JP2022073716A - Combined oil ring - Google Patents

Abstract

To provide a technology capable of suppressing degradation of an oil scraping function, in a combined oil ring in which a main body ring and a coil expander are combined.SOLUTION: In a combined oil ring, a part of an inner peripheral surface S2 of a main body ring 1 forms holding portions H1 for holding a coil expander 2, and the holding portions permit movement along an axial direction of the main ring of the coil expander, so that the coil expander can change its posture between a first posture where a coil center C2 being a center of spiral of the coil expander on a cross-section orthogonal to a circumferential length direction of the main body ring and including a window hole V1, is positioned at an upper side being a combustion chamber side of an internal combustion engine in an axial direction with respect to an opening center C1 being a center in the axial direction of an inner peripheral opening V12 being an opening at an inner peripheral surface side of the window hole, and a second posture where the coil center is positioned at a lower side being a crank chamber side of the internal combustion engine in the axial direction with respect to the opening center on the cross-section.SELECTED DRAWING: Figure 4

Description

The present invention relates to a combined oil ring in which a main body ring and a coil expander are combined.

The internal combustion engine mounted on a general automobile adopts a configuration in which a combination of a piston ring including a compression ring (pressure ring) and an oil ring is mounted on the piston. In the axial direction of the piston, a compression ring is provided on the combustion chamber side and an oil ring is provided on the crank chamber side, and these exert their abilities by sliding on the inner wall surface of the cylinder. The oil ring has an oil seal function that suppresses the outflow of oil to the combustion chamber side (oil rise) by scraping off excess engine oil (lubricating oil) adhering to the inner wall surface of the cylinder to the crank side, and the lubricating oil film is the cylinder. By adjusting the amount of oil so that it is properly held on the inner wall surface, it has a function to prevent seizure of the piston due to the 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 formed of a main body ring in which a pair of rails sliding on the inner wall surface of the cylinder are integrated and a wire rod wound in a spiral shape to urge the main body ring to the inner wall surface of the cylinder. A two-piece combination oil ring combined with a coil expander is widely used. Such a combination oil ring has a window hole formed in the main body ring for discharging the oil scraped off by the rail part and accumulated between the rail parts to the inner peripheral surface side of the main body ring. be. When the oil is discharged from the window hole, the hydraulic pressure between the rail portions generated when the inner wall of the cylinder is slid is reduced, and the rail portion is suppressed from getting on the oil film. As a result, the oil scraping ability of the rail portion is maintained.

In relation to the two-piece combination oil ring, a technique for preventing the occurrence of problems such as dropping off when assembling to a piston by forming the coil expander into a substantially circular shape having overlapping portions in a free state is disclosed. (For example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2008-20670 Japanese Unexamined Patent Publication No. 63-21353

In the conventional technique, the oil discharge from the window hole of the main body ring is obstructed by the coil expander, and the oil may stay in the window hole. The oil accumulated in the window hole is not discharged promptly and deteriorates, so that insoluble substances such as carbon sludge are generated and accumulated in the window hole. This deposit is called a deposit. Conventionally, there has been a problem that the effect of reducing the hydraulic pressure between the rail portions is reduced due to the narrowing of the flow path of the window hole due to the accumulation of deposits, which leads to a decrease in the oil scraping ability of the rail portions.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a technique capable of suppressing a decrease in oil scraping ability in a combined oil ring in which a main body ring and a coil expander are combined. be.

In order to solve the above problems, the present invention has adopted the following configuration. That is, the present invention is an oil ring mounted on a piston of an internal combustion engine.
A coil expander formed in an annular shape by a spirally wound wire rod and arranged in an annular shape on the inner peripheral side of the main body ring to urge the main body ring radially outward. Equipped with
A pair of rail portions, which are formed in an annular shape around the axis of the main body ring and project outward in the radial direction of the main body ring, are provided on the outer peripheral portion of the main body ring side by side in the axial direction of the main body ring.
The main body ring is formed with a window hole that penetrates radially from the outer peripheral surface to the inner peripheral surface and connects to the space between the pair of rail portions.
A part of the inner peripheral surface forms a holding portion for holding the coil expander, and forms a holding portion.
By allowing the holding portion to move the coil expander along the axial direction of the main body ring, the coil expander is orthogonal to the peripheral length direction of the main body ring and has the coil extract in a cross section including the window hole. The center of the coil, which is the center of the spiral of the panda, is the center of the inner peripheral opening, which is the opening on the inner peripheral surface side of the window hole. Between the first posture located on the upper side and the second posture in which the coil center is located on the lower side of the internal combustion engine in the axial direction with respect to the opening center in the cross section. The posture can be changed,
When the coil expander is in the second posture, the holding portion is orthogonal to the circumferential length direction of the main body ring and passes through the upper edge of the inner peripheral opening in the cross section including the window hole, and the diameter of the main body ring. When the coil expander is located below the first straight line extending in the direction and the coil expander is in the first posture, the main body passes through the lower edge of the inner peripheral opening in the cross section. The coil expander is held so that the coil expander is located above the second straight line extending in the radial direction of the ring.
It is a combination oil ring.

