Spacer dilator and oil ring

Abstract

The spacer expansion device is provided with: an expander main body formed in a ring shape along the circumference of an oil ring, which exerts a force on a pair of scrapers to the outside in the radial direction of the oil ring, the expander main body including a pair of joint end portions formed by being opposed to each other to form a joint, and 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 main body in a manner extending across the joint and along the circumference of the oil ring; and a linear member including an embedded portion formed in a circular arc shape along the circumference of the oil ring, and embedded in the expander groove in a manner crossing the joint.

Description

Technical Field

[0001] The present invention relates to a spacer expander and an oil ring composed of a scraper and a spacer expander. Background Technology

[0002] The internal combustion engines in ordinary automobiles are constructed by fitting piston rings, including compression rings and oil rings, into the ring grooves of the piston. Axially, the compression ring is located on the combustion chamber side, and the oil ring is located on the crankcase side. The compression ring and oil ring function by sliding against the cylinder wall. The oil ring has the following functions: a sealing function to prevent oil from flowing out of the combustion chamber side (oil rise) by scraping excess oil (lubricating oil) adhering to the cylinder wall towards the crankcase side; and a function to prevent piston seizure during engine operation by adjusting the oil quantity to properly maintain the lubricating oil film on the cylinder wall. The compression ring has the following functions: a sealing function to prevent combustion gases from flowing out of the combustion chamber side to the crankcase side (air leakage) by maintaining an airtight seal; and a sealing function to prevent oil rise by scraping off excess oil that the oil ring has not completely scraped off.

[0003] Here, as an oil ring, a three-piece combined oil ring is widely used, consisting of a pair of scrapers (also called side rails) that slide on the inner wall of the cylinder and a spacer that applies force to the pair of scrapers on the inner wall of the cylinder. Regarding such a combined oil ring, a combined oil ring having a spacer formed by multiple wavy periodic units connected circumferentially in an axially displaced manner is disclosed (for example, Patent Document 1). When installing the three-piece combined oil ring onto the piston, the spacer is first installed into the ring groove, and then the scrapers are installed into the ring groove. When installing the spacer into the ring groove, the spacer is placed into the ring groove while widening the joint of the spacer, and is installed into the ring groove by abutting the joint ends of the spacer within the ring groove.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2013 / 069349

[0007] Patent Document 2: Japanese Utility Model Publication No. 56-85048

[0008] Patent Document 3: Japanese Utility Model Application Publication No. 1-25448

[0009] Patent Document 4: Japanese Utility Model Application Publication No. 3-38456

[0010] Patent Document 5: Japanese Utility Model Publication No. 60-18242 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] When the conventional axially wavy (a continuous wavy shape in the circumferential direction when viewed radially from the oil ring) spacer is fitted into the piston ring groove, the joint ends may overlap each other radially or axially on the oil ring. If this occurs, it may be difficult to install the scraper. Furthermore, even if the scraper can be installed, it may be impossible to apply appropriate force to it, thus preventing it from functioning as an oil ring. For example, the scraper may come into strong contact with the upper and lower surfaces of the ring groove, preventing it from extending towards the cylinder wall.

[0013] The present invention was made in view of the above-mentioned problems, and its object is to provide a technique for preventing the joint ends of the spacer expanders from overlapping each other in an oil ring having an axially wavy spacer expander.

[0014] Solution for solving the problem

[0015] To solve the above problems, the present invention employs the following configuration. Specifically, the present invention is a spacer expander disposed in the oil ring of a piston mounted in an internal combustion engine, between a pair of blades axially separated from each other in the oil ring. The spacer expander comprises: an expander body formed in an annular shape along the circumference of the oil ring, which applies force to the pair of blades radially outward from the oil ring; the expander body including a pair of joint ends that form a joint by opposing each other, and formed in a wavy shape continuously in the circumferential direction when viewed radially from the oil ring; an expander groove formed in the expander body such that it crosses the joint and extends circumferentially along the oil ring; and a linear member including an insert portion formed in an arc shape along the circumference of the oil ring and fitted into the expander groove such that it crosses the joint.

[0016] According to the present invention, the expander body is held in an opposing posture at one end of the joint by a linear member, thereby preventing the ends of the joint from overlapping each other radially and axially. This prevents difficulties in installing the scraper during the installation of the oil ring onto the piston, and prevents the oil ring installed on the piston from failing to function. Furthermore, the axial width and radial thickness of the axially wavy spacer expander are narrow, making it difficult to provide holes for inserting the linear member. However, in the present invention, a structure is adopted in which the inserting part is fitted into a groove provided in the expander body. Therefore, even with an axially wavy spacer expander, the ends of the joints can be prevented from overlapping each other.

[0017] Furthermore, in this invention, the expander body may also include: a plurality of upper plates arranged at intervals along the circumference of the oil ring; a plurality of lower plates arranged such that, when the oil ring is mounted on the piston, they are positioned axially on the crankcase side of the oil ring closer to the crankcase side in the internal combustion engine than the plurality of upper plates, each of the lower plates being arranged alternately with each of the upper plates in the circumferential direction of the oil ring; and a plurality of connecting plates connecting adjacent upper and lower plates in the circumferential direction of the oil ring. The upper plate includes: an upper base portion; and an upper ear portion, which stands upright on the inner side of the upper base portion formed radially on the oil ring, pressing the upper scraper of the pair of scrapers located on the combustion chamber side of the internal combustion engine toward the radial outer side of the oil ring. The lower plate includes: a lower base portion; and a lower ear portion, which stands upright on the inner side of the lower base portion formed radially on the oil ring, pressing the lower scraper of the pair of scrapers located on the crankcase side of the internal combustion engine toward the radial outer side of the oil ring.

[0018] Furthermore, in this invention, the expander groove may be formed on the outer peripheral surface of the expander body by a plurality of notches, the plurality of notches being arranged along the circumference of the oil ring at the outer ends of the radially outer ends of the oil ring in the plurality of connecting pieces, and the width of the axially mounted portion of the oil ring being smaller than the width of the axially mounted outer ends of the connecting pieces. This allows the mounted portion to be fitted onto the outer peripheral surface of the expander body.

[0019] Furthermore, in this invention, the expander groove may be formed on the inner circumferential surface of the expander body by a plurality of notches, the plurality of notches being arranged along the circumference of the oil ring at the inner end of the radially inner end of the oil ring among the plurality of connecting pieces, and the width of the axially mounted portion of the oil ring being smaller than the width of the inner end of the axially mounted connecting piece. This allows the mounted portion to be fitted into the inner circumferential surface of the expander body.

[0020] Furthermore, in this invention, the expander groove may be formed on the outer peripheral surface of the expander body. In the free state before the oil ring is installed on the piston, the radius of curvature of the arc at the inner peripheral end of the insert is less than the radius of curvature of the outermost periphery of the expander body after the joint ends are joined together. Accordingly, when the radius of curvature of the arc at the inner peripheral end of the insert is smaller than the radius of curvature of the outermost periphery of the expander body, the insert is enlarged by inserting it into the expander groove, thus generating a self-tension to reduce the diameter of the linear member. As a result, in the spacer expander, the inner peripheral end of the insert presses the expander body radially inward. Thus, the state in which the insert is inserted across the joint into the expander groove can be maintained.

[0021] Furthermore, in this invention, the expander groove may be formed on the inner circumferential surface of the expander body. In the free state before the oil ring is installed on the piston, the radius of curvature of the arc at the outer circumferential end of the insert is greater than or equal to the radius of curvature of the innermost circumference of the expander body after the joint ends are joined together. Accordingly, when the radius of curvature at the outer circumferential end of the insert is greater than the radius of curvature of the innermost circumference of the expander body, the insert is fitted into the expander groove, causing the insert to shrink in diameter, thus generating a self-tension to expand the diameter of the linear member. As a result, in the spacer expander, the outer circumferential end of the insert presses the expander body radially outward. This maintains the state in which the insert is fitted across the joint into the expander groove.

[0022] Furthermore, in this invention, the expander groove may be formed by multiple notches arranged circumferentially along the oil ring on the upper base portion of the plurality of upper plates, and the thickness of the insert portion in the radial direction of the oil ring is smaller than the thickness of the upper base portion in the radial direction. This allows the insert portion to be fitted into the combustion chamber side surface of the expander body.

