WO2022219831A1 - Space expander and oil ring - Google Patents

Abstract

This space expander comprises: an expander body that is annularly formed along the circumferential direction of an oil ring and that urges a pair of segments outward in the radial direction of the oil ring, the expander body including a pair of abutment ends that form an abutment by facing each other and, and the expander body being formed in a wavy shape that is continuous in the circumferential direction when viewed in the radial direction of the oil ring; an expander groove formed in the expander body so as to span between the abutments and extend along the circumferential direction of the oil ring; and a linear member including a fitting part formed in an arc along the circumferential direction of the oil ring, the fitting part being fitted into the expander groove so as to span between the abutments.

Description

Space expander and oil ring

The present invention relates to a spacer expander and an oil ring in which a segment and a spacer expander are combined.

An internal combustion engine mounted on a general automobile adopts a configuration in which a piston ring including a compression ring (pressure ring) and an oil ring is mounted in the ring groove of the piston. In the axial direction of the piston, the compression ring is provided on the combustion chamber side, and the oil ring is provided on the crank chamber side. The oil ring has an oil seal function that suppresses the outflow of oil to the combustion chamber side by scraping off excess engine oil (lubricating oil) adhering to the inner wall surface of the cylinder to the crank chamber side, and a lubricating oil film. By adjusting the amount of oil so that it is properly retained on the inner wall surface of the cylinder, it has the function of preventing seizure of the piston due to operation of the internal combustion engine. The compression ring has a gas seal function that suppresses the outflow (blow-by) of combustion gas from the combustion chamber side to the crank chamber side by maintaining airtightness, and scrapes off excess oil that the oil ring could not scrape off. It has an oil seal function that suppresses oil rise.

Here, the oil ring is a three-piece combination oil that combines a pair of segments (also called side rails) that slide on the inner wall surface of the cylinder and a spacer expander that urges the pair of segments against the inner wall surface of the cylinder. Rings are widely used. In relation to such a combination oil ring, there is disclosed a combination oil ring provided with a spacer expander in which a plurality of wavy periodic elements displaced in the axial direction are connected in the circumferential direction (for example, Patent Document 1: ). When assembling a three-piece combination oil ring to a piston, the spacer expander is mounted in the ring groove and then the segment is mounted in the ring groove. When installing the spacer expander in the ring groove, insert the spacer expander into the ring groove while widening the gap of the spacer expander. do.

WO2013/069349 Japanese Utility Model Laid-Open No. 56-85048 Japanese Utility Model Laid-Open No. 1-25448 Japanese Utility Model Laid-Open No. 3-38456 Japanese Utility Model Laid-Open No. 60-18242

When a conventional axially wavy (wavy shape continuous in the circumferential direction when viewed in the radial direction of the oil ring) spacer expander is mounted in the ring groove of the piston, the abutment ends overlap in the radial or axial direction of the oil ring. There is a risk of becoming. In such a state, there is concern that it will be difficult to assemble the segments. Moreover, even if the segment can be assembled, there is a concern that the segment cannot be properly applied with an urging force, and the function as an oil ring cannot be exhibited. For example, the segment may hit the upper and lower surfaces of the ring groove and the segment may not protrude toward the inner wall of the cylinder.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an oil ring provided with an axially wavy spacer expander, in which it is possible to prevent the abutment ends of the spacer expanders from overlapping each other. It is to provide technology.

In order to solve the above problems, the present invention employs the following configuration. That is, the present invention provides a spacer expander that is provided between a pair of segments that are spaced apart in the axial direction of the oil ring in an oil ring that is assembled to a piston in an internal combustion engine. An expander body that is annularly formed along and urges the pair of segments outward in the radial direction of the oil ring, and includes a pair of abutment ends that face each other to form an abutment, An expander body formed in a wavy shape that is continuous in the circumferential direction when viewed in the radial direction of the oil ring; An expander groove and a linear fitting portion formed in an arc shape along the circumferential direction of the oil ring, the fitting portion being fitted in the expander groove so as to straddle the abutment. A spacer expander comprising: a member.

According to the present invention, by maintaining the expander main body in a posture in which the pair of abutment ends face each other by the linear member, it is possible to prevent the pair of abutment ends from overlapping each other in the radial direction and the axial direction. As a result, it is possible to prevent the segment from becoming difficult to assemble in the operation of assembling the oil ring to the piston and prevent the oil ring assembled to the piston from failing to exhibit its function. Furthermore, since the axially wavy spacer expander has a narrow axial width and a narrow radial thickness, it is difficult to provide a hole for inserting a linear member. A structure is adopted in which the fitting portion is fitted by providing a groove in the bottom. This makes it possible to prevent the pair of abutment ends from overlapping each other even though it is an axially wavy spacer expander.

Further, in the present invention, the expander main body includes a plurality of upper pieces arranged at intervals along the circumferential direction of the oil ring, and a plurality of upper pieces arranged at intervals on the oil ring when the oil ring is assembled to the piston. A plurality of lower pieces provided so as to be positioned closer to the crank chamber in the internal combustion engine than the plurality of upper pieces in the axial direction, each of the lower pieces being positioned in the circumferential direction of the oil ring relative to the upper piece. a plurality of lower pieces arranged alternately with each other; and a plurality of connecting pieces connecting the upper pieces and the lower pieces that are adjacent to each other in the circumferential direction of the oil ring, wherein the upper pieces is an upper base portion and an upper segment provided upright on the inner side of the upper base portion in the radial direction of the oil ring, and the upper segment provided on the combustion chamber side of the internal combustion engine of the pair of segments is the diameter of the oil ring. the lower piece is formed upright on the inside of the lower base portion and the lower base portion in the radial direction of the oil ring; a lower ear portion that presses a lower segment provided on the crank chamber side of the internal combustion engine radially outward of the oil ring.

Further, in the present invention, the expander grooves are provided at the outer end portion of the plurality of connecting pieces, which is the radially outer end portion of the oil ring, so as to be arranged along the circumferential direction of the oil ring. A plurality of notches are formed on the outer peripheral surface of the expander body, and the width of the fitting portion in the axial direction of the oil ring is larger than the width of the outer end portion of the connecting piece in the axial direction. It can be small. Thereby, the fitting portion can be fitted to the outer peripheral surface of the expander main body.

Further, in the present invention, the expander grooves are provided at inner end portions of the plurality of connecting pieces, which are radially inner end portions of the oil ring, so as to be arranged along the circumferential direction of the oil ring. A plurality of notches are formed on the inner peripheral surface of the expander body, and the width of the fitting portion in the axial direction of the oil ring is greater than the width of the inner end portion of the connecting piece in the axial direction. may be smaller. Thereby, the fitting portion can be fitted to the inner peripheral surface of the expander main body.

Further, in the present invention, the expander groove is formed on the outer peripheral surface of the expander main body, and in a free state before the oil ring is assembled to the piston, the expander groove is formed at the inner peripheral end of the fitting portion. The radius of curvature of the arc may be less than or equal to the radius of curvature of the outermost circumference of the expander main body when the abutment ends are in contact with each other. According to this, when the radius of curvature of the arc at the inner peripheral end of the fitting portion is less than the radius of curvature at the outermost periphery of the expander main body, the fitting portion is fitted into the expander groove so that the fitting portion is fitted into the expander groove. Since the diameter of the portion is expanded, self-tension is generated in the linear member to reduce the diameter. As a result, in the spacer expander, the inner peripheral end portion of the fitting portion presses the expander main body radially inward. Thereby, it is possible to maintain a state in which the fitting portion is fitted in the expander groove across the joint.

Further, in the present invention, the expander groove is formed on the inner peripheral surface of the expander main body, and in a free state before the oil ring is assembled to the piston, the expander groove is formed at the outer peripheral end of the fitting portion. The radius of curvature of the arc may be greater than or equal to the radius of curvature of the innermost circumference of the expander main body when the abutment ends are in contact with each other. According to this, when the radius of curvature of the outer peripheral edge of the fitting portion exceeds the radius of curvature of the innermost periphery of the expander main body, the fitting portion is fitted into the expander grooves, thereby shrinking the fitting portion. Since the diameter is increased, self-tension is generated in the linear member to increase the diameter. As a result, in the spacer expander, the outer peripheral end portion of the fitting portion presses the expander main body radially outward. Thereby, it is possible to maintain a state in which the fitting portion is fitted in the expander groove across the joint.

Further, in the present invention, the expander grooves are formed by a plurality of notches provided in the upper base portion of the plurality of upper pieces so as to be arranged along the circumferential direction of the oil ring, and A thickness of the fitting portion in the radial direction of the oil ring may be smaller than a thickness of the upper base portion in the radial direction. Thereby, the fitting portion can be fitted to the combustion chamber side surface of the expander main body.