That is, in the present invention, the coil expander can change the posture between the first posture in which the center of the coil is shifted upward with respect to the center of the opening of the window hole and the second posture in which the center is shifted downward. Axial movement of the coil expander body ring is allowed by the retainer. According to the present invention, the coil expander reciprocates between the first posture and the second posture so as to be interlocked with the reciprocating motion of the piston by the action of the inertial force accompanying the operation of the internal combustion engine, and the posture is repeatedly changed. .. By doing so, it is possible to shorten the period in which the positions of the coil center and the opening center match in the axial direction during the operation of the internal combustion engine, and it is possible to smoothly discharge the oil from the inner peripheral opening of the window hole. As a result, the accumulation of deposits is suppressed, and the oil existing in the space formed between the pair of rail portions flows through the window hole and is quickly discharged to the inner peripheral side of the main body ring. As a result, it is possible to suppress a decrease in the oil scraping ability of the combined oil ring.

Further, in the present invention,
The holding portion is the first in a cross section including the window hole orthogonal to the circumferential length direction of the main body ring at least one of the coil centers in the first posture and the second posture. The coil expander may be held so that the coil expander is located outside the first region sandwiched between the straight line and the second straight line.

According to this, oil can be discharged more smoothly from the inner peripheral opening, and deposit accumulation can be suppressed more reliably.

Further, in the present invention,
The holding portion is the first in a cross section including the window hole orthogonal to the circumferential length direction of the main body ring at least one of the first posture and the second posture of the coil expander. The coil expander may be held so that the coil expander is located outside the first region sandwiched between the one straight line and the second straight line.

According to this, the coil expander is arranged so as not to overlap the inner peripheral opening of the window hole in the radial direction of the main body ring in at least one of the first posture and the second posture. As a result, oil can be discharged more smoothly from the inner peripheral opening, and deposit accumulation can be suppressed more reliably.

Further, in the present invention, the holding portion includes the window hole orthogonal to the peripheral length direction of the main body ring in both the first posture and the second posture of the coil expander. The coil expander may be held so that the coil expander is located outside the first region in the cross section.

As a result, oil can be discharged more smoothly from the inner peripheral opening, and deposit accumulation can be suppressed more reliably.

Further, in the present invention,
The holding portion has an upper contact surface that comes into contact with the coil expander from above when the coil expander is in the first posture, and the coil when the coil expander is in the second posture. A lower contact surface that contacts the expander from below, a radial outer edge of the body ring on the upper contact surface, and a radial outer edge of the body ring on the lower contact surface. And also include a connecting surface extending in the axial direction of the main body ring.

According to this, the upward movement of the coil expander in the first posture is restricted by the upper contact surface, and the downward movement of the coil expander in the second posture is restricted by the lower contact surface. The coil expander is axially oriented between the first and second postures because the connecting surface connecting the upper and lower contact surfaces extends along the axial direction. Can be moved.

Further, at least one of a resin coating, a nitriding coating, a chrome plating treatment coating, a PVD treatment coating, and a DLC treatment coating is layered on at least one of the inner peripheral surface of the main body ring and the outer peripheral surface of the coil expander. A hard coating containing the above may be formed.