[0023] Furthermore, in this invention, the expander groove may be formed by multiple notches arranged circumferentially along the oil ring on the lower base portion of the plurality of lower plates, wherein the thickness of the insert portion in the radial direction of the oil ring is smaller than the thickness of the lower base portion in the radial direction. This allows the insert portion to be fitted into the crankcase side surface of the expander body.

[0024] Furthermore, in this invention, the expander groove may be formed on either of the two end faces of the expander body along the axial direction of the oil ring. In the free state before the oil ring is installed on the piston, the radius of curvature of the arc at the outer peripheral end of the insert is within +10% of the radius of curvature of the outermost periphery of the expander body after the two seam ends are joined together, and the radius of curvature of the arc at the inner peripheral end of the insert is more than -10% of the radius of curvature of the innermost periphery of the expander body after the two seam ends are joined together. This makes it difficult for the insert to fall out of the expander groove, reducing the resistance during the reduction or expansion of the expander body's diameter. Furthermore, when the radius of curvature of the arc at the outer peripheral end of the insert is greater than the radius of curvature of the outermost periphery of the expander body, by inserting the insert into the expander groove and reducing the diameter of the insert, a self-tension is generated in the linear member, resulting in the outer peripheral end of the insert pressing the expander body radially outward. Thus, the linear member is maintained in a state where it is fitted across the seam into the expander groove. Similarly, when the radius of curvature of the arc at the inner circumference end of the fitting part is smaller than the radius of curvature of the innermost circumference of the expander body, the fitting part is enlarged by fitting the linear member into the expander groove. Therefore, self-tension is generated in the linear member, resulting in a state where the inner circumference end of the fitting part presses the expander body radially inward. Thus, the fitting part is maintained in a state where it is fitted across the seam into the expander groove.

[0025] Furthermore, in this invention, the expander groove may be formed on the outer peripheral surface of the expander body, and the linear member may further include locking portions provided at both ends of the fitting portion. Each locking portion includes: a first bending portion that bends from the end of the fitting portion and passes between adjacent connecting pieces in the circumferential direction, extending from the outer peripheral side to the inner peripheral side of the expander body; and a second bending portion that bends from the front end of the first bending portion and engages with the inner end of the connecting piece that serves as the radially inner end of the oil ring. Accordingly, by engaging the locking portions at both ends of the fitting portion with the expander body, the linear member can be maintained in the state of being fitted into the expander body.

[0026] Furthermore, the present invention can also be defined as an oil ring formed by combining a pair of scrapers and the aforementioned spacer expander. That is, the present invention can also be an oil ring comprising: a pair of scrapers disposed separately in the axial direction of the oil ring; and a spacer expander disposed between the pair of scrapers, the spacer expander comprising: an expander body formed in an annular shape along the circumference of the oil ring, applying force to the pair of scrapers radially outwards on the oil ring; the expander body including a pair of joint ends that form a joint by opposing each other, and formed in a wavy shape continuously in the circumferential direction when viewed radially from the oil ring; an expander groove formed in the expander body such that it crosses the joint and extends along the circumference of the oil ring; and a linear member including an insert portion formed in an arc shape along the circumference of the oil ring and fitted into the expander groove such that it crosses the joint.

[0027] Invention Effects

[0028] According to the present invention, in an oil ring having an axially wavy spacer expander, the joint ends of the spacer expanders can be prevented from overlapping each other. Attached Figure Description

[0029] Figure 1 This is a partial cross-sectional view of an internal combustion engine with an oil ring having an implementation method.

[0030] Figure 2 This is a perspective view of a portion of the expander body in the implementation method.

[0031] Figure 3 It is a cross-sectional view used to illustrate the outer and inner circumferences of the expander body.

[0032] Figure 4 This is a top view of the linear component in the embodiment.

[0033] Figure 5 This is a perspective view of a portion of the spacer in the implementation method.

[0034] Figure 6 This is a top view of a portion of the interval expander in the implementation method.

[0035] Figure 7 yes Figure 6 A-A sectional view.

[0036] Figure 8 This is a partial cross-sectional view of an internal combustion engine with an oil ring according to a modified example 1 of the embodiments.

[0037] Figure 9 This is a top view of a portion of the spacer in a variation of embodiment 1.

[0038] Figure 10 yes Figure 9 B-B sectional view.

[0039] Figure 11 This is a partial cross-sectional view of an internal combustion engine with an oil ring according to a modified example 2 of the implementation method.

[0040] Figure 12 This is a partial cross-sectional view of an internal combustion engine with an oil ring according to a modified example 3 of the implementation method.

[0041] Figure 13 This is a partial cross-sectional view of an internal combustion engine with an oil ring according to a modified example 4 of the implementation method.

[0042] Figure 14 This is a partial cross-sectional view of an internal combustion engine with an oil ring according to Modified Example 5 of the embodiments.

[0043] Figure 15 This is a partial cross-sectional view of an internal combustion engine with an oil ring according to a modified example 6 of the implementation method.

[0044] Figure 16 This is a partial cross-sectional view of an internal combustion engine with an oil ring according to a modified example 7 of the implementation method.

[0045] Figure 17 This is a top view of a portion of the spacer in variation 8 of the implementation method.

[0046] Figure 18 This is a top view of the linear member in variation 8 of the embodiment. Detailed Implementation

[0047] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the configurations described in the following embodiments are not intended to limit the technical scope of the invention.

[0048] [Overall Composition]

[0049] Figure 1 This is a partial cross-sectional view of an internal combustion engine 100 equipped with an oil ring 40 according to an embodiment. Figure 1 The diagram shows a cross-section orthogonal to the circumferential direction (circumferential direction) of the oil ring 40. For example... Figure 1 As shown, in the internal combustion engine 100, a piston clearance PC1 is formed by ensuring a predetermined separation distance 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. Furthermore, an annular groove 30 with a generally rectangular cross-section is formed on the outer peripheral surface 20a of the piston 20. The annular groove 30 has an upper wall 301 formed on the combustion chamber side, a lower wall 302 formed on the crankcase side and opposite to the upper wall 301, and a connecting wall 303 connecting the inner peripheral edges of the upper wall 301 and the lower wall 302 to each other. An oil ring 40 of this embodiment is mounted in this annular groove 30.

[0050] The oil ring 40 is a sliding component that slides on the inner wall surface 10a of the cylinder 10, accompanying the reciprocating motion of the piston 20. For example... Figure 1 As shown, the oil ring 40 is a so-called three-piece composite oil ring, comprising a pair of scrapers 1, 1 and a spacer expander 2. Furthermore, the spacer expander 2 comprises an expander body 3, an expander groove 4, and a linear member 5. The oil ring 40 is mounted to the piston 20 by fitting into the ring groove 30.

[0051] The following, such as Figure 1 As shown, the direction (axial direction) along the central axis of the oil ring 40 is defined as the "up and down direction". Furthermore, the combustion chamber side of the internal combustion engine 100 in the axial direction of the oil ring 40 is defined as... Figure 1 The upper side of the crankcase is defined as the "upper side", and its opposite side, namely the crankcase side, is defined as the "upper side". Figure 1 The lower side of the oil ring 40 is defined as "lower side". Furthermore, in the following description of the oil ring 40, unless otherwise specified, "circumferential" refers to the circumferential direction of the oil ring 40, "radial" refers to the radial direction of the oil ring 40, and "axial" refers to the axial direction of the oil ring 40. Additionally, in this specification, the following will be used... Figure 1 The state in which the oil ring is installed on the piston of the cylinder of an internal combustion engine is referred to as the "operational state". Furthermore, the state before the oil ring is installed on the piston is referred to as the "free state". More specifically, the free state refers to the state in which the oil ring is disassembled into its constituent parts—the scraper, the expander body, and the linear members—meaning that each of these constituent parts is not constrained by other elements. The components of the oil ring 40 will be described below.

[0052] [Scraper]

[0053] A pair of scraper blades 1, 1 are formed in a ring shape along the circumference of the oil ring 40 and are independently separated in the axial direction. In the embodiment of the oil ring 40, the pair of scraper blades 1, 1 are provided with the same shape. However, the shapes of the pair of scraper blades in this invention may be different. Hereinafter, when referring to the pair of scraper blades 1, 1 separately, the scraper blade 1 provided on the upper side (combustion chamber side) will be called the upper scraper blade 1U, and the scraper blade 1 provided on the lower side (crank chamber side) will be called the lower scraper blade 1L. When not distinguishing between them, they will simply be referred to as scraper blade 1. The material of scraper blade 1 is not particularly limited. Examples of materials for scraper blade 1 include SUS, SWRH, etc.