Further, in the present invention, the expander groove is formed by a plurality of notches provided in the lower base portion of the plurality of lower pieces so as to be arranged along the circumferential direction of the oil ring, A thickness of the fitting portion in the radial direction of the oil ring may be smaller than a thickness of the lower base portion in the radial direction. As a result, the fitting portion can be fitted to the surface of the expander main body on the crank chamber side.

Further, in the present invention, the expander groove is formed on either one of both end surfaces of the expander main body in the axial direction of the oil ring, and the oil ring is in a free state before being assembled to the piston. wherein the radius of curvature of the arc at the outer peripheral end of the fitting portion is within +10% of the radius of curvature of the outermost periphery of the expander main body in a state where the pair of abutment ends are butted against each other, and Even if the radius of curvature of the arc at the inner peripheral end of the fitting portion is -10% or more of the radius of curvature of the innermost periphery of the expander main body when the pair of abutment ends are abutted against each other. good. As a result, it is possible to make it difficult for the fitting portion to come off the expander groove, and to reduce the resistance when the diameter of the expander main body is contracted or expanded. Further, when the radius of curvature of the arc at the outer peripheral end of the fitting portion exceeds the radius of curvature of the outermost periphery of the expander main body, the fitting portion is fitted into the expander groove to reduce the diameter of the fitting portion. Therefore, self-tension is generated in the linear member, and the outer peripheral end portion of the fitting portion presses the expander main body radially outward. As a result, the state in which the linear member is fitted in the expander groove across the joint is maintained. Similarly, when the radius of curvature of the arc at the inner peripheral end of the fitting portion is less than the radius of curvature of the innermost periphery of the expander main body, the linear member is fitted into the expander groove to is expanded in diameter, self-tension is generated in the linear member, and the inner peripheral end portion of the fitting portion presses the expander main body radially inward. As a result, the state in which the fitting portion is fitted in the expander groove across the gap is maintained.

Further, in the present invention, the expander groove is formed on the outer peripheral surface of the expander main body, the linear member further includes engaging portions provided at both ends of the fitting portion, and the The engaging portion includes a first bent portion bent from an end portion of the fitting portion and extending from the outer peripheral side to the inner peripheral side of the expander main body through between the connecting pieces that are adjacent in the circumferential direction; A second bent portion may be included which is bent from the tip of the first bent portion and engages with an inner end portion, which is a radially inner end portion of the oil ring, of the connecting piece. According to this configuration, the engaging portions provided at both ends of the fitting portion are engaged with the expander body, so that the linear member can be kept fitted to the expander body.

The present invention can also be specified as an oil ring in which a pair of segments and the spacer expander described above are combined. That is, the present invention is an oil ring comprising a pair of segments spaced apart in the axial direction of the oil ring and a spacer expander provided between the pair of segments, wherein the spacer expander is , an expander body formed in an annular shape along the circumferential direction of the oil ring and biasing the pair of segments outward in the radial direction of the oil ring, wherein the pair of expander bodies face each other to form an abutment; An expander body that includes an abutment end and is formed in a wave shape that is continuous in the circumferential direction when viewed in the radial direction of the oil ring, and the expander that extends along the circumferential direction of the oil ring across the abutment. An expander groove formed in the main body and a fitting portion formed in an arc shape along the circumferential direction of the oil ring, the fitting being fitted into the expander groove so as to straddle the gap. A linear member including a portion may be provided.

According to the present invention, in an oil ring provided with an axially wavy spacer expander, it is possible to prevent the abutment ends of the spacer expanders from overlapping each other.

1 is a partial cross-sectional view of an internal combustion engine provided with an oil ring according to an embodiment; FIG. It is a perspective view of a portion of the expander body according to the embodiment. FIG. 4 is a cross-sectional view for explaining outer and inner diameters of an expander body; It is a top view of the linear member which concerns on embodiment. FIG. 4 is a perspective view of a portion of a spacer expander according to an embodiment; FIG. 4 is a top view of a portion of a spacer expander according to an embodiment; FIG. 7 is a cross-sectional view taken along the line AA of FIG. 6; FIG. 4 is a partial cross-sectional view of an internal combustion engine provided with an oil ring according to Modification 1 of the embodiment; FIG. 5 is a top view of part of a spacer expander according to Modification 1 of the embodiment; FIG. 10 is a cross-sectional view taken along the line BB of FIG. 9; FIG. 7 is a partial cross-sectional view of an internal combustion engine including an oil ring according to Modification 2 of the embodiment; FIG. 11 is a partial cross-sectional view of an internal combustion engine provided with an oil ring according to Modification 3 of the embodiment; FIG. 11 is a partial cross-sectional view of an internal combustion engine provided with an oil ring according to Modification 4 of the embodiment; FIG. 11 is a partial cross-sectional view of an internal combustion engine provided with an oil ring according to Modification 5 of the embodiment; FIG. 11 is a partial cross-sectional view of an internal combustion engine provided with an oil ring according to Modification 6 of the embodiment; FIG. 11 is a partial cross-sectional view of an internal combustion engine provided with an oil ring according to Modification 7 of the embodiment; FIG. 21 is a top view of part of a spacer expander according to Modification 8 of the embodiment; FIG. 20 is a top view of a linear member according to Modification 8 of the embodiment;

Preferred embodiments of the present invention will be described below with reference to the drawings. It should be noted that the configurations described in the following embodiments are not meant to limit the technical scope of the invention only to them unless otherwise specified.

[overall structure]
FIG. 1 is a partial cross-sectional view of an internal combustion engine 100 provided with an oil ring 40 according to an embodiment. FIG. 1 shows a cross section orthogonal to the circumferential direction (peripheral direction) of the oil ring 40 . As shown in FIG. 1, in the internal combustion engine 100, a predetermined separation distance is secured between the inner wall surface 10a of the cylinder 10 and the outer peripheral surface 20a of the piston 20 mounted on the cylinder 10, so that the piston clearance PC1 is formed. formed. A ring groove 30 having a substantially rectangular cross section is formed in the outer peripheral surface 20 a of the piston 20 . The ring groove 30 connects an upper wall 301 formed on the combustion chamber side, a lower wall 302 formed on the crank chamber side and facing the upper wall 301, and inner peripheral edges of the upper wall 301 and the lower wall 302. wall 303; An oil ring 40 according to this embodiment is mounted in the ring groove 30 .

The oil ring 40 is a sliding member that slides on the inner wall surface 10a of the cylinder 10 as the piston 20 reciprocates. The oil ring 40 is a so-called three-piece combination oil ring, and includes a pair of segments 1, 1 and a spacer expander 2, as shown in FIG. The spacer expander 2 further includes an expander main body 3 , expander grooves 4 and linear members 5 . The oil ring 40 is attached to the piston 20 by being fitted into the ring groove 30 .

Hereinafter, as shown in FIG. 1, the direction (axial direction) along the central axis of the oil ring 40 is defined as "vertical direction". Further, in the axial direction of the oil ring 40, the combustion chamber side (upper side in FIG. 1) of the internal combustion engine 100 is defined as "upper side", and the opposite side, that is, the crank chamber side (lower side in FIG. 1) is defined as "upper side". defined as 'lower side'. In the following description of the oil ring 40, unless otherwise specified, the term "circumferential direction" refers to the circumferential direction of the oil ring 40, and the term "radial direction" refers to the radial direction of the oil ring 40. , “axial direction” refers to the axial direction of the oil ring 40 . Further, in this specification, the state in which the oil ring is attached to the piston attached to the cylinder of the internal combustion engine as shown in FIG. 1 is referred to as the "used state". Also, the state before the oil ring is attached to the piston is called a "free state." More specifically, the free state is a state in which the oil ring is disassembled into components of the segment, the expander body, and the linear member, and each of these components is not constrained by other elements. refers to state. Each configuration of the oil ring 40 will be described below.

[segment]
The pair of segments 1, 1 are annularly formed along the circumferential direction of the oil ring 40, and are provided independently of each other and spaced apart in the axial direction. In the oil ring 40 according to the embodiment, the pair of segments 1, 1 have the same shape. However, according to the present invention, the shape of the pair of segments may be different. Hereinafter, when a pair of segments 1, 1 are separately referred to, the segment 1 provided on the upper side (combustion chamber side) will be referred to as an upper segment 1U, and the segment 1 provided on the lower side (crank chamber side) will be referred to as a lower segment 1U. It is called side segment 1L. When not distinguishing between them, they are simply referred to as segment 1. The material of the segment 1 is not particularly limited. Examples of materials for the segment 1 include SUS and SWRH.