By forming such a hard coating, the wear resistance of the inner peripheral surface of the main body ring or the outer peripheral surface of the coil expander can be enhanced, and the slidability of the coil expander with respect to the main body ring can be improved. The "resin film" refers to a film formed of a resin material. Further, the "nitriding treatment film" refers to a film formed by infiltrating nitrogen into the metal surface by nitriding treatment. Further, the "chrome-plated coating" refers to a coating formed by chrome plating. Chromium plating is also called industrial chrome plating. Further, the "PVD (physical vapor deposition) treated coating film" refers to a coating film formed by the PVD method. The PVD method is a kind of vapor deposition method for forming a film by adhering particles emitted from a target to the surface of a substance, and is also called physical vapor deposition. The PVD method can include an ion plating method, a vacuum vapor deposition method, an ion beam vapor deposition method, a sputtering method, an FCVA (Filtered Cathodic Vacuum Arc) method and the like. Further, the "DLC (Diamond Like Carbon) treated film" refers to an amorphous hard carbon film mainly composed of hydrocarbons and allotropes of carbon.

According to the present invention, it is possible to suppress a decrease in oil scraping ability in a combined oil ring in which a main body ring and a coil expander are combined.

FIG. 1A is a partial cross-sectional view of an internal combustion engine provided with a combined oil ring according to an embodiment, FIG. 1A is a diagram showing a state in which the coil expander is in the first posture, and FIG. 1B is a view showing a state in which the coil expander is in the first posture. Is a diagram showing a state in which is in the second posture. It is a partially enlarged view which shows the combination oil ring which concerns on embodiment, FIG. 2 (a) is a figure which shows the state which the combination oil ring was visually recognized from the outside in the radial direction, and FIG. It is a figure which shows the state which was visually recognized from the inside. It is a perspective view which shows a part of the main body ring. It is sectional drawing of the combination oil ring when the coil expander is in the 1st posture. It is sectional drawing of the combination oil ring when the coil expander is in a 2nd posture. It is sectional drawing of the combination oil ring which concerns on the deformation example when the coil expander is a 1st posture. It is sectional drawing of the combination oil ring which concerns on the deformation example when the coil expander is a 2nd posture.

Hereinafter, preferred embodiments of the combined oil ring according to the present invention will be described with reference to the drawings. The configurations described in the following embodiments are not intended to limit the technical scope of the invention to those alone unless otherwise specified.

FIG. 1 is a partial cross-sectional view of an internal combustion engine including a combined oil ring according to an embodiment, and FIG. 1 (a) is a view showing a state in which the coil expander is in the first posture, FIG. 1 (b). Is a diagram showing a state in which the coil expander is in the second posture. In FIG. 1, a cross section orthogonal to the peripheral length direction of the main body ring indicated by reference numeral 1 is shown. FIG. 2 is a partially enlarged view showing a combination oil ring according to an embodiment, FIG. 2A is a view showing a state in which the combination oil ring is visually recognized from the outside in the radial direction, and FIG. 2B is a view showing a state in which the combination oil ring is visually recognized. It is a figure which shows the state which the ring was visually recognized from the inside in the radial direction. FIG. 2 shows a combined oil ring mounted on a piston of an internal combustion engine and inserted into a cylinder (hereinafter referred to as a used state).

As shown in FIGS. 1A and 1B, 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. As a result, the piston gap PC1 is formed. Further, a ring groove 30 having a substantially rectangular cross section is formed on the outer peripheral surface 20a of the piston 20. The ring groove 30 connects the upper wall 301 formed on the combustion chamber side, the lower wall 302 formed on the crank chamber side and facing the upper wall 301, and the inner peripheral edges of the upper wall 301 and the lower wall 302. It has a wall 303. The connection wall 303 is formed with a drain hole 304 for discharging the oil flowing in the ring groove 30 to an oil pan (not shown). The drain hole 304 may not be formed on the connection wall 303. The combination oil ring 40 (hereinafter referred to as the oil ring 40) according to the present embodiment is mounted on 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. As shown in FIGS. 1A and 1B, the oil ring 40 is a so-called two-piece oil ring. Specifically, the oil ring 40 is formed in an annular shape by a single main body ring 1 formed in an annular shape and a wire rod wound in a spiral shape, and is arranged on the inner peripheral side of the main body ring 1 to form a main body ring. A coil expander 2 for urging 1 to the outside in the radial direction is provided.