[0054] like Figure 1 As shown, the scraper 1 has an outer peripheral surface 11, an inner peripheral surface 12, an upper surface 13, and a lower surface 14. The upper surface 13 and the lower surface 14 define the axial width of the scraper 1. The upper scraper 1U is configured such that its upper surface 13 faces the upper wall 301 of the annular groove 30 in the use state. The lower scraper 1L is configured such that its lower surface 14 faces the lower wall 302 of the annular groove 30 in the use state.

[0055] [Gap Expander]

[0056] like Figure 1 As shown, the spacer expander 2 is disposed between a pair of scrapers 1, 1, and includes: an expander body 3 formed in a wave shape in the axial direction, an expander groove 4 formed in the expander body 3, and a linear member 5 embedded in the expander groove 4.

[0057] The expander body 3 is formed in an annular shape along the circumference 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 S3 is the surface disposed on the upper side (combustion chamber side) of the two axial end faces of the expander body 3. The lower surface S4 is the surface disposed on the lower side (crank chamber side) of the two axial end faces of the expander body 3. That is, the expander body 3 is configured such that, in the operating state, the upper surface S3 faces the upper scraper 1U and the lower surface S4 faces the lower scraper 1L. The material of the expander body 3 is not particularly limited. Examples of materials for the expander body 3 include SUS, etc.

[0058] Figure 2 This is a perspective view of a portion of the expander body 3 in the embodiment. (See attached image.) Figure 2 As shown, the expander body 3 is constructed by connecting multiple periodic units in a wave-like shape that are displaced axially in the circumferential direction. In other words, the expander body 3 is formed to be a continuous wave-like shape in the circumferential direction when viewed radially from the oil ring 40 (visually confirmed from the radially outer or inner side). Specifically, the expander body 3 includes: multiple upper plates 31 and lower plates 32, which are separated in the axial and circumferential directions and alternately arranged in the circumferential direction; and connecting plates 33, which connect adjacent upper plates 31 and lower plates 32 in the circumferential direction. The multiple upper plates 31 are arranged at intervals along the circumferential direction. The multiple lower plates 32 are positioned below the multiple upper plates 31 when the oil ring 40 is mounted on the piston 20 (that is, in the operating state). Furthermore, the multiple lower plates 32 are arranged such that each of the lower plates 32 is alternately arranged with each of the upper plates 31 in the circumferential direction. The upper plates 31 and lower plates 32 are orthogonal to the axial direction and separated from each other in the axial direction. Connecting piece 33 connects the circumferential ends of adjacent upper piece 31 and lower piece 32 to each other. Furthermore, as... Figure 2 As shown, the expander body 3 includes a pair of joint ends 3a and 3b that form a joint G1 by being opposed to each other. It should be noted that the construction of the expander body of the present invention is not limited to this, as long as it is formed in a wavy shape in the axial direction.

[0059] like Figure 1As shown, the upper plate 31 includes an upper base portion 310, an upper ear portion 311, and an upper support portion 312. The upper base portion 310 extends radially in a manner orthogonal to the axial direction. The upper ear portion 311 is formed upright on the inner side of the upper base portion 310 in the radial direction and protrudes upward relative to the upper base portion 310. Furthermore, in the use state, the upper ear portion 311 abuts against the inner peripheral surface 12 of the upper scraper 1U, thereby pressing the upper scraper 1U radially outward. 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 relative to the upper base portion 310. Furthermore, in the use state, the upper support portion 312 abuts against the lower surface 14 of the upper scraper 1U, thereby supporting the upper scraper 1U. In addition, a through hole 34 is formed at the root of the upper ear portion 311. It should be noted that the upper piece of the present invention may also not have the upper support portion 312.

[0060] like Figure 1 As shown, the lower blade 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 in a manner orthogonal to the axial direction. The lower ear portion 321 is formed upright on the inner side of the radially extending lower base portion 320, protruding downward relative to the lower base portion 320. Furthermore, in use, the lower ear portion 321 abuts against the inner circumferential surface 12 of the lower scraper 1L, thereby pressing the lower scraper 1L radially outward. The lower support portion 322 is formed upright on the outer side of the radially extending lower base portion 320, protruding downward relative to the lower base portion 320. Furthermore, in use, the lower support portion 322 abuts against the upper surface 13 of the lower scraper 1L, thereby supporting the lower scraper 1L. In addition, a through hole 34 is formed at the root of the lower ear portion 321. It should be noted that the lower piece of the present invention may also not have the lower support portion 322.

[0061] Here, Figure 1 Reference numeral E1 indicates the radially outer end (outer end) of the connecting piece 33, and reference numeral E2 indicates the radially inner end (inner end) of the connecting piece 33. Furthermore, the axial width of the outer end E1 is defined as b1, and the axial width of the inner end E2 is defined as b2. At this time, as... Figure 1 As shown, in this example, b1 is equal to the axial distance between the lower surface of the upper support portion 312 and the upper surface of the lower support portion 322, and b2 is equal to the axial distance between the lower surface of the upper ear portion 311 and the upper surface of the lower ear portion 321. Furthermore, the radial thickness of the upper base portion 310 is set as a1, and the radial thickness of the lower base portion 320 is set as a2. At this time, as... Figure 1 As shown, in this example, a1 is equal to the radial distance between the upper ear 311 and the upper support 312, and a2 is equal to the radial distance between the lower ear 321 and the lower support 322.

[0062] In addition, such as Figure 1 and Figure 2 As shown, a notch 37 opening radially outward (outer peripheral side) is formed at the outer end E1 of the connecting piece 33. The inner wall of the notch 37 is formed into a radially inward convex arc shape. However, the shape of the notch in this invention is not limited to an arc shape. The notches 37 are provided on a plurality of connecting pieces 33 in a circumferential arrangement. As a result, an expander groove 4 extending circumferentially and opening outward is formed on the outer peripheral surface S1 of the expander body 3. Figure 2 As shown, the expander groove 4 is formed by a plurality of notches 37 and extends across the seam G1. In this embodiment, the expander groove 4 is formed over the entire circumference of the expander body 3. However, the expander groove of the present invention is not limited thereto. The expander groove only needs to be formed on at least a portion of the expander body in a manner that spans the seam. It should be noted that in this example, the expander groove 4 is formed axially at the center of the connecting piece 33, but the axial position of the expander groove 4 can also be close to the side of the upper piece 31 or the side of the lower piece 32.

[0063] Figure 3 This is a cross-sectional view used to illustrate the outer and inner circumferences of the expander body 3. Figure 3 In the attached drawing, reference numeral CA3 denotes the central axis of the expander body 3. Here, the outer circumference of the expander body 3, that is, the radius of curvature of the outermost circumference of the expander body 3 (the distance from the central axis CA3 of the expander body 3 to the outer circumferential surface S1), is set as R1, and the inner circumference of the expander body 3, that is, the radius of curvature of the innermost circumference of the expander body 3 (the distance from the central axis CA3 of the expander body 3 to the inner circumferential surface S2), is set as R2. That is, R1 is the outer diameter of the expander body 3, and R2 is the inner diameter of the expander body 3.

[0064] Figure 4 This is a top view of the linear member 5 according to the embodiment (a view obtained from the upper axial side). The linear member 5 is a linear member formed by bending wire. The material of the linear member 5 is not particularly limited, but steel or resin can be used. Examples of materials for the linear member 5 include SUS, SWP, and resin. The linear member 5 includes an insert portion 51 and a locking portion 52. The insert portion 51 is formed in an arc shape along the circumference of the oil ring 40 and extends along the circumference of the oil ring 40. Figure 1As shown, the insert portion 51 has a circular cross-sectional shape to correspond to the cross-sectional shape of the expander groove 4 formed in the expander body 3. However, the present invention is not limited to this. The cross-sectional shape of the notch 37 does not necessarily have to be the same as the cross-sectional shape of the linear member 5. Furthermore, the cross-sectional shape of the linear member 5 may not be circular. In addition, the axial width w1 of the insert portion 51 is smaller than the axial width b1 of the outer end E1 of the connecting piece 33, 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.

[0065] like Figure 4 As shown, the locking portion 52 is connected to one end of the fitting portion 51 and is bent in a radially inward manner. The locking portion 52 includes a first bent portion 521 extending radially inward from one end of the fitting portion 51 and a second bent portion 522 bent from the front end of the first bent portion 521 and extending radially outward. The second bent portion 522 includes one end of the linear member 5.