As shown in FIG. 1, the segment 1 has an outer peripheral surface 11, an inner peripheral surface 12, an upper surface 13, and a lower surface 14. The width of the segment 1 in the axial direction is defined by the upper surface 13 and the lower surface 14 . The upper segment 1U is provided so that the upper surface 13 faces the upper wall 301 of the ring groove 30 in use. The lower segment 1L is provided so that the lower surface 14 faces the lower wall 302 of the ring groove 30 in use.

[Spacer expander]
As shown in FIG. 1, the spacer expander 2 is provided between a pair of segments 1, 1, and includes an expander body 3 formed in a wave shape in the axial direction and an expander body 3 formed in the expander body 3. An expander groove 4 and a linear member 5 fitted in the expander groove 4 are provided.

The expander main body 3 is annularly formed along the circumferential direction of the oil ring 40 . The expander body 3 includes an outer peripheral surface S1, an inner peripheral surface S2, an upper surface S3, and a lower surface S4. The upper surface S<b>3 is a surface arranged on the upper side (combustion chamber side) of the axial end surfaces of the expander body 3 . The lower surface S<b>4 is a surface arranged on the lower side (crank chamber side) of the axial end surfaces of the expander main body 3 . In other words, the expander main body 3 is provided so that the upper surface S3 faces the upper segment 1U and the lower surface S4 faces the lower segment 1L when in use. The material of the expander main body 3 is not particularly limited. Examples of the material of the expander main body 3 include SUS.

FIG. 2 is a perspective view of part of the expander main body 3 according to the embodiment. As shown in FIG. 2, the expander main body 3 is configured by a plurality of wavy periodic elements that are displaced in the axial direction and are connected in the circumferential direction. In other words, the expander main body 3 is formed in a wave shape that is continuous in the circumferential direction when viewed in the radial direction of the oil ring 40 (when viewed from the radially outer or inner side). Specifically, the expander main body 3 includes a plurality of upper pieces 31 and lower pieces 32 that are alternately arranged in the circumferential direction while being spaced apart in the axial direction and the circumferential direction, and upper pieces 31 and lower pieces that are adjacent in the circumferential direction. and a connecting piece 33 that connects with 32 . The plurality of upper pieces 31 are arranged at intervals along the circumferential direction. The plurality of lower pieces 32 are provided so as to be positioned below the plurality of upper pieces 31 when the oil ring 40 is assembled to the piston 20 (that is, in the state of use). Also, the plurality of lower pieces 32 are arranged so that each of the lower pieces 32 and each of the upper pieces 31 are alternately arranged in the circumferential direction. The upper piece 31 and the lower piece 32 are provided so as to be orthogonal to the axial direction, and are separated from each other in the axial direction. The connecting piece 33 connects the circumferentially adjacent ends of the upper piece 31 and the lower piece 32 . Further, as shown in FIG. 2, the expander main body 3 includes a pair of abutment ends 3a and 3b that face each other to form an abutment G1. In addition, the structure of the expander main body according to the present invention is not limited to this, and may be formed in a wave shape in the axial direction.

As shown in FIG. 1 , the upper piece 31 includes an upper base portion 310 , upper ear portions 311 and upper support portions 312 . The upper base portion 310 extends radially perpendicular to the axial direction. The upper ear portion 311 is formed upright inside the upper base portion 310 in the radial direction and protrudes upward with respect to the upper base portion 310 . In addition, the upper ear portion 311 presses the upper segment 1U radially outward by coming into contact with the inner peripheral surface 12 of the upper segment 1U in use. The upper support portion 312 is formed upright on the outer side of the upper base portion 310 in the radial direction and protrudes upward with respect to the upper base portion 310 . Further, the upper support portion 312 supports the upper segment 1U by coming into contact with the lower surface 14 of the upper segment 1U in use. A through hole 34 is formed at the base of the upper ear portion 311 . Note that the upper piece according to the present invention may not have the upper support portion 312 .

As shown in FIG. 1, the lower piece 32 includes a lower base portion 320, a lower ear portion 321, and a lower support portion 322. The lower base portion 320 extends radially perpendicular to the axial direction. The lower ear portion 321 is formed upright inside the lower base portion 320 in the radial direction and protrudes downward with respect to the lower base portion 320 . In addition, the lower ear portion 321 presses the lower segment 1L radially outward by coming into contact with the inner peripheral surface 12 of the lower segment 1L in use. The lower support portion 322 is formed upright on the outer side of the lower base portion 320 in the radial direction and protrudes downward with respect to the lower base portion 320 . Further, the lower support portion 322 supports the lower segment 1L by coming into contact with the upper surface 13 of the lower segment 1L in use. A through hole 34 is formed at the base of the lower ear portion 321 . Note that the lower piece according to the present invention may not have the lower support portion 322 .

Here, reference E1 in FIG. 1 indicates the radially outer end (outer end) of the connecting piece 33, and reference E2 indicates the radially inner end (inner end) of the connecting piece 33. Also, let b1 be the width of the outer end E1 in the axial direction, and b2 be the width of the inner end E2 in the axial direction. At this time, as shown in FIG. 1, in this example, b1 is equal to the distance in the axial direction between the lower surface of the upper support portion 312 and the upper surface of the lower support portion 322, and b2 is the distance between the lower surface of the upper ear portion 311 and the lower ear. It is equal to the distance in the axial direction from the upper surface of the portion 321 . Also, the thickness of the upper base portion 310 in the radial direction is a1, and the thickness of the lower base portion 320 in the radial direction is a2. At this time, as shown in FIG. 1, in this example, a1 is equal to the distance in the radial direction between the upper ear portion 311 and the upper support portion 312, and a2 is the distance in the radial direction between the lower ear portion 321 and the lower support portion 322. equal to the distance in

In addition, as shown in FIGS. 1 and 2, the outer end E1 of the connecting piece 33 is formed with a notch 37 that opens radially outward (peripheral side). The inner wall of the notch 37 is formed in an arcuate shape that protrudes radially inward. However, the shape of the notch according to the present invention is not limited to an arc shape. The cutouts 37 are provided in the plurality of connecting pieces 33 so as to be arranged along the circumferential direction. As a result, expander grooves 4 extending in the circumferential direction and opening to the outer peripheral side are formed in the outer peripheral surface S1 of the expander main body 3 . The expander groove 4 is formed including a plurality of notches 37, and extends across the gap G1 as shown in FIG. The expander grooves 4 according to the embodiment are formed over the entire circumference of the expander main body 3 . However, the expander grooves according to the present invention are not limited to this. The expander groove may be formed in at least a part of the expander main body so as to straddle the gap. In this example, the expander groove 4 is formed in the center of the connecting piece 33 in the axial direction. good.

FIG. 3 is a cross-sectional view for explaining the outer diameter and inner diameter of the expander main body 3. FIG. Reference numeral CA3 in FIG. 3 indicates the central axis of the expander main body 3 . At this time, the outer diameter of the expander main body 3, that is, the curvature radius of the outermost periphery of the expander main body 3 (the distance from the central axis CA3 of the expander main body 3 to the outer peripheral surface S1) is defined as R1, and the inner diameter of the expander main body 3 is The circumference, that is, the radius of curvature of the innermost circumference of the expander main body 3 (the distance from the central axis CA3 of the expander main body 3 to the inner peripheral surface S2) is defined as R2. That is, R1 is the outer diameter of the expander main body 3, and R2 is the inner diameter of the expander main body 3. As shown in FIG.

FIG. 4 is a top view (viewed from above in the axial direction) of the linear member 5 according to the embodiment. The linear member 5 is a linear member formed by bending a wire. Although the material of the linear member 5 is not particularly limited, it can be made of steel or resin. Examples of materials for the linear member 5 include SUS, SWP, and resin. The linear member 5 includes a fitting portion 51 and a locking portion 52 . The fitting portion 51 is formed in an arc shape along the circumferential direction of the oil ring 40 and extends along the circumferential direction of the oil ring 40 . As shown in FIG. 1 , the fitting portion 51 has a circular cross-sectional shape corresponding to the cross-sectional shape of the expander groove 4 formed in the expander main body 3 . However, the present invention is not limited to this. The cross-sectional shape of the notch 37 and the cross-sectional shape of the linear member 5 may not necessarily be the same. Moreover, the cross-sectional shape of the linear member 5 may not be circular. Further, the width w1 of the fitting portion 51 in the axial direction is the width b1 of the outer end portion E1 of the connecting piece 33 in the axial direction, that is, the distance between the lower surface of the upper support portion 312 and the upper surface of the lower support portion 322 in the axial direction. less than distance.

