to R3, and on the second side surface side of the outer peripheral surface 1 of the side rail 11, the radius of curvature r6 of the outermost diameter portion 6 and the second recessed portion 8 By setting the dimensions of the radius of curvature r8 and the radius of curvature r8 of the second side surface adjacent portion 4 based on a certain relationship by R1 to R3, respectively, the surface pressure while efficiently maintaining the performance of the side rail 11. And the oil consumption due to the scattering of the oil can be easily reduced.

Further, in the present embodiment, the radius of curvature R1 (= r6) of the outermost diameter portion 6 is preferably R1 ≦ 0.12 mm. Further, the radius of curvature R1 is 0.01 mm ≦ R1 ≦ 0.12 mm, more preferably 0.04 mm ≦ R1 ≦ 0.12 mm.

In order to increase the surface pressure of the side rail 11 with respect to the cylinder 200, it is effective to reduce the radius of curvature r6 of the outermost diameter portion 6. On the contrary, if the radius of curvature r6 of the outermost diameter portion 6 is too large, as described above, it is assumed that the surface pressure is significantly reduced due to the progress of wear, which is not practical. On the other hand, for example, when the radius of curvature r6 of the outermost diameter portion 6 is 0.12 mm or less, it can be adopted in most types of internal combustion engines (for example, gasoline engines) on the market.

On the other hand, when the radius of curvature r6 of the outermost diameter portion 6 is less than 0.01 mm, the workability when manufacturing the side rail 11 deteriorates.

Therefore, if the radius of curvature R1 (= r6) of the outermost diameter portion 6 is R1 ≦ 0.12 mm, more preferably 0.01 mm ≦ R1 ≦ 0.12 mm, the radius of curvature r6 of the outermost diameter portion 6 By setting the dimensions to a certain numerical range, it is possible to reliably and easily reduce the oil consumption due to the surface pressure in a wider applicable range.

By the way, the second recess 8 arranged between the second side surface 112 of the side rail 11 and the outermost diameter portion 6 is closely related to the oil scraping effect when the piston is lowered. According to the present invention, by increasing the space between the inner peripheral surface 201 of the cylinder 200 formed by the second recessed portion 8, the oil that stays when the piston is lowered is less likely to be compressed, and the generation of flood control is avoided. Can be done. Further, in this case, the oil scraping effect can be improved by reducing the amount of oil rising along the inner peripheral surface 201 of the cylinder 200. FIG. 10 is a side rail 11 which is a second embodiment of the piston ring according to the present invention, and is an enlarged cross-sectional view showing the side rail 11 in a region corresponding to FIG. Hereinafter, the same reference numerals are used for substantially the same parts as those of other embodiments.

As shown in FIG. 10, in the present embodiment, the radial outermost edge 111e1 of the first side surface 111 is radially outer than the radial outermost edge 112e1 of the second side surface 112 in the radial direction with respect to the axis O. It is configured to be placed at the position of. That is, in the present embodiment, the radial width W1 of the first side surface 111 is configured to be wider than the radial width W2 of the second side surface 112. In particular, in the present embodiment, as shown in FIG. 10, in the side rail circumferential direction view, the contour line L8 of the second recessed portion 8 is a linear contour extending along the outermost diameter portion 6 and the radial direction. It is connected via line L91. Therefore, as shown in FIG. 10, in the present embodiment, the second recessed portion 8 has an undercut portion 91 formed by the contour line L91 with respect to the outermost diameter portion 6 in the side rail circumferential direction view. Is forming.

Further, FIG. 11 is a side rail 11 which is a third embodiment of the piston ring according to the present invention, and is an enlarged cross-sectional view showing the side rail 11 in a region corresponding to FIG.