[0066] Here, Figure 4 Reference numeral 511 indicates the outer peripheral end of the fitting portion 51 of the linear member 5. The outer peripheral end 511 is a part of the outer peripheral surface of the fitting portion 51 and is the outermost radially located portion of the fitting portion 51. Reference numeral 512 indicates the inner peripheral end of the fitting portion 51 of the linear member 5. The inner peripheral end 512 is a part of the inner peripheral surface of the fitting portion 51 and is the innermost radially located portion of the fitting portion 51. Reference numeral C5 indicates the center of the arc formed by the fitting portion 51. Here, the radius of curvature of the linear member 5 at the outer peripheral end 511 of the fitting portion 51 (the distance from the center C5 of the arc of the fitting portion 51 to the outer peripheral end 511) is set as r1, and the radius of curvature of the linear member 5 at the inner peripheral end 512 of the fitting portion 51 (the distance from the center C5 of the arc of the fitting portion 51 to the inner peripheral end 512) is set as r2.

[0067] Figure 5 This is a perspective view of a portion of the spacer expander 2 in the embodiment. Figure 5 The diagram illustrates the state where the ends 3a and 3b of a pair of seams are joined (butted) together. Figure 5 As shown, in the spacer expander 2, the insert portion 51 of the linear member 5 is fitted into the expander groove 4 of the expander body 3 in a manner that spans the joint G1. The fitting of the insert portion 51 and the expander groove 4 forms a clearance fitting state.

[0068] In this example, in the spacer expander 2, the dimensions R1 and r2 are set such that, in the free state, the radius of curvature r2 of the arc at the inner peripheral end 512 of the fitting portion 51 of the linear member 5 is less than the radius of curvature R1 of the outermost periphery of the expander body 3 after the joint ends 3a and 3b are joined together. This allows the linear member 5 to be fitted into the expander groove 4. Here, when the dimension r2 is smaller than the dimension R1, the linear member 5 expands in diameter by fitting it into the expander groove 4, thus generating a self-tension to reduce its diameter. Therefore, in the spacer expander 2 where the linear member 5 is fitted into the expander groove 4, the inner peripheral end 512 of the linear member 5 presses the expander body 3 radially inward. This maintains the state where the linear member 5 is fitted into the expander groove 4 across the joint G1. At this time, the radius of curvature r2 of the linear member 5 in the free state is preferably in the range of 0% to -10% relative to the radius of curvature R1 of the expander body 3 in the free state after the joint ends 3a and 3b are joined together. More preferably, it is in the range of 0% to -5%. As a result, the linear member 5 is less likely to fall off the expander groove 4.

[0069] Figure 6 This is a top view of a portion of the spacer expander 2 in the embodiment. (See attached image.) Figure 6 As shown, in the spacer expander 2, the locking part 52 of the linear member 5 engages with one of the multiple connecting pieces 33, thereby locking the linear member 5 to the expander body 3. In this example, the locking part 52 engages with the connecting piece 33 on the joint end 3a side of one pair of joint ends 3a, 3b separated by the joint G1. It should be noted that the locking part 52 can also engage with the connecting piece 33 on the joint end 3b side. Here, Figure 6 The reference numeral G2 in the attached diagram indicates the gap between adjacent connecting pieces 33 in the circumferential direction. For example... Figure 6 As shown, in the spacer expander 2, the first bent portion 521, connected to the end of the insert portion 51, extends from the outer peripheral surface S1 side of the expander body 3 through the gap G2 to the opposite inner peripheral surface S2 side. The second bent portion 522, connected to the first bent portion 521, folds back and extends from the inner peripheral surface S2 side through the adjacent gap G2 to the opposite outer peripheral surface S1 side. Thus, the connecting piece 33 is clamped from both sides circumferentially by the first bent portion 521 and the second bent portion 522. Furthermore, the front end of the second bent portion 522 abuts against the connecting piece 33 and does not protrude to the outer peripheral side of the expander body 3. Here, Figure 7 It means Figure 6 A sectional view of section A-A. For example... Figure 7As shown, a notch 38 for the locking part 52 to be inserted is formed at the inner end E2 of the connecting piece 33 corresponding to the bent portion of the locking part 52. Therefore, the linear member 5 will not protrude to the inner circumference of the expander body 3. However, it is acceptable for the linear member 5 to protrude to the inner circumference of the expander body 3 within a range that does not interfere with (contact) the inner wall of the annular groove 30, and the notch 38 may not need to be formed in the expander body 3. In the spacer expander 2, the insert 51 engages with the expander groove 4 formed on the outer circumferential surface S1 side of the expander body 3, and the locking part 52 engages with the notch 38 formed on the inner circumferential surface S2 side of the expander body 3, thereby restricting the radial relative movement of the linear member 5 with respect to the expander body 3. Furthermore, in the spacer expander 2, the connecting piece 33 on the seam end 3a side is clamped from both sides in the circumferential direction by the first bending portion 521 and the second bending portion 522. The front end of the second bending portion 522 abuts against the adjacent connecting piece 33 of the connecting piece 33, thus restricting the relative circumferential movement of the linear member 5 relative to the seam end 3a. As a result, one end (locking portion 52) of the linear member 5 is locked on the seam end 3a side of the expander body 3, preventing the linear member 5 from falling off the expander body 3. On the other hand, the other end of the linear member 5 is not locked on the seam end 3b side of the expander body 3. Therefore, in the spacer expander 2, the seam end 3b can slide circumferentially along the insert portion 51. It should be noted that, alternatively, at least a portion of the opening of the notch 37 of the expander groove 4 can be sealed with resin on the side of the joint end 3b, so that the insert 51 will not fall off the expander groove 4 when the joint end 3b slides along the insert 51 in the circumferential direction.

[0070] It should be noted that, alternatively, a coating may be formed on the surface of at least one of the following: resin coating, nitriding coating, Ni-P plating coating, chromium plating coating, PVD coating, and DLC coating. "Resin coating" refers to a coating formed from resin materials. "Nitriding coating" refers to a coating formed by nitrogen permeating to the metal surface through nitriding. "Ni-P plating coating" refers to a coating formed by electroless Ni-P plating. "Chromium plating coating" refers to a coating formed by chromium plating. Chromium plating is also known as industrial chromium plating. "PVD (physical vapor deposition) coating" refers to a coating formed by the PVD method. "DLC (Diamond Like Carbon) coating" refers to an amorphous hard carbon coating mainly composed of hydrocarbons and carbon allotropes. By forming such a coating, the wear resistance of the scraper 1 or the expander body 3 can be improved.

[0071] [Installation of the oil ring piston]

[0072] Next, the method for installing the oil ring 40 onto the piston 20 according to the embodiment will be described. To install the oil ring 40 onto the piston 20, firstly, a spacer expander 2, in which a linear member 5 is embedded in the expander groove 4, is attached to the annular groove 30 of the piston 20. Then, a pair of scrapers 1, 1 are attached to the annular groove 30, separated from each other by the spacer expander 2. When attaching the spacer expander 2 to the annular groove 30, the spacer expander 2 is inserted into the annular groove 30 while widening the joint G1 of the expander body 3. It is attached to the annular groove 30 by abutting one pair of joint ends 3a, 3b of the expander body 3 against each other within the annular groove 30. As described above, in the spacer expander 2, the linear member 5 is maintained in the expander groove 4 across the joint G1, and the joint end 3b can slide circumferentially along the embedded portion 51 of the linear member 5. Therefore, when the joint G1 of the expander body 3 expands, the joint end 3b moves along the fitting portion 51 and expands while being guided by the fitting portion 51. Furthermore, when the spacer expander 2 is fitted into the annular groove 30 and the joint G1 is closed, the joint end 3b moves along the fitting portion 51 and closes while being guided by the fitting portion 51. Thus, when the spacer expander 2 is installed onto the piston 20, the expander body 3 maintains an orientation where the joint ends 3a and 3b are opposite each other, preventing the joint ends 3a and 3b from overlapping.