As shown in FIG. 4, the engaging portion 52 is connected to one end portion of the fitting portion 51 and is bent so as to protrude radially inward. The locking portion 52 includes a first bent portion 521 extending radially inward from one end portion of the fitting portion 51 and a second bent portion 522 bent from the tip of the first bent portion 521 and extending radially outward. include. The second bent portion 522 includes one end of the linear member 5 .

Here, reference numeral 511 in FIG. 4 indicates the outer peripheral edge of the fitting portion 51 of the linear member 5 . The outer peripheral end portion 511 is a portion of the outer peripheral surface of the fitting portion 51 and is a portion of the fitting portion 51 that is positioned radially outward most. Further, reference numeral 512 indicates an inner peripheral end portion of the fitting portion 51 of the linear member 5 . The inner peripheral end portion 512 is a portion of the inner peripheral surface of the fitting portion 51 and is a portion of the fitting portion 51 that is positioned radially inward. Reference C5 indicates the center of the arc formed by the fitting portion 51. As shown in FIG. At this time, the radius of curvature of the linear member 5 at the outer peripheral end portion 511 of the fitting portion 51 (distance from the center C5 of the arc of the fitting portion 51 to the outer peripheral end portion 511) is r1, and the inner periphery of the fitting portion 51 is Let r2 be the radius of curvature of the linear member 5 at the end portion 512 (the distance from the center C5 of the arc of the fitting portion 51 to the inner peripheral end portion 512).

FIG. 5 is a perspective view of part of the spacer expander 2 according to the embodiment. FIG. 5 shows a state in which the pair of abutment ends 3a and 3b are butted against each other (contacted). As shown in FIG. 5, in the spacer expander 2, the fitting portion 51 of the linear member 5 is fitted in the expander groove 4 of the expander main body 3 so as to straddle the gap G1. The fitting portion 51 and the expander groove 4 are loosely fitted.

At this time, in the spacer expander 2 according to this example, in the free state, the curvature radius r2 of the arc at the inner peripheral end portion 512 of the fitting portion 51 of the linear member 5 projects the pair of abutment end portions 3a and 3b. The dimensions of R1 and r2 are set so that the radius of curvature of the outermost periphery of the expander main body 3 in the contact state is equal to or less than R1. As a result, the linear member 5 can be fitted in the expander groove 4 . Here, when the dimension of r2 is less than the dimension of R1, the diameter of the linear member 5 is expanded by fitting the linear member 5 into the expander groove 4, so that the linear member 5 is contracted. A self-tension occurs that tends to break. As a result, in the spacer expander 2 in which the linear member 5 is fitted in the expander groove 4, the inner peripheral end portion 512 of the linear member 5 presses the expander main body 3 radially inward. As a result, the state in which the linear member 5 is fitted in the expander groove 4 across the gap G1 is maintained. At this time, the curvature radius r2 of the linear member 5 in the free state is 0 to -10% of the curvature radius R1 of the expander main body 3 in the state in which the pair of abutment ends 3a and 3b abut against each other in the free state. is preferably within the range of , and more preferably within the range of 0 to -5%. This makes it difficult for the linear member 5 to come off the expander groove 4 .

FIG. 6 is a top view of part of the spacer expander 2 according to the embodiment. As shown in FIG. 6 , in the spacer expander 2 , the locking portion 52 of the linear member 5 is engaged with one of the plurality of connecting pieces 33 so that the linear member 5 is attached to the expander main body 3 . Locked. In this example, the locking portion 52 is engaged with the connecting piece 33 on the side of the abutment end 3a of the pair of abutment ends 3a and 3b sandwiching the abutment G1. Note that the locking portion 52 may be engaged with the connecting piece 33 on the side of the abutment end portion 3b. Here, reference G2 in FIG. 6 indicates the gap between the connecting pieces 33 adjacent in the circumferential direction. As shown in FIG. 6, in the spacer expander 2, the first bent portion 521 connected to the end portion of the fitting portion 51 extends from the outer peripheral surface S1 side of the expander main body 3 through the gap G2 to the inner peripheral side on the opposite side. The second bent portion 522 extending to the surface S2 side and connected to the first bent portion 521 is folded back and extends from the inner peripheral surface S2 side to the outer peripheral surface S1 side on the opposite side through the adjacent gap G2. . As a result, the connecting piece 33 is sandwiched between the first bent portion 521 and the second bent portion 522 from both sides in the circumferential direction. Also, the tip of the second bent portion 522 abuts on the connecting piece 33 and does not protrude to the outer peripheral side of the expander main body 3 . Here, FIG. 7 is a sectional view showing the AA section of FIG. As shown in FIG. 7 , a notch 38 into which the locking portion 52 is fitted is formed in the inner end portion E2 of the connecting piece 33 corresponding to the bent portion of the locking portion 52 . This prevents the linear member 5 from protruding to the inner peripheral side of the expander main body 3 . However, the linear member 5 may protrude toward the inner peripheral side of the expander body 3 as long as it does not interfere with (contact with) the inner wall of the ring groove 30, and the notch 38 is not formed in the expander body 3. It's good. In the spacer expander 2, the fitting portion 51 is fitted into the expander groove 4 formed on the outer peripheral surface S1 side of the expander main body 3, and the engaging portion 52 is formed on the inner peripheral surface S2 side of the expander main body 3. The linear member 5 is restricted from moving relative to the expander main body 3 in the radial direction by fitting into the cutout 38 . In the spacer expander 2, the connecting piece 33 on the side of the abutment end 3a is sandwiched between the first bent portion 521 and the second bent portion 522 from both sides in the circumferential direction. Since the tip of the second bent portion 522 is in contact with 33, relative movement of the linear member 5 with respect to the abutment end portion 3a in the circumferential direction is restricted. As a result, one end portion (locking portion 52 ) of the linear member 5 is locked on the abutment end portion 3 a side of the expander main body 3 , thereby preventing the linear member 5 from coming off the expander main body 3 . On the other hand, the other end of the linear member 5 is not locked on the abutment end 3 b side of the expander body 3 . Therefore, in the spacer expander 2, the abutment end portion 3b is slidable along the fitting portion 51 in the circumferential direction. At least one of the expander grooves 4 is provided on the side of the abutment end 3b so that the fitting portion 51 does not come off the expander groove 4 when the abutment end 3b is slid along the fitting portion 51 in the circumferential direction. The opening of the notch 37 may be closed with resin, for example.

At least one surface of the segment 1 and the expander body 3 is coated with a resin coating, a nitriding coating, a Ni-P plating coating, a chromium plating coating, a PVD coating, or a DLC coating. A coating may be formed that includes at least one of the layers. In addition, a "resin film" refers to a film formed of a resin material. A "nitriding coating" refers to a coating formed by infiltrating nitrogen into a metal surface by nitriding. Further, "Ni--P plating film" refers to a film formed by electroless Ni--P plating. In addition, the term "chromium-plated film" refers to a film formed by chromium plating. Chrome plating is also called industrial chrome plating. Also, the term "PVD (physical vapor deposition) treated coating" refers to a coating formed by the PVD method. A "DLC (Diamond Like Carbon) treated coating" refers to an amorphous hard carbon coating mainly composed of hydrocarbons and allotropes of carbon. By forming such a coating, the wear resistance of the segment 1 or the expander main body 3 can be enhanced.

[Assembling the oil ring to the piston]
Next, a method of assembling the oil ring 40 according to the embodiment to the piston 20 will be described. To assemble the oil ring 40 to the piston 20, first, the spacer expander 2 having the linear member 5 fitted in the expander groove 4 is mounted in the ring groove 30 of the piston 20, and then the pair of segments 1, 1 are mounted in the ring groove 30 so as to be spaced apart via the spacer expander 2. When mounting the spacer expander 2 in the ring groove 30, the spacer expander 2 is inserted into the ring groove 30 while widening the joint G1 of the expander main body 3, and the pair of joint ends of the expander main body 3 are inserted in the ring groove 30. The ring groove 30 is mounted by abutting the 3a and 3b. As described above, in the spacer expander 2, the state in which the linear member 5 is fitted in the expander groove 4 across the joint G1 is maintained, and the joint end 3b is the fitting portion of the linear member 5. It is slidable in the circumferential direction along 51 . Therefore, when the abutment G1 of the expander body 3 expands, the abutment end 3b moves along the fitting portion 51 and expands while being guided by the fitting portion 51. As shown in FIG. When the spacer expander 2 is mounted in the ring groove 30 and the joint G1 is closed, the joint end 3b moves along the fitting portion 51 and is guided by the fitting portion 51 to be closed. As a result, when the spacer expander 2 is assembled to the piston 20, the expander main body 3 is maintained in a posture in which the pair of abutment ends 3a and 3b face each other, and the pair of abutment ends 3a and 3b overlap each other. is prevented.