As shown in FIG. 11, in the present embodiment, as in the second embodiment, the radial outermost edge 111e1 of the first side surface 111 is the radial outermost edge of the second side surface 112 in the radial direction with respect to the axis O. It is configured to be arranged at a position radially outside the outer edge 112e1. That is, in the present embodiment, the radial width W1 of the first side surface 111 is configured to be wider than the radial width W2 of the second side surface 112. In particular, in the present embodiment, as shown in FIG. 11, the contour line L6 of the outermost diameter portion 6 is a curve close to a circle in the side rail circumferential direction view. Therefore, the contour line L8 of the second recessed portion 8 is connected to the outermost diameter portion 6 by a contour line L92 that is curved so as to bite into the first side surface side of the outermost diameter portion 6. That is, as shown in FIG. 11, in the present embodiment, the second recessed portion 8 forms an underhook portion 9 formed by the contour line L92 with respect to the outermost diameter portion 6b in the side rail circumferential direction view. doing.

The piston ring according to the present invention may be an oil ring 10. In this case, the oil consumption can be reduced in consideration of the surface pressure and the scattering of the oil.

By the way, in the present embodiment, the oil ring 10 includes two side rails 11 arranged at intervals. According to the present embodiment, the outer peripheral surface of the piston ring according to the present invention can be the outer peripheral surface 1 of at least one of the two side rails 11.

In each of the above embodiments, both of the two side rails 11 have an outer peripheral surface of the piston ring according to the present invention. As shown in FIG. 6, in the first embodiment, the outer peripheral surface 1 of the side rail 11 has a planar configuration in which the combustion chamber side and the crank chamber side of the engine are the same (in the first embodiment, the first recessed portion). 7 and the second recessed portion 8 have a planar configuration) that is vertically symmetrical in the axial direction. As shown in FIG. 10, in the second embodiment, the outer peripheral surface 1 of the side rail 11 has a planar configuration in which the combustion chamber side and the crank chamber side of the engine are different from each other. As shown in FIG. 11, in the third embodiment, as in the second embodiment, the outer peripheral surfaces 1 of the two side rails 11 have a planar configuration in which the combustion chamber side and the crank chamber side of the engine are different from each other. ing.

However, according to the present invention, the configurations of the outer peripheral surfaces 1 can be combined as appropriate. For example, the outer peripheral surface 1 of FIG. 6 can be adopted as the outer peripheral surface of one side rail 11 of the two side rails 11, and the outer peripheral surface 1 of FIG. 10 can be adopted as the outer peripheral surface of the other side rail 11. Alternatively, the outer peripheral surface 1 of FIG. 6 can be adopted as the outer peripheral surface of one side rail 11 of the two side rails 11, and the outer peripheral surface 1 of FIG. 11 can be adopted as the outer peripheral surface of the other side rail 11. Alternatively, the outer peripheral surface 1 of FIG. 10 can be adopted as the outer peripheral surface of one side rail 11 of the two side rails 11, and the outer peripheral surface 1 of FIG. 11 can be adopted as the outer peripheral surface of the other side rail 11.

By the way, in the present invention, the piston ring means to include an endless or endless sealing member capable of sliding on an arbitrary surface while sealing the surface. That is, in the piston ring according to the present invention, the piston ring can be the side rail 11 of the oil ring 10 as in each of the above-described embodiments. In this case, the oil ring 10 according to each of the above-described embodiments can be easily manufactured by providing versatility applicable to the existing oil ring.

By the way, it is preferable to provide a hard coating layer or a resin coating layer on the outer peripheral surface of the piston ring according to the present invention. As a specific example, in each of the above-described embodiments, a hard coating layer or a resin coating layer can be provided on the oil ring 10, that is, the outer peripheral surface 1 of the side rail 11. As the hard coating layer or the resin coating layer, for example, a configuration including at least one of a nitriding treatment layer, a PVD treatment layer, a hard chrome plating treatment layer, and a DLC layer can be adopted. In this case, the wear of the outer peripheral surface 1 of the side rail 11 and particularly the wear of the outermost diameter portion 6 are prevented for a long period of time, so that the performance of the oil ring 10 is efficiently maintained and the oil consumption is reduced. It can be reduced.

Further, as described above, the piston ring according to the present invention can be the compression rings 20 and 30 shown in FIG. In this case, it is possible to provide a compression ring capable of reducing oil consumption in consideration of surface pressure and oil scattering. Further, according to the present invention, the hard coating layer or the resin coating layer as described above can be provided on the outer peripheral surface of the compression ring. Also in this case, wear of the outer peripheral surface 1 of the compression ring, particularly wear of the outermost diameter portion 6, is prevented for a long period of time.