[0073] [Function / Effect]

[0074] As described above, the spacer expander 2 of the embodiment includes: an expander body 3, which is formed in a ring shape along the circumference of the oil ring 40 and is formed in a wave shape that is continuous in the circumference when viewed from the radial direction of the oil ring 40; an expander groove 4, which is formed in the expander body 3 in such a way that it crosses the seam G1 and extends along the circumference of the oil ring 40; and a linear member 5, including an insert portion 51, which is formed in an arc shape along the circumference of the oil ring 40, and the insert portion 51 maintains the expander body 3 in an orientation in which a pair of seam ends 3a, 3b are opposite each other by being inserted into the expander groove 4 in such a way that it crosses the seam G1.

[0075] According to the embodiment of the spacer expander 2, it can prevent the ends of the joints 3a and 3b from overlapping each other radially and axially. This prevents the scraper 1 from being difficult to install during the installation of the oil ring 40 onto the piston 20, and prevents the oil ring 40 from failing to function properly. Furthermore, the axial width and radial thickness of the axially wavy spacer expander are narrow, making it difficult to provide holes for inserting the linear member. However, the spacer expander 2 of this embodiment employs a structure in which the linear member 5 is fitted into a groove. Therefore, even with an axially wavy spacer expander, the overlap of the ends of the joints can be prevented. Moreover, the spacer expander 2 of this embodiment employs a structure in which the linear member 5 is fitted into an expander groove 4 formed in the expander body 3 and open to the outside. Therefore, unlike techniques that use pins or the like to fix the joint ends together, the expander body 3 can be guided by the linear member 5 to expand / contract in diameter, thus allowing for easy installation and removal of the spacer expander 2 relative to the piston 20. Therefore, the replacement of the oil ring 40, including the scraper 1 and the spacer expander 2, becomes easier. Therefore, the oil ring 40 can be used as a spare part (maintenance component).

[0076] Furthermore, in the embodiment, the expander groove 4 of the spacer expander 2 is formed on the outer peripheral surface S1 of the expander body 3 by notches 37 provided at the outer ends E1 of a plurality of connecting pieces 33 arranged circumferentially along the oil ring 40. Then, the width w1 of the axially extending linear member 5's fitting portion 51 is smaller than the axially extending width b1 of the outer ends E1 of the connecting pieces 33 (in this example, the distance between the lower surface of the upper support portion 312 and the upper surface of the lower support portion 322). Accordingly, by making the axially extending width w1 of the fitting portion 51 smaller than the axially extending width b1 of the outer ends E1 of the connecting pieces 33, the fitting portion 51 can be fitted between a pair of scrapers 1, 1.

[0077] Furthermore, in the spacer expander 2 of the embodiment, the radius of curvature r2 of the arc at the inner peripheral end 512 of the fitting portion 51 of the linear member 5 in the free state is less than or equal to the radius of curvature R1 of the outermost periphery of the expander body 3 after the two seam ends 3a and 3b in the free state are joined together. Therefore, the spacer expander 2 can maintain the linear member 5 in the expander groove 4 across the seam G1. It should be noted that the radius of curvature r2 of the linear member 5 in the free state is preferably within the range of 0% to -10% relative to the radius of curvature R1 of the expander body 3 after the two seam ends 3a and 3b in the free state are joined together, and more preferably within the range of 0% to -5%. This makes it difficult for the linear member 5 to fall out of the expander groove 4. However, the present invention is not limited to this.

[0078] Here, regarding the circumferential length of the fitting portion 51 of the linear member 5, it is preferable that the length from one seam end (the seam end on the side where the locking portion 52 is fixed) to the other seam end is 2 mm or more. Furthermore, the locking portion 52 is not a necessary component of this invention. That is, the linear member of this invention may not have a locking portion, and the entire linear member may be a fitting portion. In this case, the circumferential length of the fitting portion is preferably at least 1 / 2 of the full circumference of the expander body, more preferably at least 2 / 3 of the full circumference of the expander body. By employing this method, the inner circumferential surface (more specifically, the inner circumferential end) of the linear member is fitted with the outer circumferential surface (more specifically, the bottom of the expander groove) of the expander body, making it difficult for the linear member to fall off. Furthermore, when the linear member does not have a locking portion, both seam ends of the expander body can slide circumferentially along the linear member, thereby guiding the seam ends by the linear member and preventing the seam ends from overlapping.

[0079] Furthermore, the present invention can also fix one end of the linear member to the expander body by means of bonding, welding, brazing, etc., instead of the aforementioned locking part 52. Alternatively, the flash formed on the linear member and the expander body can be used to lock one end of the linear member to the expander body by hooking the flash.

[0080] [Variation Example]

[0081] Hereinafter, variations of the embodiment will be described. In the following description, the focus will be on the differences from the oil ring 40 described above, and detailed descriptions will be omitted by using the same reference numerals to refer to the same components.

[0082] [Variation Example 1]

[0083] Figure 8 This is a partial cross-sectional view of an internal combustion engine 100A with an oil ring 40A according to Modified Example 1 of the embodiments. Figure 8 The diagram shows a cross-section orthogonal to the circumferential direction of oil ring 40A. For example... Figure 8 As shown, the difference between the spacer expander 2A of the oil ring 40A in Modified Example 1 and the spacer expander 2 is that the expander groove 4A is formed on the inner circumferential surface S2 of the expander body 3A.

[0084] like Figure 8As shown, in the spacer expander 2A, a notch 37 is formed at the inner end E2 of the radially inner end of the connecting piece 33, which serves as the expander body 3A, opening radially inward (inner circumferential side). The inner wall of the notch 37 is formed as a convex arc shape extending radially outward. The notches 37 are provided on a plurality of connecting pieces 33 in a circumferential arrangement. As a result, an expander groove 4A is formed on the inner circumferential surface S2 of the expander body 3A, extending circumferentially across the joint G1 and opening to the inner circumferential side. It should be noted that in this example, the expander groove 4A is formed axially at the center of the connecting piece 33, but the axial position of the expander groove 4A can also be close to the upper piece 31 side or the lower piece 32 side. The fitting portion 51 of the linear member 5A is fitted into the expander groove 4A in a manner that crosses the joint G1. The axial width w1 of the insert portion 51 of the linear member 5A is smaller than the axial width b2 of the inner end portion E2 of the connecting piece 33, that is, the distance between the lower surface of the upper ear portion 311 and the upper surface of the lower ear portion 321 in the axial direction.

[0085] In this modified example 1, the dimensions of R2 and r1 are set such that, in the free state, the radius of curvature r1 of the arc at the outer peripheral end 511 of the fitting portion 51 of the linear member 5A is greater than or equal to the radius of curvature R2 of the innermost periphery of the expander body 3A after the ends 3a and 3b of the joint are joined together. This allows the linear member 5A to be fitted into the expander groove 4A. Here, when the dimension of r1 is greater than the dimension of R2, the linear member 5A is reduced in diameter by fitting it into the expander groove 4A, thus generating a self-tension to expand its diameter. Consequently, the linear member 5A is fitted into the spacer expander 2A in the expander groove 4A, and the outer peripheral end 511 of the linear member 5A presses the expander body 3A radially outward. This maintains the state where the linear member 5A is fitted into the expander groove 4A across the joint G1.

[0086] Figure 9 This is a top view of a portion of the spacer expander 2A in Modified Example 1 of the embodiment. In Modified Example 1, the locking portion 52A of the linear member 5A is connected to one end of the fitting portion 51 and is bent in a manner protruding radially outward. The locking portion 52A includes a first bent portion 521A extending radially outward from one end of the fitting portion 51 and a second bent portion 522A bent from the front end of the first bent portion 521A and extending radially inward. The second bent portion 522A includes one end of the linear member 5A. Figure 9As shown, in the spacer expander 2A, the first bent portion 521A, connected to the end of the insert portion 51, extends from the inner circumferential surface S2 side of the expander body 3A through the gap G2 to the opposite outer circumferential surface S1 side. The second bent portion 522A, connected to the first bent portion 521A, folds back and extends from the outer circumferential surface S1 side through the adjacent gap G2 to the opposite inner circumferential surface S2 side. Thus, the connecting piece 33 is clamped from both sides circumferentially by the first bent portion 521A and the second bent portion 522A. Furthermore, the front end of the second bent portion 522A abuts against the connecting piece 33 and does not protrude to the inner circumferential side of the expander body 3A. Here, Figure 10 It means Figure 9 A sectional view of section B-B. For example... Figure 10 As shown, a notch 38 for the locking part 52A to be inserted is formed at the outer end E1 of the connecting piece 33 corresponding to the bent portion of the locking part 52A. Therefore, the linear member 5A does not protrude to the outer periphery of the expander body 3A. In the spacer expander 2A, the insert portion 51 engages with the expander groove 4A formed on the inner peripheral surface S2 side of the expander body 3A, and the locking part 52A engages with the notch 38 formed on the outer peripheral surface S1 side of the expander body 3A, thereby restricting the radial relative movement of the linear member 5A relative to the expander body 3A. Furthermore, in the spacer expander 2A, the connecting piece 33 on the seam end 3a side is clamped from both circumferential sides by the first bent portion 521A and the second bent portion 522A, with the front end of the second bent portion 522A abutting against the adjacent connecting piece 33 of the connecting piece 33, thus restricting the circumferential relative movement of the linear member 5A relative to the seam end 3a. Thus, one end of the linear member 5A (locking part 52A) is locked on the seam end 3a side of the expander body 3A, preventing the linear member 5A from falling off the expander body 3A. On the other hand, the other end of the linear member 5A is not locked on the seam end 3b side of the expander body 3A, so in the spacer expander 2A, the seam end 3b can slide circumferentially along the insert part 51.