Hereinafter, as shown in FIGS. 1A and 1B, the direction along the central axis of the main body ring 1 is defined as the "vertical direction". Further, in the axial direction of the main body ring 1, the combustion chamber side (upper side in FIG. 1) in 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". Further, unless otherwise specified in the following description of the oil ring 40, the "peripheral length direction" refers to the peripheral length direction of the main body ring 1, and the "diametrical direction" refers to the radial direction of the main body ring 1. The "axial direction" refers to the direction along the central axis of the main body ring 1. Further, the "diameter direction of the coil expander" refers to the radial direction of the annular body formed by the coil expander 2. In the internal combustion engine 100, the oil ring 40 is mounted in the ring groove 30 in a state where the axial direction of the main body ring 1 and the coil expander 2 coincides with the axial direction of the piston 20. The oil ring 40 according to the present embodiment shows the posture of the coil expander 2 by holding the coil expander 2 while allowing the coil expander 2 to move in the axial direction of the main body ring 1 within a predetermined range. It is possible to change between the first posture shown in 1 (a) and the second posture shown in FIG. 1 (b). Hereinafter, each configuration of the oil ring 40 will be described.

The main body ring 1 is a ring having a substantially I-shaped cross section having a joint. A ring made of steel, cast iron, resin, or the like is used for the main body ring 1. As shown in FIG. 1, the main body ring 1 is formed as a component in which a pair of rail portions indicated by reference numeral 11 are integrated. The surface of the main body ring 1 includes an outer peripheral surface S1, an inner peripheral surface S2, an upper surface S3, and a lower surface S4. The upper surface S3 and the lower surface S4 are axial end faces of the main body ring 1 and are parallel to each other. The upper surface S3 and the lower surface S4 do not necessarily have to be parallel. The width (axial dimension) of the main body ring 1 is defined by the upper surface S3 and the lower surface S4. The outer peripheral surface S1 is a surface that connects the outer peripheral edges of the upper surface S3 and the lower surface S4. The inner peripheral surface S2 is a surface that connects the inner peripheral edges of the upper surface S3 and the lower surface S4. In the used state, the outer peripheral surface S1 is in sliding contact with the inner wall surface 10a of the cylinder 10, the inner peripheral surface S2 faces the connection wall 303 of the ring groove 30, the upper surface S3 faces the upper wall 301, and the lower surface S4 faces the lower wall 302. Facing.

As shown in FIGS. 1A and 1B, a pair of rail portions 11 and 11 projecting outward in the radial direction are provided side by side in the axial direction on the outer peripheral portion of the main body ring 1. The pair of rail portions 11 and 11 are formed by raising the outer peripheral surface S1 radially outward. Hereinafter, when the pair of rail portions 11 and 11 are described separately, the upper rail portion 11 is referred to as a rail portion 11U, and the lower rail portion 11 is referred to as a rail portion 11D. The pair of rail portions 11 and 11 are formed in an annular shape around the axis of the main body ring 1. The outer peripheral end faces S11U and S11D of the pair of rail portions 11U and 11D form the outermost portion in the radial direction on the outer peripheral surface S1 and are in sliding contact with the inner wall surface 10a of the cylinder 10. In this example, the vertical widths (thickness in the axial direction) of the pair of rail portions 11U and 11D are the same, but in the present invention, the vertical widths of the pair of rail portions may be different. Further, when the diameter of the main body ring 1 is reduced to the inner diameter of the cylinder 10 (that is, the diameter of the inner wall surface 10a of the cylinder 10) with only the main body ring 1 to which the coil expander 2 is not mounted, a pair of rail portions. The main body ring 1 may be formed so that a step in the radial direction is generated on the outer peripheral end faces S11U and S11D of the 11U and 11D. That is, one rail portion 11 may project radially outward from the other rail portion 11 in a state where the main body ring 1 is not urged by the coil expander 2. In that case, in the used state in which the coil expander 2 is attached, the main body ring 1 is twisted by the urging force of the coil expander 2, so that the pair of rail portions 11U and 11D are in sliding contact with the inner wall surface 10a of the cylinder, and a step is formed. Is resolved. Further, as shown in FIGS. 1A and 1B, an outer peripheral groove 12 recessed inward in the radial direction is formed between the pair of rail portions 11 and 11. The outer peripheral groove 12 extends along the circumferential length direction of the main body ring 1. The groove bottom surface indicated by the reference numeral S12 in FIG. 1 is a portion of the outer peripheral surface S1 that constitutes the bottom surface of the outer peripheral groove 12.