[Action/effect]
As described above, the spacer expander 2 according to the embodiment is formed in an annular shape along the circumferential direction of the oil ring 40, and the expander main body is formed in a wave shape that is continuous in the circumferential direction when viewed in the radial direction of the oil ring 40. 3, an expander groove 4 formed in the expander main body 3 so as to extend along the circumferential direction of the oil ring 40 across the gap G1, and an expander groove 4 formed in an arc along the circumferential direction of the oil ring 40. The fitting portion 51 is fitted in the expander groove 4 so as to straddle the abutment G1, thereby maintaining the expander main body 3 in a posture in which the pair of abutment ends 3a and 3b face each other. and a linear member 5 including a portion 51 .

According to the spacer expander 2 according to the embodiment, it is possible to prevent the pair of abutment ends 3a and 3b from overlapping each other in the radial and axial directions. As a result, it is possible to prevent difficulty in assembling the segment 1 in the operation of assembling the oil ring 40 to the piston 20 and prevent the oil ring 40 assembled to the piston 20 from failing to exhibit its function. Furthermore, since the axially wavy spacer expander has a narrow axial width and a narrow radial thickness, it is difficult to provide holes for inserting linear members. employs a structure in which the linear member 5 is fitted by providing a groove. As a result, it is possible to prevent the pair of abutment ends from overlapping each other, even though it is an axially wavy spacer expander. Further, the spacer expander 2 according to the embodiment employs a configuration in which the linear members 5 are fitted in the expander grooves 4 formed in the expander main body 3 and opened to the outside. As a result, unlike the technique of fixing the abutment ends with pins or the like, the expander main body 3 can be guided by the linear member 5 to be expanded or contracted in diameter. 20 can be easily attached and detached. Therefore, replacement of the oil ring 40 including the segment 1 and the spacer expander 2 is facilitated. As a result, the oil ring 40 can be used as a spare part (repair part).

Further, the expander grooves 4 of the spacer expander 2 according to the embodiment are arranged along the circumferential direction of the oil ring 40 by notches 37 provided in the outer ends E1 of the plurality of connecting pieces 33 to extend the expander grooves. It is formed on the outer peripheral surface S<b>1 of the main body 3 . The width w1 of the fitting portion 51 of the linear member 5 in the axial direction corresponds to the width b1 of the outer end portion E1 of the connecting piece 33 in the axial direction (in this example, the width b1 between the lower surface and the lower side of the upper support portion 312 in the axial direction). distance from the upper surface of the support portion 322). According to this, by making the width w1 of the fitting portion 51 in the axial direction smaller than the width b1 of the outer end portion E1 of the connecting piece 33 in the axial direction, the fitting portion 51 is positioned between the pair of segments 1, 1. can be fitted.

Furthermore, in the spacer expander 2 according to the embodiment, the curvature radius r2 of the arc at the inner peripheral end portion 512 of the fitting portion 51 of the linear member 5 in the free state is the same as that of the pair of abutment ends 3a and 3b in the free state. is less than the curvature radius R1 of the outermost periphery of the expander main body 3 in the state of being abutted against. Thereby, the spacer expander 2 can maintain the state in which the linear member 5 is fitted in the expander groove 4 across the gap G1. The curvature radius r2 of the linear member 5 in the free state is 0 to -10% of the curvature radius R1 of the expander main body 3 in the state where the pair of abutment ends 3a and 3b are butted against each other in the free state. It is preferably within the range, more preferably within the range of 0 to -5%. This makes it difficult for the linear member 5 to come off the expander groove 4 . However, the present invention is not limited to this.

Here, the length in the circumferential direction of the fitting portion 51 of the linear member 5 is 2 mm from one abutment end (abutment end on the side where the locking portion 52 is fixed) toward the other abutment end. It is preferable to set it as above. Also, the locking portion 52 is not an essential component of the present invention. In other words, the linear member according to the present invention does not have to have the engaging portion, and the entire linear member may be the fitting portion. In this case, the length of the fitting portion in the circumferential direction is preferably 1/2 or more, more preferably 2/3 or more, of the entire circumference of the expander main body. By doing so, the inner peripheral surface of the linear member (more specifically, the inner peripheral end portion) and the outer peripheral surface of the expander main body (more specifically, the bottom portion of the expander groove) are engaged with each other, thereby forming a linear member. It becomes difficult to remove the parts. Further, when the linear member does not have the engaging portion, both of the pair of abutment ends of the expander main body are slidable in the circumferential direction along the linear member, so that the abutment end is attached to the linear member. Since they are guided, the abutment ends are prevented from overlapping each other.

Also, in the present invention, one end of the linear member may be fixed to the expander main body by a method such as adhesion, welding, or brazing, instead of using the locking portion 52 described above. Alternatively, a burr formed on the linear member or the expander main body may be used to hook one end of the linear member to the expander main body by hooking the burr.

[Modification]
Modifications of the embodiment will be described below. In the following description, differences from the above-described oil ring 40 will be mainly described, and detailed description will be omitted by assigning the same reference numerals to the same configurations.

[Modification 1]
FIG. 8 is a partial cross-sectional view of an internal combustion engine 100A including an oil ring 40A according to Modification 1 of the embodiment. FIG. 8 shows a cross section perpendicular to the circumferential direction of the oil ring 40A. As shown in FIG. 8, the spacer expander 2A of the oil ring 40A according to Modification 1 differs from the spacer expander 2 in that expander grooves 4A are formed in the inner peripheral surface S2 of the expander main body 3A. do.

As shown in FIG. 8, in the spacer expander 2A, a notch 37 opening radially inward (inner peripheral side) is formed in the inner end E2, which is the radially inner end of the connecting piece 33 of the expander main body 3A. formed. The inner wall of the notch 37 is formed in an arcuate shape protruding radially outward. The cutouts 37 are provided in the plurality of connecting pieces 33 so as to be arranged along the circumferential direction. As a result, expander grooves 4A are formed on the inner peripheral surface S2 of the expander main body 3A, extending along the circumferential direction across the gap G1 and opening to the inner peripheral side. In this example, the expander groove 4A is formed in the center of the connecting piece 33 in the axial direction. good. A fitting portion 51 of the linear member 5A is fitted in the expander groove 4A so as to straddle the gap G1. The axial width w1 of the fitting portion 51 of the linear member 5A corresponds to the axial width b2 of the inner end portion E2 of the connecting piece 33, that is, the lower surface of the upper ear portion 311 and the upper surface of the lower ear portion 321 in the axial direction. less than the distance from

Here, in Modification 1, in the free state, the expander in which the curvature radius r1 of the arc at the outer peripheral end portion 511 of the fitting portion 51 of the linear member 5A abuts the pair of abutment ends 3a and 3b. The dimensions of R2 and r1 are set so that the radius of curvature of the innermost circumference of the main body 3A (the distance from the central axis of the expander main body 3A to the inner peripheral surface S2) R2 or more. As a result, the linear member 5A can be fitted into the expander groove 4A. Here, when the dimension of r1 exceeds the dimension of R2, the diameter of the linear member 5A is reduced by fitting the linear member 5A into the expander groove 4A. A self-tension occurs that tends to break. As a result, in the spacer expander 2A in which the linear member 5A is fitted in the expander groove 4A, the outer peripheral end portion 511 of the linear member 5A presses the expander main body 3A radially outward. As a result, the state in which the linear member 5A is fitted in the expander groove 4A across the gap G1 is maintained.