[0087] According to the spacer expander 2A of Modification 1, similarly to the spacer expander 2 described above, by maintaining the expander body 3A in an orientation where the joint ends 3a and 3b are opposite each other, it is possible to prevent the joint ends 3a and 3b from overlapping each other radially and axially. Furthermore, the expander groove 4A of the spacer expander 2A of Modification 1 is formed on the inner circumferential surface S2 of the expander body 3A through notches 37 provided at the inner ends E2 of a plurality of connecting pieces 33 arranged circumferentially along the oil ring 40. Then, the width w1 of the insert portion 51 of the axially extending linear member 5A is smaller than the width b2 of the inner ends E2 of the axially extending connecting piece 33 (in this example, the distance between the lower surface of the upper ear 311 and the upper surface of the lower ear 321). Accordingly, by making the axial width w1 of the insert portion 51 smaller than the axial width b2 of the inner end E2 of the connecting piece 33, the insert portion 51 can be fitted into the inner circumferential surface S2 of the expander body 3A. Furthermore, in the spacer expander 2A of Modified Example 1, the radius of curvature r1 of the arc at the outer circumferential end 511 of the insert portion 51 of the linear member 5A in the free state is greater than or equal to the innermost radius of curvature R2 of the expander body 3A in the state after the ends 3a and 3b of the joint in the free state are joined together. This maintains the state in which the linear member 5A is fitted across the joint G1 into the expander groove 4A. It should be noted that the radius of curvature r1 of the linear member 5A in the free state is preferably within the range of 0% to +10% relative to the radius of curvature R2 of the expander body 3 in the state after the ends 3a and 3b of the joint in the free state are joined together, and more preferably within the range of 0% to +5%. Therefore, the linear member 5A is less likely to detach from the expander groove 4A. However, the present invention is not limited thereto.

[0088] [Variation Example 2]

[0089] Figure 11 This is a partial cross-sectional view of an internal combustion engine 100B with an oil ring 40B according to Modified Example 2 of the embodiment. Figure 11 The diagram shows a cross-section orthogonal to the circumferential direction of oil ring 40B. For example... Figure 11 As shown, the difference between the spacer expander 2B of the oil ring 40B in Modified Example 2 and the spacer expander 2 is that the expander groove 4B is formed on the upper surface S3 of the expander body 3B.

[0090] like Figure 11As shown, in the spacer expander 2B, a notch 37 opening upwards (to the combustion chamber side) is formed on the upper plate 31 of the expander body 3B. More specifically, the notch 37 is formed between the upper ear portion 311 and the upper support portion 312 in the upper plate 31, that is, it is formed on the upper base portion 310. The inner wall of the notch 37 is formed into an arc shape convex towards the crankcase side. The notches 37 are arranged circumferentially on multiple upper plates 31. Thus, an expander groove 4B extending circumferentially and opening upwards is formed on the upper surface S3 of the expander body 3B. It should be noted that in this example, the expander groove 4B is formed radially at the center of the upper base portion 310, but the radial position of the expander groove 4B can also be close to the outer or inner circumferential side. The fitting portion 51 of the linear member 5B is fitted into the expander groove 4B across the joint G1. Figure 11 As shown, the radial thickness t1 of the mounting portion 51 of the linear member 5B is smaller than the radial thickness (the radial distance between the outermost and innermost circumferences) of the expander body 3. More specifically, the thickness t1 is smaller than the radial thickness a1 of the upper base portion 310 of the upper plate 31 (in this example, the radial distance between the upper ear portion 311 and the upper support portion 312). In Modified Example 2, the linear member 5B, like the linear member 5, is secured to the expander body 3B by the locking portion 52.

[0091] According to the spacer expander 2B of Modification 2, similarly to the spacer expander 2 described above, by maintaining the expander body 3B in an orientation where the ends 3a and 3b of the butt joint are opposite to each other, it is possible to prevent the ends 3a and 3b of the butt joint from overlapping each other in the radial and axial directions. Furthermore, in the case of the spacer expander 2B of Modification 2, by making the radial thickness t1 of the insert portion 51 smaller than the radial thickness a1 of the upper base portion 310 (in this example, the radial distance between the upper ear portion 311 and the upper support portion 312), the insert portion 51 can be fitted into the upper base portion 310.

[0092] In the spacer expander 2B of Modified Example 2, it is preferable that the radius of curvature r1 of the arc at the outer peripheral end 511 of the fitting portion 51 of the linear member 5B in the free state is +10% or less of the radius of curvature R1 of the outermost periphery of the expander body 3B after the butt joint ends 3a and 3b are joined together in the free state, and the radius of curvature r2 of the arc at the inner peripheral end 512 of the fitting portion 51 of the linear member 5B in the free state is -10% or more of the radius of curvature R2 of the innermost periphery of the expander body 3B after the butt joint ends 3a and 3b are joined together in the free state. This makes it difficult for the linear member 5B to fall out of the expander groove 4B, reducing the resistance during the reduction or expansion of the expander body 3B's diameter. It should be noted that r1 can be equal to or less than R1, and r2 can be equal to or greater than R2. Here, when the radius of curvature r1 of the arc at the outer peripheral end 511 of the linear member 5B is greater than the radius of curvature R1 of the outermost periphery of the expander body 3B—that is, when r1 is greater than R1 but less than +10% of R1—the linear member 5B is fitted into the expander groove 4B, causing the linear member 5B to shrink in diameter. This generates self-tension in the linear member, resulting in the outer peripheral end 511 of the linear member 5B pressing the expander body 3B radially outward. Similarly, when the radius of curvature r2 of the arc at the inner peripheral end 512 of the linear member 5B is less than the radius of curvature R2 of the innermost periphery of the expander body 3B—that is, when r2 is greater than -10% of R2 but less than R2—the linear member 5B is fitted into the expander groove 4B, causing the linear member 5B to expand in diameter. This generates self-tension in the linear member 5B, resulting in the inner peripheral end 512 of the linear member 5B pressing the expander body 3B radially inward. Thus, the linear member 5B is maintained in the state where it is fitted across the joint G1 into the expander groove 4B. However, the conditions R1, R2, r1, and r2 described above do not limit the present invention.

[0093] [Variation Example 3]

[0094] Figure 12 This is a partial cross-sectional view of an internal combustion engine 100C with an oil ring 40C according to modified example 3 of the embodiment. Figure 12 The diagram shows a cross-section orthogonal to the circumferential direction of oil ring 40C. For example... Figure 12 As shown, the difference between the spacer expander 2C of the oil ring 40C in Modified Example 3 and the spacer expander 2 is that the expander groove 4C is formed on the lower surface S4 of the expander body 3C.

[0095] like Figure 12As shown, in the spacer expander 2C, a notch 37 opening downwards (crankcase side) is formed in the lower piece 32 of the expander body 3C. More specifically, the notch 37 is formed between the lower ear portion 321 and the lower support portion 322 in the lower piece 32, that is, it is formed in the lower base portion 320. The inner wall of the notch 37 is formed into an arc shape convex towards the combustion chamber side. The notches 37 are provided in a plurality of lower pieces 32 in a circumferential arrangement. Thus, an expander groove 4C extending circumferentially and opening downwards is formed on the lower surface S4 of the expander body 3C. It should be noted that in this example, the expander groove 4C is formed radially at the center of the lower base portion 320, but the radial position of the expander groove 4C can also be close to the outer or inner circumferential side. The fitting portion 51 of the linear member 5C is fitted into the expander groove 4C in a manner that crosses the joint G1. Figure 12 As shown, the radial thickness t1 of the fitting portion 51 of the linear member 5C is smaller than the radial thickness (the radial distance between the outermost and innermost circumferences) of the expander body 3. 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). In the modified example 3, the linear member 5C, like the linear member 5, is secured to the expander body 3C by the locking portion 52.