As shown in FIGS. 1A and 1B, the main body ring 1 is formed with a window hole V1 that radially penetrates from the outer peripheral surface S1 to the inner peripheral surface S2. Here, FIG. 3 is a perspective view showing a part of the main body ring 1. Reference numeral S5 in FIG. 3 indicates the end face of the abutment. As shown in FIG. 3, a plurality of window holes V1 are formed in the main body ring 1 so as to be arranged at equal intervals in the circumferential length direction. As shown in FIG. 2A, the window hole V1 is formed as a substantially rectangular through hole. The inner wall surface forming the window hole V1 includes an upper wall W1 and a lower wall W2 that are orthogonal to each other in the axial direction and face each other. The upper wall W1 and the lower wall W2 are parallel to each other, and the upper wall W1 is provided above the lower wall W2. The upper wall W1 and the lower wall W2 do not necessarily have to be parallel. As shown in FIGS. 2A and 2B, the opening on the outer peripheral surface S1 side of the window hole V1 is referred to as the outer peripheral opening V11, and the opening on the inner peripheral surface S2 side is referred to as the inner peripheral opening V12.

As shown in FIGS. 1A and 1B, the outer peripheral opening V11 is formed on the groove bottom surface S12. As a result, the window hole V1 is connected to the outer peripheral groove 12, which is a space formed between the pair of rail portions 11, 11. The pair of rail portions 11U, 11D slide on the inner wall surface 10a of the cylinder 10 on the outer peripheral end faces S11U, S11D, so that excess oil adhering to the inner wall surface 10a is scraped off to the oil pan (not shown) on the crank chamber side. Is done. As a result, the outflow of oil to the combustion chamber side (oil rise) is suppressed, the amount of oil is adjusted so that the lubricating oil film is appropriately held on the inner wall surface of the cylinder, and the piston 20 seizes with the operation of the internal combustion engine 100. Is prevented. At this time, the oil scraped off by the lower rail portion 11D is dropped into the oil pan through the piston gap PC1. On the other hand, the oil scraped off by the upper rail portion 11U temporarily stays in the outer peripheral groove 12, flows into the window hole V1 from the outer peripheral opening V11, and is discharged from the inner peripheral opening V12 to the inner peripheral side of the main body ring 1. It is dropped into an oil pan through the drain hole 304.

As shown in FIGS. 1A and 1B, a part of the inner peripheral surface S2 of the main body ring 1 forms a holding portion H1 for holding the coil expander 2. A groove recessed outward in the radial direction is formed by the holding portion H1, and the coil expander 2 is housed in the groove. The details of the holding portion H1 will be described later.

The coil expander 2 is formed by further forming a coil spring made of a wire rod made of steel or the like spirally wound in an annular shape. The wire rod forming the coil expander 2 has a circular or rectangular cross-sectional shape, but is not particularly limited. The coil expander 2 is mounted in the ring groove 30 so as to generate an expanding force in the radial direction thereof in the used state. The expanding force of the coil expander 2 urges (presses) the main body ring 1 outward in the radial direction. As a result, the outer peripheral end faces S11U, S11D of the pair of rail portions 11U, 11D of the main body ring 1 are pressed against the inner wall surface 10a of the cylinder 10, and the oil scraping function is exhibited.

FIG. 4 is a cross-sectional view of the oil ring 40 when the coil expander 2 is in the first posture. FIG. 4 shows a cross section orthogonal to the peripheral length direction of the main body ring 1 and including the window hole V1 in which the wire rod constituting the coil expander 2 is located at the outermost position in the radial direction of the coil expander 2. .. Here, as shown in FIG. 4, the vertical center of the inner peripheral opening V12 of the window hole V1 in the cross section orthogonal to the peripheral length direction is set as the opening center C1, and a straight line extending in the radial direction of the main body ring 1 through the opening center C1 is drawn. The opening center line CL1 is used. In the main body ring 1 of this example, since the upper wall W1 and the lower wall W2 of the window hole V1 are parallel to each other, the opening center line CL1 is the same as the center line of the vertical width of the window hole V1. Further, in this example, since the window hole V1 is formed at the center position above and below the main body ring 1, the opening center C1 is the same as the upper and lower center of the inner peripheral surface S2 of the main body ring 1, and the opening center line CL1 is It is also the same as the center line of the vertical width of the main body ring 1. Further, the upper edge of the inner peripheral opening V12 of the window hole V1 is referred to as an upper edge E1, and the lower edge is referred to as a lower edge E2. As shown in FIG. 4, each of the pair of rail portions 11 and 11 is provided so as to be located on opposite sides of the opening center C1 in the axial direction of the main body ring 1. Further, in the cross section orthogonal to the peripheral length direction and including the window hole V1, the straight line extending in the radial direction through the upper edge E1 in the inner peripheral opening V12 is defined as the first straight line L1, and the straight line extending in the radial direction through the lower edge E2 is the first straight line. Two straight lines L2. Further, the region sandwiched between the first straight line L1 and the second straight line L2 is referred to as the first region VA1.