The above has only disclosed some embodiments of the present invention, and various modifications can be made according to the claims. For example, in each of the above-described embodiments, one first recessed portion 7 is arranged between the first side surface adjacent portion 3 and the outermost diameter portion 6, but the first recessed portion 7 is in the axial direction. Multiple can be arranged along. The same applies to the second recessed portion 8, and in each of the above-described embodiments, one second recessed portion 8 is arranged between the second side surface adjacent portion 4 and the outermost diameter portion 6, but the second recessed portion 8 is arranged. A plurality of recessed portions 8 can also be arranged along the axial direction. When a plurality of the first recessed portion 7 and the second recessed portion 8 are arranged, the number of the first recessed portion 7 and the second recessed portion 8 is preferably the same, but can be different.

The various configurations adopted in each of the above-described embodiments and examples can be used in combination with each other. In addition, the various configurations adopted in each of the above-described embodiments and examples can be appropriately replaced with each other.

The following table shows the data when Examples 1 to 3 of the present invention and Comparative Example 1 were prototyped and actually tested. In Examples 1 to 3, side rails 11 are used, and in Comparative Example 1, only the first side surface side of the outer peripheral surface of the side rails extending in the axial direction is chamfered. It was used. The test was carried out with a 1.5 L 4-cylinder gasoline engine driven at full throttle (rotation speed 6000 rpm). In each of the examples and the comparative examples, the top ring and the second ring are performed by using a common ring, and the oil consumption (LOC: Lubricating Oil Consumption) is the amount of oil stored before the engine is operated and the engine. It was calculated by measuring the amount of oil stored after the operation. Assuming that the oil consumption of Comparative Example 1 was 1, the ratio of the oil consumption to each of Examples 1 to 3 was calculated.

R1 in the table is the radius of curvature r6 of the outermost diameter portion 6. R2 is the radius of curvature r7 of the first recessed portion 7. R3 is the radius of curvature r3 of the first side surface adjacent portion 3. Further, H in the table is a dimensional difference between the radial outermost edge e6 of the outermost diameter portion 6 and the radial outermost edge 111e1 of the first side surface 111. The unit of R1 to R3 and H is "mm" (millimeter), respectively. Further, θ1 in the table is a first angle between the first side surface adjacent portion 3 and the outermost diameter portion 6. The unit of θ1 is "°" (degree). The "sliding position" in the table is an axial position in which the outermost diameter portion of the side rail is arranged with respect to the outer peripheral surface of the side rail.

In Examples 1 to 3 and Comparative Example 1, the plate thickness of the side rail was set to 0.35 mm, respectively, and in Examples 1 to 3 and Comparative Example 1, the radius of curvature of the first side surface adjacent portion was set to 0.35 mm, respectively. R3 = 0.1 mm. The ratio (R2 / R1) of the recessed portion R2 of Examples 1 to 3 to the radius of curvature R1 of the outermost diameter portion was 4.3, 1 and 2, respectively. Here, in order to clarify the presence or absence of the first recess and the effect of the invention of its size R2 / R1, all the sliding positions are centered, and the outermost radial edge of the outermost diameter portion and the radial direction of the side surface are all centered. The experiment was carried out by fixing the dimensional difference H from the outermost edge to 0.2 mm and the value of the inclination degree θ1 (40 °) of the concave contour line of the first recessed portion. The results are shown in Table 1.

With reference to Table 1 above, in Examples 1 to 3, the oil consumption was reduced to 27 to 61% as compared with Comparative Example 1 having no recessed portion.