[0096] According to the spacer expander 2C of Modified Example 3, similarly to the spacer expander 2 described above, by maintaining the expander body 3C in an orientation where the joint ends 3a and 3b are opposite each other, it is possible to prevent the joint ends 3a and 3b from overlapping each other in the radial and axial directions. Furthermore, in the case of the spacer expander 2C of Modified Example 3, by making the radial thickness t1 of the insert portion 51 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), the insert portion 51 can be fitted into the lower base portion 320.

[0097] Here, in the spacer expander 2C of Modification 3, similarly to Modification 2, it is preferable that the radius of curvature r1 of the arc at the outer peripheral end 511 of the fitting portion 51 of the linear member 5C in the free state is +10% or less of the radius of curvature R1 of the outermost periphery of the expander body 3C after the butt joint ends 3a and 3b are joined together in the free state, and the radius of curvature r2 of the arc at the inner peripheral end 512 of the fitting portion 51 of the linear member 5C in the free state is -10% or more of the radius of curvature R2 of the innermost periphery of the expander body 3C after the butt joint ends 3a and 3b are joined together in the free state. This makes it difficult for the linear member 5C to fall out of the expander groove 4C, reducing the resistance during the reduction or expansion of the expander body 3C's diameter. It should be noted that r1 can be equal to or less than R1, and r2 can be equal to or greater than R2. Here, when r1 is greater than R1 (that is, r1 is greater than R1 but less than +10% of R1) and r2 is less than R2 (that is, r2 is more than -10% of R2 but less than R2), self-tension is generated in the linear member 5C, thus maintaining the state in which the linear member 5C is fitted across the joint G1 into the expander groove 4C. However, the conditions of R1, R2, r1, and r2 described above do not limit the present invention.

[0098] [Variation Example 4]

[0099] Figure 13 This is a partial cross-sectional view of an internal combustion engine 100D with an oil ring 40D according to Modified Example 4 of the embodiments. Figure 13 The diagram shows a cross-section orthogonal to the circumferential direction of oil ring 40D. For example... Figure 13 As shown, the difference between the spacer expander 2D of the oil ring 40D in Modified Example 4 and the spacer expander 2 is that the expander body 3D does not have an upper support portion 312 and a lower support portion 322. For example... Figure 13 As shown, 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. Then, regarding the spacer expander 2D in Modification 4, by making the width w1 of the insert portion 51 of the axially extending linear member 5D smaller than the width b1 of the outer end E1 of the connecting piece 33, the insert portion 51 can be fitted into the outer peripheral surface S1 of the expander body 3D.

[0100] [Variation Example 5]

[0101] Figure 14 This is a partial cross-sectional view of an internal combustion engine 100E with an oil ring 40E according to Modified Example 5 of the embodiments. Figure 14 The diagram shows a cross-section orthogonal to the circumferential direction of oil ring 40E. For example... Figure 14As shown, the difference between the spacer expander 2E of the oil ring 40E in Modified Example 5 and the spacer expander 2A in Modified Example 1 is that the expander body 3E does not have an upper support portion 312 and a lower support portion 322. Furthermore, regarding the spacer expander 2E in Modified Example 5, by making the width w1 of the insert portion 51 of the axially oriented linear member 5E smaller than the width b2 of the inner end portion E2 of the axially oriented connecting piece 33, the insert portion 51 can be fitted into the inner circumferential surface S2 of the expander body 3E.

[0102] [Variation Example 6]

[0103] Figure 15 This is a partial cross-sectional view of an internal combustion engine 100F with an oil ring 40F according to Modified Example 6 of the embodiments. Figure 15 The diagram shows a cross-section orthogonal to the circumferential direction of oil ring 40F. (See diagram for example.) Figure 15 As shown, the difference between the spacer expander 2F of the oil ring 40F in Modified Example 6 and the spacer expander 2B in Modified Example 2 is that the expander body 3F does not have an upper support portion 312 and a lower support portion 322. In Modified Example 6, 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 E1 of the connecting piece 33. Then, regarding the spacer expander 2F of Modified Example 6, by making the radial thickness t1 of the insert portion 51 of the linear member 5F smaller than the radial thickness a1 of the upper base portion 310, the insert portion 51 can be fitted into the upper base portion 310.

[0104] [Variation Example 7]

[0105] Figure 16 This is a partial cross-sectional view of an internal combustion engine 100G with an oil ring 40G according to modified example 7 of the embodiment. Figure 16 The diagram shows a cross-section orthogonal to the circumferential direction of the oil ring 40G. For example... Figure 16 As shown, the difference between the spacer expander 2G of the oil ring 40G in Modified Example 7 and the spacer expander 2C in Modified Example 3 is that the expander body 3G does not have an upper support portion 312 and a lower support portion 322. 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 E1 of the connecting piece 33. Then, regarding the spacer expander 2G in Modified Example 7, by making the radial thickness t1 of the insert portion 51 of the linear member 5G smaller than the radial thickness a2 of the lower base portion 320, the insert portion 51 can be fitted into the lower base portion 320.

[0106] [Variation Example 8]

[0107] Next, the spacer expander for the oil ring in variation 8 of the embodiment will be described. Figure 17 This is a top view of a portion of the spacer 2H in variation 8 of the embodiment. Figure 18 This is a top view of the linear member 5H of the modified embodiment 8 (a view obtained from the upper axial side).

[0108] like Figure 18 As shown, the linear member 5H used for the spacer expander 2H and in Figure 4 The difference between the linear member 5 described above and the one described below is that locking portions 53 are provided at both ends of the fitting portion 51. The locking portions 53 are formed by bending the ends of the linear member 5H. For example... Figure 18 As shown, the locking portion 53 includes a first bent portion 531 extending radially inward from the end of the fitting portion 51 and a second bent portion 532 bent from the front end of the first bent portion 531 and extending circumferentially outward (in the opposite direction to the fitting portion 51). The linear member 5H is integrally formed into a generally U-shape by the fitting portion 51 and a pair of locking portions 53, 53. Hereinafter, when describing the pair of locking portions 53, 53 of the linear member 5H separately, the locking portion 53 connected to one end of the fitting portion 51 is designated as the first locking portion 53a, and the locking portion 53 connected to the other end of the fitting portion 51 is designated as the second locking portion 53b. In this example, the first locking portion 53a engages with the connecting piece 33 on the seam end 3a side, and the second locking portion 53b engages with the connecting piece 33 on the seam end 3b side.

[0109] like Figure 17 As shown, regarding the expander body 3H of the spacer expander 2H, except that the notch 38 is provided at the inner end E2 of the two connecting pieces 38 located on opposite sides of each other across the seam G1, it is similar to... Figures 1-3 The expander body 3 described above is the same. That is, an expander groove 4 is formed on the outer peripheral surface S1 of the expander body 3 through multiple notches 37 provided at the outer ends E1 of the multiple connecting pieces 33. Figure 17 As shown, the expander body 3H has notches 38 for engaging the second bent portion 532 of the first locking portion 53a and for engaging the second bent portion 532 of the second locking portion 53b. A pair of notches 38 are formed on the inner end E2 of the connecting piece 33 on the joint end 3a side and the inner end E2 of the connecting piece 33 on the joint end 3b side.

[0110] like Figure 17 As shown, in the spacer expander 2H, there is a pair of locking parts 53. The first bending part 531 of 53 extends from the outer peripheral side to the inner peripheral side of the expander body 3H through the gap G2, and the second bending part 532 engages with the inner end E2 of the connecting piece 33.

[0111] In Modification 8, after the expander body 3H is fitted into the annular groove 30, the linear member 5 is embedded in the expander body 3H, thereby preventing the overlap of one pair of joint ends 3a and 3b by the embedding part 51. Thus, a pair of scrapers 1, 1 can be installed in the spacer expander 2H while preventing the overlap of one pair of joint ends 3a and 3b of the spacer expander 2H.