FIG. 9 is a top view of part of the spacer expander 2A according to Modification 1 of the embodiment. A locking portion 52A of the linear member 5A according to Modification 1 is connected to one end portion of the fitting portion 51 and is bent so as to protrude radially outward. The locking portion 52A includes a first bent portion 521A extending radially outward from one end portion of the fitting portion 51, and a second bent portion 522A bent from the tip of the first bent portion 521A and extending radially inward. include. The second bent portion 522A includes one end of the linear member 5A. As shown in FIG. 9, in the spacer expander 2A, the first bent portion 521A connected to the end portion of the fitting portion 51 extends from the inner peripheral surface S2 side of the expander main body 3A through the gap G2 to the outer periphery on the opposite side. The second bent portion 522A extending to the surface S1 side and connected to the first bent portion 521A is folded back and extends from the outer peripheral surface S1 side to the inner peripheral surface S2 side on the opposite side through the adjacent gap G2. . As a result, the connecting piece 33 is sandwiched from both sides in the circumferential direction by the first bent portion 521A and the second bent portion 522A. Further, the tip of the second bent portion 522A abuts on the connecting piece 33 and does not protrude toward the inner peripheral side of the expander main body 3A. Here, FIG. 10 is a sectional view showing a BB section of FIG. As shown in FIG. 10, a notch 38 into which the locking portion 52A is fitted is formed in the outer end portion E1 of the connecting piece 33 corresponding to the bent portion of the locking portion 52A. This prevents the linear member 5A from protruding to the outer peripheral side of the expander main body 3A. In the spacer expander 2A, the fitting portion 51 is fitted into the expander groove 4A formed on the inner peripheral surface S2 side of the expander main body 3A, and the engaging portion 52A is formed on the outer peripheral surface S1 side of the expander main body 3A. The linear member 5A is restricted from moving relative to the expander main body 3A in the radial direction by fitting into the notch 38 formed in the above. In the spacer expander 2A, the connecting piece 33 on the side of the abutment end 3a is sandwiched between the first bent portion 521A and the second bent portion 522A from both sides in the circumferential direction. Since the distal end of the second bent portion 522A abuts on 33, relative movement in the circumferential direction with respect to the abutment end portion 3a of the linear member 5A is restricted. As a result, one end (locking portion 52A) of the linear member 5A is locked on the joint end portion 3a side of the expander main body 3A, thereby preventing the linear member 5A from coming off the expander main body 3A. On the other hand, the other end of the linear member 5A is not locked on the side of the abutment end 3b of the expander main body 3A. It can slide in any direction.

According to the spacer expander 2A according to Modification 1, similarly to the spacer expander 2 described above, the pair of abutment ends 3a and 3b are maintained in a posture in which the expander main body 3A faces each other. It is possible to prevent the portions 3a and 3b from overlapping each other in the radial direction and the axial direction. Further, the expander grooves 4A of the spacer expander 2A according to Modification 1 are extracted by notches 37 provided in the inner end portions E2 of the plurality of connecting pieces 33 so as to be arranged along the circumferential direction of the oil ring 40. It is formed on the inner peripheral surface S2 of the panda body 3A. The width w1 of the fitting portion 51 of the linear member 5A in the axial direction is the width b2 of the inner end E2 of the connecting piece 33 in the axial direction (in this example, the width b2 between the lower surface and the lower ear of the upper ear portion 311 in the axial direction). distance from the upper surface of the portion 321). According to this, by making the width w1 of the fitting portion 51 in the axial direction smaller than the width b2 of the inner end portion E2 of the connecting piece 33 in the axial direction, the fitting portion 51 is made closer to the inner peripheral surface S2 of the expander main body 3A. can be fitted to the Furthermore, in the spacer expander 2A according to Modification 1, the curvature radius r1 of the arc at the outer peripheral end portion 511 of the fitting portion 51 of the linear member 5A in the free state is the same as that of the pair of abutment ends 3a and 3b in the free state. is greater than or equal to the radius of curvature R2 of the innermost periphery of the expander main body 3A in the state of being abutted against. Thereby, it is possible to maintain the state in which the linear member 5A is fitted in the expander groove 4A across the gap G1. The curvature radius r1 of the linear member 5A in the free state is in the range of 0 to +10% with respect to the curvature radius R2 of the expander main body 3 in the state where the pair of abutment ends 3a and 3b are butted against each other in the free state. preferably within the range of 0 to +5%. This makes it difficult for the linear member 5A to come off the expander groove 4A. However, the present invention is not limited to this.

[Modification 2]
FIG. 11 is a partial cross-sectional view of an internal combustion engine 100B provided with an oil ring 40B according to Modification 2 of the embodiment. FIG. 11 shows a cross section perpendicular to the circumferential direction of the oil ring 40B. As shown in FIG. 11, the spacer expander 2B of the oil ring 40B according to Modification 2 differs from the spacer expander 2 in that expander grooves 4B are formed in the upper surface S3 of the expander main body 3B.

As shown in FIG. 11, in the spacer expander 2B, a notch 37 opening upward (combustion chamber side) is formed in the upper piece 31 of the expander main body 3B. More specifically, the notch 37 is formed in the upper base portion 310 between the upper ear portion 311 and the upper support portion 312 of the upper piece 31 . The inner wall of the notch 37 is formed in an arcuate shape protruding toward the crank chamber. The notches 37 are provided in the plurality of upper pieces 31 so as to be arranged along the circumferential direction. As a result, expander grooves 4B are formed on the upper surface S3 of the expander main body 3B, extending in the circumferential direction across the gap G1 and opening upward. In this example, the expander groove 4B is formed in the center of the upper base portion 310 in the radial direction, but the position of the expander groove 4B in the radial direction may be closer to the outer peripheral side or the inner peripheral side. A fitting portion 51 of the linear member 5B is fitted in the expander groove 4B so as to straddle the gap G1. As shown in FIG. 11, the radial thickness t1 of the fitting portion 51 of the linear member 5B is greater than the radial thickness of the expander body 3 (the radial distance between the outermost circumference and the innermost circumference). is also small. More specifically, the thickness t1 is smaller than the radial thickness a1 of the upper base portion 310 of the upper piece 31 (in this example, the radial distance between the upper ear portion 311 and the upper support portion 312). A linear member 5</b>B according to Modification 2 is locked to the expander body 3</b>B by locking portions 52 , like the linear member 5 .

According to the spacer expander 2B according to Modification 2, similarly to the spacer expander 2 described above, the pair of abutment ends 3a and 3b are maintained in a posture in which the expander main body 3B faces each other. It is possible to prevent the portions 3a and 3b from overlapping each other in the radial direction and the axial direction. Further, in the spacer expander 2B according to Modification 2, the thickness t1 in the radial direction of the fitting portion 51 is the thickness a1 in the radial direction of the upper base portion 310 (in this example, the upper ear portion 311 and the upper support portion 312). ), the fitting portion 51 can be fitted to the upper base portion 310 .

Here, in the spacer expander 2B according to Modification Example 2, the radius of curvature r1 of the arc at the outer peripheral end portion 511 of the fitting portion 51 of the linear member 5B in the free state is the same as the pair of abutment ends 3a and 3b in the free state. +10% or less of the curvature radius R1 of the outermost periphery of the expander main body 3B in the state where the In the free state, r2 is preferably -10% or more of the radius of curvature R2 of the innermost periphery of the expander body 3B with the pair of abutment ends 3a and 3b abutting against each other. This makes it difficult for the linear member 5B to come off the expander groove 4B, and reduces the resistance when the expander main body 3B is contracted or expanded. Note that r1 may be equal to R1 or less than or equal to R1, and r2 may be equal to or greater than R2. Here, when the radius of curvature r1 of the arc at the outer peripheral end portion 511 of the linear member 5B exceeds the radius of curvature R1 of the outermost periphery of the expander main body 3B, that is, when r1 is greater than R1 and +10% or less of R1 Since the diameter of the linear member 5B is reduced by fitting the linear member 5B into the expander groove 4B, self-tension is generated in the linear member, and the outer peripheral end portion 511 of the linear member 5B is expanded. The expander main body 3B is pressed radially outward. Similarly, when the radius of curvature r2 of the arc at the inner peripheral end portion 512 of the linear member 5B is less than the radius of curvature R2 of the innermost periphery of the expander main body 3B, that is, r2 is -10% or more of R2 and R2 If the linear member 5B is fitted into the expander groove 4B, the diameter of the linear member 5B is expanded so that self-tension is generated in the linear member 5B, and the inner circumference of the linear member 5B is The end portion 512 presses the expander main body 3B radially inward. As a result, the state in which the linear member 5B is fitted in the expander groove 4B across the gap G1 is maintained. However, the above conditions of R1, R2, r1, and r2 do not limit the present invention.

[Modification 3]
FIG. 12 is a partial cross-sectional view of an internal combustion engine 100C including an oil ring 40C according to Modification 2 of the embodiment. FIG. 12 shows a cross section perpendicular to the circumferential direction of the oil ring 40C. As shown in FIG. 12, a spacer expander 2C of an oil ring 40C according to Modification 3 differs from the spacer expander 2 in that expander grooves 4C are formed in the lower surface S4 of the expander main body 3C.