As shown in FIG. 4, the center of the spiral of the coil expander 2 in the cross section orthogonal to the circumferential length direction of the main body ring 1, that is, the central axis of the coil spring forming the coil expander 2 is defined as the coil center C2 and the coil center. The straight line passing through C2 and extending in the radial direction of the coil expander 2 is defined as the coil center line CL2. Further, the portion of the surface of the coil expander 2 facing the radial outer side of the coil expander 2 is referred to as the outer peripheral surface 21 of the coil expander 2. Further, the intersection of the coil center line CL2 and the outer peripheral surface 21 of the coil expander 2 in the cross section orthogonal to the peripheral length direction is defined as the outer peripheral point P1. The outer peripheral point P1 is the outermost end in the radial direction of the coil expander 2. Further, reference numeral E21 in FIG. 4 indicates an upper end portion of the coil expander 2, and reference numeral E22 indicates a lower end portion of the coil expander 2.

As shown in FIG. 4, when the coil expander 2 is in the first posture, the coil center C2 is larger than the opening center C1 of the window hole V1 in the cross section including the window hole V1 orthogonal to the circumferential length direction of the main body ring 1. It is located on the upper side. Further, the lower end portion E22 of the coil expander 2 is located above the second straight line L2. That is, the coil expander 2 is located above the second straight line L2. Further, when the coil expander 2 is in the first posture, the outer peripheral point P1 of the coil expander 2 is in contact with a portion of the inner peripheral surface S2 of the main body ring 1 above the opening center C1. The point where the coil expander 2 abuts on the outer peripheral point P1 in the first posture on the inner peripheral surface S2 of the main body ring 1 is defined as the first contact point CP1. As shown in FIG. 4, the coil diameter D1 of the coil expander 2 is larger than the vertical width (width in the axial direction) d1 of the inner peripheral opening V12 of the window hole V1.

FIG. 5 is a cross-sectional view of the oil ring 40 when the coil expander 2 is in the second posture. FIG. 5 shows a cross section at the same position as in FIG. As shown in FIG. 5, when the coil expander 2 is in the second posture, the coil center C2 is larger than the opening center C1 of the window hole V1 in the cross section including the window hole V1 orthogonal to the circumferential length direction of the main body ring 1. It is located on the lower side. Further, the upper end portion E21 of the coil expander 2 is located below the first straight line L1. That is, the coil expander 2 is located below the first straight line L1. Further, when the coil expander 2 is in the second posture, the outer peripheral point P1 of the coil expander 2 is in contact with a portion of the inner peripheral surface S2 of the main body ring 1 below the opening center C1. The point where the coil expander 2 abuts on the outer peripheral point P1 in the second posture on the inner peripheral surface S2 of the main body ring 1 is defined as the second contact point CP2.