[0112] To allow the linear member 5H to be fitted into the expander body 3H, the locking portion 53 overcomes the elasticity of the linear member 5H and is in a state of contraction towards the circumference and inward (towards the fitting portion 51). The fitting portion 51 is inserted into the expander groove 4, and the locking portion 53 is inserted between the connecting pieces 33. The second bent portion 532 is then fitted into the notch 38, thereby engaging with the connecting piece 33. With the linear member 5H fitted into the expander body 3H, the locking portion 53 generates a restoring force that causes it to extend outward due to the elasticity of the linear member 5H. Therefore, the first bent portion 531 is in a state of being pushed (supported) relative to the connecting piece 33. Thus, the engagement of the second bent portion 532 with the connecting piece 33 is maintained.

[0113] In the spacer expander 2H, the fitting portion 51 of the linear member 5H is fitted into the expander groove 4 formed on the outer peripheral surface S1 side of the expander body 3H. A pair of locking portions 53, 53 provided at both ends of the fitting portion 51 are fitted into the inner end E2 of the connecting piece 33 of the expander body 3H, thereby restricting the relative movement of the linear member 5H in the radial and circumferential directions relative to the expander body 3H. Thus, the linear member 5H is locked to the expander body 3H, preventing the linear member 5H from falling off the expander body 3H. In the modified example 8, by providing locking portions 53 at both ends of the fitting portion 51, the state in which the linear member 5H is fitted into the expander body 3H can be reliably maintained compared to the case where locking portions 53 are provided at only one end. It should be noted that the shape of the locking portion 53 is not limited to Figure 17 The shape shown. For example, the locking part 53 can also be with... Figure 4 Similarly, the locking portion 52 shown is also a shape in which the second bending portion 532 bends from the front end of the first bending portion 531 and extends radially outward. Furthermore, it is permissible for the linear member 5H to protrude to the inner circumference of the expander body 3H within a range that does not interfere with (contact) the inner wall of the annular groove 30, and it is also permissible not to form a notch 38 in the expander body 3H.

[0114] <Other>

[0115] The preferred embodiments of the present invention have been described above, but the various methods described above can be combined as much as possible.

[0116] Explanation of reference numerals in the attached figures

[0117] 100, 100A, 100B, 100C, 100D, 100E, 100F, 100G: Internal combustion engine;

[0118] 10: Cylinder;

[0119] 20: Piston;

[0120] 30: Annular groove;

[0121] 40, 40A, 40B, 40C, 40D, 40E, 40F, 40G: Oil rings;

[0122] 1: Scraper blade;

[0123] 2, 2A, 2B, 2C, 2D, 2E, 2F, 2G, 2H: Spacing expanders;

[0124] 3, 3A, 3B, 3C, 3D, 3E, 3F, 3G, 3H: Expander body;

[0125] 4, 4A, 4B, 4C, 4D, 4E, 4F, 4G: Expander slots;

[0126] 5, 5A, 5B, 5C, 5D, 5E, 5F, 5G, 5H: Linear components.

Claims

1. A spacer expander, disposed in the oil ring of a piston mounted in an internal combustion engine, between a pair of axially separated scrapers of the oil ring, wherein, The interval expander includes: The expander body is formed in a ring shape along the circumference of the oil ring, and applies force to the pair of scrapers in the radial direction outward of the oil ring. The expander body includes a pair of joint ends that form a joint by being opposed to each other, and is formed in a continuous wavy shape in the circumferential direction when viewed from the radial direction of the oil ring. An expander groove is formed in the expander body in such a way that it spans the seam and extends circumferentially along the oil ring; as well as A linear component includes an insert portion that is formed in an arc shape along the circumference of the oil ring and is fitted into the expander groove in a manner that spans the seam. The linear member also includes a locking portion located at one end of the fitting portion. The locking portion includes: a first bent portion extending radially inward from one end of the insert portion toward the oil ring; And a second bend, which bends from the front end of the first bend and extends radially outward from the oil ring.

2. The spacer expander according to claim 1, wherein, The expander body includes: Multiple upper plates are arranged at intervals along the circumference of the oil ring; A plurality of lower plates are arranged such that, when the oil ring is mounted on the piston, they are positioned axially on the crankcase side of the oil ring relative to the plurality of upper plates in the internal combustion engine; each of the lower plates is arranged alternately with each of the upper plates in the circumferential direction of the oil ring; and Multiple connecting pieces connect the upper and lower pieces that are adjacent in the circumferential direction of the oil ring. The upper plate includes: an upper base portion; and an upper ear portion, which stands upright on the inner side of the upper base portion formed radially on the oil ring, pressing the upper scraper of the pair of scrapers located on the combustion chamber side in the internal combustion engine towards the radial outer side of the oil ring. The lower blade includes: a lower base portion; and a lower ear portion, which stands upright on the inner side of the lower base portion formed radially on the oil ring, pressing the lower scraper of the pair of scrapers located on the crankcase side in the internal combustion engine toward the radial outer side of the oil ring.

3. The spacer expander according to claim 2, wherein, The expander groove is formed on the outer peripheral surface of the expander body by a plurality of notches, which are arranged along the circumference of the oil ring at the outer ends of the plurality of connecting pieces, which are the radially outer ends of the oil ring. The width of the axially mounted portion of the oil ring is smaller than the width of the outer end of the axially mounted connecting piece.

4. The spacer expander according to claim 2, wherein, The expander groove is formed by multiple notches on the inner circumferential surface of the expander body. The multiple notches are arranged along the circumference of the oil ring at the inner end of the radially inner end of the oil ring among the multiple connecting pieces. The width of the axially mounted portion of the oil ring is smaller than the width of the inner end of the axially mounted connecting piece.

5. The spacer expander according to any one of claims 1 to 3, wherein, The expander groove is formed on the outer peripheral surface of the expander body. In the free state before the oil ring is installed on the piston, the radius of curvature of the arc at the inner circumferential end of the insert is less than the radius of curvature of the outermost circumference of the expander body after the ends of the butt joints are joined together.

6. The spacer expander according to any one of claims 1, 2, or 4, wherein, The expander groove is formed on the inner circumferential surface of the expander body. In the free state before the oil ring is installed on the piston, the radius of curvature of the arc at the outer peripheral end of the insert is greater than or equal to the radius of curvature of the innermost periphery of the expander body after the ends of the butt joints are joined together.

7. The spacer expander according to claim 2, wherein, The expander groove is formed by a plurality of notches provided on the upper base portion of the plurality of upper plates in a manner arranged circumferentially along the oil ring. The thickness of the insert portion in the radial direction of the oil ring is smaller than the thickness of the upper base portion in the same radial direction.

8. The spacer expander according to claim 2, wherein, The expander groove is formed by a plurality of notches provided on the lower base portion of the plurality of lower plates in a manner arranged along the circumference of the oil ring. The thickness of the insert portion in the radial direction of the oil ring is smaller than the thickness of the lower base portion in the same radial direction.

9. The spacer expander according to claim 1 or 2, wherein, The expander groove is formed on either of the two end faces of the expander body along the axial direction of the oil ring. In the free state before the oil ring is installed on the piston, the radius of curvature of the arc at the outer peripheral end of the insert is within +10% of the radius of curvature of the outermost periphery of the expander body after the ends of the two seams are joined together, and the radius of curvature of the arc at the inner peripheral end of the insert is more than -10% of the radius of curvature of the innermost periphery of the expander body after the ends of the two seams are joined together.

10. An oil ring, installed on a piston in an internal combustion engine, wherein, The oil ring includes: a pair of scrapers disposed axially apart in the oil ring; and a spacer expander disposed between the pair of scrapers. The interval expander includes: The expander body is formed in a ring shape along the circumference of the oil ring, and applies force to the pair of scrapers in the radial direction outward of the oil ring. The expander body includes a pair of joint ends that form a joint by being opposed to each other, and is formed in a continuous wavy shape in the circumferential direction when viewed from the radial direction of the oil ring. An expander groove is formed in the expander body in such a way that it spans the seam and extends circumferentially along the oil ring; as well as A linear component includes an insert portion that is formed in an arc shape along the circumference of the oil ring and is fitted into the expander groove in a manner that spans the seam. The linear member also includes a locking portion located at one end of the fitting portion. The locking portion includes: a first bent portion extending radially inward from one end of the insert portion toward the oil ring; And a second bend, which bends from the front end of the first bend and extends radially outward from the oil ring.

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