As shown in FIG. 12, in the spacer expander 2C, the lower piece 32 of the expander main body 3C is formed with a notch 37 opening downward (toward the crank chamber). More specifically, the notch 37 is formed in the lower base portion 320 between the lower ear portion 321 and the lower support portion 322 of the lower piece 32 . The inner wall of the notch 37 is formed in an arcuate shape protruding toward the combustion chamber. The notches 37 are provided in the plurality of lower pieces 32 so as to be arranged along the circumferential direction. As a result, expander grooves 4C are formed in the lower surface S4 of the expander main body 3C, extending in the circumferential direction across the gap G1 and opening downward. In this example, the expander groove 4C is formed in the center of the lower base portion 320 in the radial direction, but the position of the expander groove 4C in the radial direction may be closer to the outer peripheral side or the inner peripheral side. . A fitting portion 51 of the linear member 5C is fitted in the expander groove 4C so as to straddle the gap G1. As shown in FIG. 12, the radial thickness t1 of the fitting portion 51 of the linear member 5C is greater than the radial thickness of the expander body 3 (the radial distance between the outermost circumference and the innermost circumference). is also small. More specifically, the thickness t1 is smaller than the radial thickness a2 of the lower base portion 320 (in this example, the radial distance between the lower ear portion 321 and the lower support portion 322). 5 C of linear members which concern on the modification 3 are latched by 3 C of expander main bodies by the latching|locking part 52 like the linear member 5. FIG.

According to the spacer expander 2C according to Modification 3, similarly to the spacer expander 2 described above, the pair of abutment ends 3a and 3b are maintained in a posture in which the expander main body 3C faces each other. It is possible to prevent the portions 3a and 3b from overlapping each other in the radial direction and the axial direction. Further, in the spacer expander 2C according to the third modification, the thickness t1 in the radial direction of the fitting portion 51 is the thickness a2 in the radial direction of the lower base portion 320 (in this example, the lower ear portion 321 and the lower support portion). 322 in the radial direction), the fitting portion 51 can be fitted to the lower base portion 320 .

Here, in the spacer expander 2C according to Modification 3, as in Modification 2, the curvature radius r1 of the arc at the outer peripheral end portion 511 of the fitting portion 51 of the linear member 5C in the free state is a pair of +10% or less of the curvature radius R1 of the outermost periphery of the expander main body 3C in the state where the abutment ends 3a and 3b are butted against each other, and the inner peripheral end of the fitting portion 51 of the linear member 5C in the free state In the free state, the radius of curvature r2 of the arc at the portion 512 may be -10% or more with respect to the radius of curvature R2 of the innermost periphery of the expander main body 3C when the pair of abutment ends 3a and 3b are in contact with each other. preferable. This makes it difficult for the linear member 5C to come off the expander groove 4C, and reduces the resistance when the diameter of the expander main body 3C is contracted or expanded. Note that r1 may be equal to R1 or less than or equal to R1, and r2 may be equal to or greater than R2. Here, when r1 exceeds R1 (that is, when r1 is greater than R1 and +10% or less of R1) or when r2 is less than R2 (that is, when r2 is -10% or more of R2 and less than R2 case), since the linear member 5C is self-tensioned, the state in which the linear member 5C is fitted in the expander groove 4C across the gap G1 is maintained. However, the above conditions of R1, R2, r1, and r2 do not limit the present invention.

[Modification 4]
FIG. 13 is a partial cross-sectional view of an internal combustion engine 100D including an oil ring 40D according to Modification 4 of the embodiment. FIG. 13 shows a cross section perpendicular to the circumferential direction of the oil ring 40D. As shown in FIG. 13, the spacer expander 2D of the oil ring 40D according to Modification 4 differs from the spacer expander 2 in that the expander main body 3D does not have the upper support portion 312 and the lower support portion 322. . As shown in FIG. 13, in Modification 4, the axial width b1 of the outer end E1 of the connecting piece 33 is equal to the axial distance between the lower surface of the upper base portion 310 and the upper surface of the lower base portion 320. . In the spacer expander 4D according to Modification 4, the width w1 of the fitting portion 51 of the linear member 5D in the axial direction is smaller than the width b1 of the outer end portion E1 of the connecting piece 33 in the axial direction. The fitting portion 51 can be fitted to the outer peripheral surface S1 of the expander main body 3D.

[Modification 5]
FIG. 14 is a partial cross-sectional view of an internal combustion engine 100E including an oil ring 40E according to Modification 5 of the embodiment. FIG. 14 shows a cross section perpendicular to the circumferential direction of the oil ring 40E. As shown in FIG. 14, the spacer expander 2E of the oil ring 40E according to Modification 5 is similar to the spacer expander according to Modification 1 in that the expander main body 3E does not have the upper support portion 312 and the lower support portion 322. It differs from Panda 2A. In the spacer expander 4E according to Modification 5, the width w1 of the fitting portion 51 of the linear member 5E in the axial direction is smaller than the width b2 of the inner end portion E2 of the connecting piece 33 in the axial direction. The fitting portion 51 can be fitted to the inner peripheral surface S2 of the expander main body 3E.

[Modification 6]
FIG. 15 is a partial cross-sectional view of an internal combustion engine 100F including an oil ring 40F according to Modification 6 of the embodiment. FIG. 15 shows a cross section perpendicular to the circumferential direction of the oil ring 40F. As shown in FIG. 15, the spacer expander 2F of the oil ring 40F according to Modification 6 is similar to the spacer expander according to Modification 2 in that the expander main body 3F does not have the upper support portion 312 and the lower support portion 322. It differs from Panda 2B. In the sixth modification, the radial thickness a1 of the upper base portion 310 is equal to the radial distance between the upper ear portion 311 and the outer end portion E1 of the connecting piece 33 . In the spacer expander 4F according to Modification 6, the radial thickness t1 of the fitting portion 51 of the linear member 5F is made smaller than the radial thickness a1 of the upper base portion 310. The portion 51 can be fitted to the upper base portion 310 .

[Modification 7]
FIG. 16 is a partial cross-sectional view of an internal combustion engine 100G provided with an oil ring 40G according to Modification 7 of the embodiment. FIG. 16 shows a cross section perpendicular to the circumferential direction of the oil ring 40G. As shown in FIG. 16, the spacer expander 2G of the oil ring 40G according to Modification 7 is similar to the spacer expander according to Modification 3 in that the expander main body 3G does not have the upper support portion 312 and the lower support portion 322. It is different from Panda 2C. In Modified Example 7, the radial thickness a2 of the lower base portion 320 is equal to the radial distance between the lower ear portion 321 and the outer end portion E1 of the connecting piece 33 . In a spacer expander 4G according to Modification 7, the radial thickness t1 of the fitting portion 51 of the linear member 5G is made smaller than the radial thickness a2 of the lower base portion 320. The mounting portion 51 can be fitted to the lower base portion 320 .

[Modification 8]
Next, a spacer expander used for an oil ring according to Modification 8 of the embodiment will be described. FIG. 17 is a top view of part of a spacer expander 2H according to Modification 8 of the embodiment. FIG. 18 is a top view (viewed from above in the axial direction) of a linear member 5H according to Modification 8 of the embodiment.

As shown in FIG. 18, the linear member 5H used in the spacer expander 2H is similar to the linear member 5 described in FIG. differ from The locking portion 53 is formed by bending the end portion of the linear member 5H. As shown in FIG. 18 , the locking portion 53 includes a first bent portion 531 extending radially inward from an end portion of the fitting portion 51 and a circumferentially outward (fitting portion) bent from the tip of the first bent portion 531 . and a second bent portion 532 extending in a direction opposite to the portion 51 . The linear member 5H is formed in a substantially U-shape as a whole by the fitting portion 51 and the pair of locking portions 53,53. Hereinafter, when the pair of locking portions 53, 53 of the linear member 5H are separately described, the locking portion 53 connected to one end of the fitting portion 51 is referred to as a first locking portion 53a. The engaging portion 53 connected to the other end portion of the mounting portion 51 is referred to as a second engaging portion 53b. In this example, the first locking portion 53a is engaged with the connecting piece 33 on the side of the abutment end 3a, and the first locking portion 53b is engaged with the connecting piece 33 on the side of the abutment end 3b.

As shown in FIG. 17, the expander main body 3H of the spacer expander 2H has notches 38 provided at the inner ends E2 of two connecting pieces 38 located on opposite sides of the joint G1. The expander body 3 is the same as the expander main body 3 described with reference to FIGS. That is, the expander grooves 4 are formed in the outer peripheral surface S1 of the expander main body 3 by the plurality of cutouts 37 provided in the outer end portions E1 of the plurality of connecting pieces 33 . As shown in FIG. 17, the expander main body 3H has a notch 38 for fitting the second bent portion 532 of the first locking portion 53a and the second bent portion 532 of the second locking portion 53b. A notch 38 for fitting is formed. A pair of notches 38, 38 are formed at the inner end E2 of the connecting piece 33 on the side of the abutment end 3a and the inner end E2 of the connecting piece 33 on the side of the abutment end 3b.

As shown in FIG. 17, in the spacer expander 2H, the first bent portions 531 of the pair of locking portions 53, 53 extend from the outer peripheral side to the inner peripheral side of the expander main body 3H through the gap G2 to form the second bent portions. The portion 532 engages the inner end E2 of the connecting piece 33 .