The holding portion H1 allows the coil expander 2 to move relative to the main body ring 1 in the axial direction within a predetermined range, so that the coil expander 2 takes a posture between the first posture and the second posture. Hold the coil expander 2 so that it can be changed. The coil expander 2 moves from the first posture to the second posture by moving downward along the axial direction of the main body ring 1, and moves from the second posture to the first posture by moving to the upper side. To reach. As shown in FIGS. 4 and 5, the holding portion H1 is formed by a part of the inner peripheral surface S2 of the main body ring 1 including an upper contact surface H11, a lower contact surface H12, and a connection surface H13. ing. The upper contact surface H11 and the lower contact surface H12 extend in the radial direction and face each other with a predetermined interval in the vertical direction. As shown in FIG. 4, when the coil expander 2 is in the first posture, the upper contact surface H11 is in contact with the coil expander 2 from above. As a result, the coil expander 2 in the first posture is restricted from moving upward. Further, as shown in FIG. 5, when the coil expander 2 is in the second posture, the lower contact surface H12 abuts on the coil expander 2 from the lower side. As a result, the coil expander 2 in the second posture is restricted from moving downward. Here, the radial outer edge of the upper contact surface H11 is referred to as the outer peripheral edge HE1, and the radial outer edge of the lower contact surface H12 is referred to as the outer peripheral edge HE2. The connection surface H13 connects the outer peripheral edge HE1 of the upper contact surface H11 and the outer peripheral edge HE2 of the lower contact surface H12, and includes the first contact point CP1 and the second contact point CP2 along the axial direction. It is extending.

The upward movement of the coil expander 2 in the first posture is restricted by the upper contact surface H11, and the downward movement of the coil expander 2 in the second posture is restricted by the lower contact surface H12. Since the connection surface H13 connecting the upper contact surface H11 and the lower contact surface H12 extends along the axial direction, the coil expander 2 takes the first posture while sliding on the connection surface H13. It is possible to move along the axial direction between the second postures. The coil expander 2 slides on the connection surface H13 in a state where the contact between the outer peripheral point P1 and the connection surface H13 is maintained by its self-tension. Therefore, even while the coil expander 2 is moving between the first posture and the second posture, the main body ring 1 is urged outward in the radial direction by the coil expander 2, and the rail portions 11 and 11 are urged. A surface pressure is applied to the inner wall surface 10a of the cylinder 10.

When the internal combustion engine 100 provided with the oil ring 40 according to the present embodiment is operated, the coil expander 2 moves downward due to inertial force in the process in which the descending piston 20 reaches the bottom dead center from the center of the stroke. This leads to the second posture as shown in FIG. Further, in the process in which the ascending piston 20 reaches the top dead center from the central portion of the stroke, the coil expander 2 moves upward due to the inertial force to reach the first posture as shown in FIG. That is, the oil ring 40 is configured so that the coil expander 2 moves in the same direction as the movement direction (stroke direction) of the piston 20 in the reciprocating motion of the piston 20.

[Action / Effect]
As described above, in the oil ring 40 according to the present embodiment, the holding portion H1 allows the coil expander 2 to move along the axial direction of the main body ring 1, so that the coil expander 2 has the first posture and the first posture. The posture can be changed between the two postures. When the coil expander 2 is in the first posture, the coil center C2 is located above the opening center C1 in the cross section including the window hole V1 orthogonal to the circumferential length direction of the main body ring 1, and the coil expander 2 is located. Is located above the second straight line L2, and when the coil expander 2 is in the second posture, the coil center C2 is located below the opening center C1 in the cross section and the coil expander 2 is located. It is located below the first straight line L1.

Here, if the coil expander is held in a state where the opening center of the inner peripheral opening of the window hole and the coil center of the coil expander are aligned in the axial direction, the oil from the inner peripheral opening of the window hole is held. Discharge may be hindered by the coil expander and oil may stay in the window holes for a long period of time. In such a case, the oil deteriorates and the deposit is accumulated in the window hole, which further hinders the oil discharge from the inner peripheral opening, reduces the effect of reducing the hydraulic pressure between the rail parts by the window hole, and the oil scraping ability of the rail part. There is a concern that this will lead to a decline in oil pressure.

On the other hand, in the oil ring 40 according to the present embodiment, the coil expander is used between the first posture in which the coil center C2 is displaced upward with respect to the opening center C1 and the second posture in which the coil center C2 is displaced downward. The holding portion H1 allows the coil expander 2 to move along the axial direction of the main body ring 1 so that the 2 can change its posture. Therefore, the coil expander 2 reciprocates between the first posture and the second posture so as to be interlocked with the reciprocating motion of the piston 20 by the inertial force acting during the operation of the internal combustion engine 100, and repeatedly changes the posture. .. By doing so, it is possible to shorten the period in which the positions of the coil center C2 and the opening center C1 in the axial direction coincide with each other during the operation of the internal combustion engine 100, and the oil can be smoothly discharged from the inner peripheral opening V12. As a result, the fluidity of the oil in the window hole V1 is improved, and the accumulation of deposits can be suppressed. By suppressing the accumulation of deposits, the oil existing in the outer peripheral groove 12 formed between the pair of rail portions 11 and 11 flows through the window hole V1 and is quickly discharged to the inner peripheral side of the main body ring 1. Will be. As a result, it is possible to suppress a decrease in the oil scraping ability of the pair of rail portions 11, 11. Further, the coil expander 2 is held by the holding portion H1 so as to be located above the second straight line L2 in the first posture and below the first straight line L1 in the second posture. Has been done. According to this, as shown in FIGS. 4 and 5, when the coil expander 2 is in the first posture and the second posture, at least a part of the inner peripheral opening V12 of the window hole V1 is covered by the coil expander 2. It will be in an unbroken state. Therefore, the oil can be discharged more smoothly from the inner peripheral opening V12.