1: Outer peripheral surface, 3: First side surface adjacent part (one of the pair of side surface adjacent parts), O3: Center of curvature, R3, r3: Diameter of curvature, 4: Second side surface adjacent part (the other of the pair of side surface adjacent parts) , O4: center of curvature, R3, r4: radius of curvature, 6: outermost diameter, O6: center of curvature, R1, r6: radius of curvature, e6: outermost radial edge of outer diameter, 7: first recess (Recessed part), O7: Center of curvature, R2, r7: Radius of curvature, 8: Second dented part (recessed part), O8: Center of curvature, R2, r8: Diameter of curvature, 10: Oil ring (piston ring), 11: Side rail (piston ring), 12: Spacer, 20: Compression ring, 30: Compression ring, H: Dimensional difference, L1: 1st common tangent line, L2: 2nd common tangent line, θ1: 1st angle, θ2: 2nd angle, 40: Oil ring, 41: Integrated side rail, 43: Side rail part, 44: Web part, 45: Mounting groove, 111: 1st side surface (side surface), 111e1: 1st side surface in radial direction Outer edge (radial outermost edge of side surface), 112: second side surface (side surface), 112e1: radial outermost edge of second side surface (radial outermost edge of side surface)

Claims (12)

A piston ring that extends around the axis
The outer peripheral surface of the piston ring is
A pair of side-to-side adjoining portions adjacent to each of the two sides of the piston ring,
An outermost diameter portion that is arranged between the pair of side surface adjacent portions and has a maximum outer diameter,
At least arranged between one of the pair of side surface adjacent portions and the outermost diameter portion, and between the other of the pair of side surface adjacent portions and the outermost diameter portion. One dent and
Is equipped with
In the circumferential view of the piston ring, the contour line of the outermost diameter portion is a curve having a center of curvature, and the center of curvature is the contour line of the side surface adjacent portion and the outermost diameter portion. It is arranged radially inside the common tangent line with the contour line, and further
In the circumferential view of the piston ring, the contour line of the at least one recess is a curve having a center of curvature, and the center of curvature is arranged radially outside the common tangent line. .. The piston ring according to claim 1, wherein the dimensional difference H between the outermost radial edge of the outermost diameter portion and the outermost radial edge of the side surface is H ≦ 0.25 mm. The acute-angled angle θ1 formed by the axis and the common tangent on one side of the pair of side surface adjacent portions in the peripheral view of the seal ring is θ1 ≦ 50 °, according to claim 1 or 2. Piston ring. Any of claims 1 to 3, wherein the angle θ2 on the acute angle side formed by the axis and the common tangent on the other side of the pair of side surface adjacent portions in the peripheral view of the piston ring is θ2 ≦ 60 °. The piston ring according to item 1. The piston ring according to any one of claims 1 to 4, wherein the angle θ1 is equal to or less than the angle θ2. In the peripheral view of the piston ring, between the one of the pair of side surface adjacent portions and the outermost diameter portion of the outer peripheral surface, and the other and the most of the pair of side surface adjacent portions of the outer peripheral surface. The contour lines of the pair of side surface adjacent portions, the recessed portion, and the contour lines of the outermost diameter portion between the outer diameter portion and at least one of the outer diameter portions are curves having a center of curvature, respectively. ,
The radius of curvature R1 of the outermost diameter portion, the radius of curvature R2 of the recessed portion, and the radius of curvature R3 of the side surface adjacent portion are respectively.
R2 / R1 ≤ 4.5 and R2 / R3 ≤ 4.5
The piston ring according to any one of claims 1 to 5, which satisfies the condition of. The piston ring according to any one of claims 1 to 6, wherein the radius of curvature R1 of the outermost diameter portion is R1 ≦ 0.12 mm. The piston ring according to any one of claims 1 to 7, wherein the piston ring is a side rail of an oil ring. The oil ring has two side rails that are spaced apart from each other.
The piston ring according to claim 8, wherein the outer peripheral surface of the piston ring is the outer peripheral surface of at least one of the two side rails. The piston ring according to any one of claims 1 to 7, wherein the piston ring is a compression ring. The piston ring according to any one of claims 1 to 10, wherein the recessed portion of the contour line forming the outer peripheral surface of the piston ring is symmetrical up and down in the axial direction. The piston ring according to any one of claims 1 to 11, wherein a hard coating layer or a resin coating layer is provided on the outer peripheral surface of the piston ring.

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