In Modified Example 8, the linear member 5 is fitted into the expander body 3H after the expander body 3H is mounted in the ring groove 30, so that the pair of abutment ends 3a and 3b are overlapped by the fitting portion 51. prevented. As a result, the pair of segments 1, 1 can be assembled to the spacer expander 2H in a state in which the pair of abutment ends 3a, 3b of the spacer expander 2H are prevented from overlapping each other.

In order to fit the linear member 5H to the expander main body 3H, the locking portion 53 is contracted inward in the circumferential direction (toward the fitting portion 51) against the elastic force of the linear member 5H, and then fitted. The portion 51 is fitted into the expander groove 4 , the locking portion 53 is inserted between the connecting pieces 33 , and the second bent portion 532 is fitted into the notch 38 to engage with the connecting piece 33 . When the linear member 5H is fitted in the expander main body 3H, the elasticity of the linear member 5H causes the locking portion 53 to generate a restoring force that tends to protrude outward in the circumferential direction. It will be in a state of being pressed against the piece 33 (a stretched state). Therefore, the state in which the second bent portion 532 is engaged with the connecting piece 33 is maintained.

In the spacer expander 2H, the fitting portions 51 of the linear members 5H are fitted into the expander grooves 4 formed on the outer peripheral surface S1 side of the expander main body 3H. are engaged with the inner end E2 of the connecting piece 33 of the expander main body 3H, the relative movement of the linear member 5H with respect to the expander main body 3H in the radial direction and the circumferential direction is restricted. ing. Thereby, the linear member 5H is locked to the expander main body 3H, and the linear member 5H is prevented from coming off from the expander main body 3H. In Modified Example 8, by providing the locking portions 53 at both end portions of the fitting portion 51, the linear member 5H can be securely attached to the expander main body 3H as compared with the case where the locking portions 53 are provided only at one end portion. You can keep it fitted. Note that the shape of the locking portion 53 is not limited to the shape shown in FIG. 17 . For example, the locking portion 53 may have a shape in which the second bent portion 532 is bent from the tip of the first bent portion 531 and extends radially outward, similar to the locking portion 52 shown in FIG. Further, the linear member 5H may protrude toward the inner peripheral side of the expander main body 3H as long as it does not interfere with (contact with) the inner wall of the ring groove 30, and the notch 38 is not formed in the expander main body 3H. It's good.

<Others>
Although the preferred embodiments of the present invention have been described above, the various forms described above can be combined as much as possible.

100, 100A, 100B, 100C, 100D, 100E, 100F, 100G: internal combustion engine 10: cylinder 20: piston 30: ring groove 40, 40A, 40B, 40C, 40D, 40E, 40F, 40G: oil ring 1: segment 2 , 2A, 2B, 2C, 2D, 2E, 2F, 2G, 2H: spacer expanders 3, 3A, 3B, 3C, 3D, 3E, 3F, 3G, 3H: expander bodies 4, 4A, 4B, 4C, 4D , 4E, 4F, 4G: expander grooves 5, 5A, 5B, 5C, 5D, 5E, 5F, 5G, 5H: linear members

Claims (11)

1. A spacer expander provided between a pair of segments spaced apart in the axial direction of the oil ring in an oil ring assembled to a piston in an internal combustion engine,
   An expander body that is annularly formed along the circumferential direction of the oil ring and biases the pair of segments outward in the radial direction of the oil ring, the expander main body comprising a pair of abutments that face each other to form an abutment. an expander body including end portions and formed in a wave shape that is continuous in the circumferential direction when viewed in the radial direction of the oil ring;
   an expander groove formed in the expander body so as to extend along the circumferential direction of the oil ring across the gap;
   a linear member including a fitting portion formed in an arc shape along the circumferential direction of the oil ring, the fitting portion being fitted in the expander groove so as to straddle the gap. ,
   spacer expander.
2. The expander main body is
   a plurality of upper pieces arranged at intervals along the circumferential direction of the oil ring;
   a plurality of lower pieces provided so as to be positioned closer to the crank chamber in the internal combustion engine than the plurality of upper pieces in the axial direction of the oil ring when the oil ring is assembled to the piston, a plurality of lower pieces arranged so that each of the lower pieces is alternately arranged with each of the upper pieces in the circumferential direction of the oil ring;
   a plurality of connecting pieces that connect the upper piece and the lower piece that are adjacent in the circumferential direction of the oil ring,
   The upper piece includes an upper base portion and an inner side of the upper base portion in a radial direction of the oil ring. an upper ear that presses radially outwardly of the ring;
   The lower piece is formed upright inside the lower base portion and the lower base portion in the radial direction of the oil ring, and is the lower segment provided on the crank chamber side of the internal combustion engine among the pair of segments. a lower ear portion that presses radially outward of the oil ring,
   A spacer expander according to claim 1.
3. The expander grooves are arranged along the circumferential direction of the oil ring by a plurality of notches provided at the outer end of the plurality of connecting pieces, which is the radially outer end of the oil ring. formed on the outer peripheral surface of the expander main body,
   The width of the fitting portion in the axial direction of the oil ring is smaller than the width of the outer end portion of the connecting piece in the axial direction,
   A spacer expander according to claim 2.
4. The expander grooves are arranged along the circumferential direction of the oil ring by a plurality of notches provided in the inner end portion of the plurality of connecting pieces, which is the radially inner end portion of the oil ring, formed on the inner peripheral surface of the expander main body,
   The width of the fitting portion in the axial direction of the oil ring is smaller than the width of the inner end portion of the connecting piece in the axial direction,
   A spacer expander according to claim 2.
5. The expander groove is formed on the outer peripheral surface of the expander main body,
   In a free state before the oil ring is assembled to the piston, the radius of curvature of the arc at the inner peripheral end of the fitting portion is the maximum of the expander main body with the pair of abutment ends abutted against each other. is less than or equal to the radius of curvature of the outer circumference,
   A spacer expander according to any one of claims 1 to 3.
6. The expander groove is formed on the inner peripheral surface of the expander main body,
   In a free state before the oil ring is assembled to the piston, the radius of curvature of the arc at the outer peripheral end of the fitting portion is the innermost of the expander body with the pair of abutment ends abutted against each other. is greater than or equal to the radius of curvature of the circumference,
   5. A spacer expander according to any one of claims 1, 2 or 4.
7. The expander grooves are formed by a plurality of notches provided in the upper base portion of the plurality of upper pieces so as to be arranged along the circumferential direction of the oil ring,
   The thickness of the fitting portion in the radial direction of the oil ring is smaller than the thickness of the upper base portion in the radial direction,
   A spacer expander according to claim 2.
8. The expander groove is formed by a plurality of notches provided in the lower base portion of the plurality of lower pieces so as to be arranged along the circumferential direction of the oil ring,
   The thickness of the fitting portion in the radial direction of the oil ring is smaller than the thickness of the lower base portion in the radial direction,
   A spacer expander according to claim 2.
9. The expander groove is formed on one of both end surfaces of the expander main body in the axial direction of the oil ring,
   In a free state before the oil ring is assembled to the piston, the radius of curvature of the arc at the outer peripheral end of the fitting portion is the outermost periphery of the expander main body with the pair of abutment ends abutted against each other. and the curvature radius of the arc at the inner peripheral end of the fitting portion is the innermost of the expander body in a state where the pair of abutment ends are butted against each other -10% or more of the radius of curvature of the circumference,
   A spacer expander according to claim 1 or 2.
10. The expander groove is formed on the outer peripheral surface of the expander main body,
    The linear member further includes locking portions provided at both ends of the fitting portion,
    The engaging portion includes a first bent portion that is bent from an end portion of the fitting portion and extends from the outer peripheral side to the inner peripheral side of the expander main body through between the connecting pieces that are adjacent in the circumferential direction; a second bent portion that bends from the tip of the first bent portion and engages an inner end that is a radially inner end of the oil ring in the connecting piece,
    A spacer expander according to claim 2.
11. An oil ring assembled to a piston in an internal combustion engine,
    A pair of segments spaced apart in the axial direction of the oil ring, and a spacer expander provided between the pair of segments,
    The spacer expander is
    An expander body that is annularly formed along the circumferential direction of the oil ring and biases the pair of segments outward in the radial direction of the oil ring, the expander main body comprising a pair of abutments that face each other to form an abutment. an expander body including end portions and formed in a wave shape that is continuous in the circumferential direction when viewed in the radial direction of the oil ring;
    an expander groove formed in the expander body so as to extend along the circumferential direction of the oil ring across the gap;
    a linear member including a fitting portion formed in an arc shape along the circumferential direction of the oil ring, the fitting portion being fitted in the expander groove so as to straddle the gap. ,
    oil ring.

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