Further, the holding portion H1 has an upper contact surface H11 that comes into contact with the coil expander 2 in the first posture from above and a lower side that comes into contact with the coil expander 2 in the second posture from below. It includes a side contact surface H12, a connection surface H13 that connects the outer peripheral edges of the upper contact surface H11 and the lower contact surface H12, and extends in the axial direction of the main body ring 1. As a result, the coil expander 2 can move along the axial direction between the first posture and the second posture.

Further, as shown in FIGS. 4 and 5, in the oil ring 40 according to the present embodiment, the peripheral length of the main body ring 1 is obtained both when the coil expander 2 is in the first posture and when the coil expander 2 is in the second posture. The coil center C2 is located outside the first region VA1 in a cross section orthogonal to the direction and including the window hole V1. As a result, oil can be discharged more smoothly from the inner peripheral opening V12, and deposit accumulation can be suppressed more reliably. As a result, it is possible to further suppress a decrease in the oil scraping ability of the pair of rail portions 11, 11. In the present invention, the coil center may be located outside the first region in either the first posture or the second posture. By doing so, the fluidity of the oil in the window hole can be improved.

Further, at least one of a resin coating, a nitriding treatment coating, a chrome plating treatment coating, a PVD treatment coating, and a DLC treatment coating is provided on at least one of the inner peripheral surface S2 of the main body ring 1 and the outer peripheral surface 21 of the coil expander 2. A hard coating containing only one layer may be formed. The "resin film" refers to a film formed of a resin material. Further, the "nitriding treatment film" refers to a film formed by infiltrating nitrogen into the metal surface by nitriding treatment. Further, the "chrome-plated coating" refers to a coating formed by chrome plating. Chromium plating is also called industrial chrome plating. Further, the "PVD (physical vapor deposition) treated coating film" refers to a coating film formed by the PVD method. PVD
The method is a kind of vapor deposition method for forming a film by adhering particles emitted from a target to the surface of a substance, and is also called physical vapor deposition. The PVD method can include an ion plating method, a vacuum vapor deposition method, an ion beam vapor deposition method, a sputtering method, an FCVA (Filtered Cathodic Vacuum Arc) method and the like. In addition, "DLC (Diamond Like Carbon) treated coating"
Refers to an amorphous hard carbon film mainly composed of hydrocarbons and allotropes of carbon. By forming such a hard coating, the wear resistance of the inner peripheral surface S2 of the main body ring or the outer peripheral surface 21 of the coil expander 2 is enhanced, and the slidability of the coil expander 2 with respect to the main body ring 1 is improved. Can be done.

[Modification example]
Hereinafter, the combined oil ring according to the modified example of the embodiment will be described. In the description of the combined oil ring 40A (hereinafter referred to as the oil ring 40A) according to the following modification, the differences from the oil ring 40 described with reference to FIGS. 1 to 5 will be mainly described, and the same points as the oil ring 40 will be described. I will omit the detailed explanation. FIG. 6 is a cross-sectional view of the oil ring 40A when the coil expander 2 is in the first posture. Further, FIG. 7 is a cross-sectional view of the oil ring 40A when the coil expander 2 is in the second posture.

As shown in FIGS. 6 and 7, in the oil ring 40A according to the first modification, the holding portion H1 allows the coil expander 2 to move along the axial direction of the main body ring 1, so that the coil expander 2 becomes the first. The posture can be changed between the first posture and the second posture. When the coil expander 2 is in the first posture, the coil center C2 is located above the opening center C1 in the cross section including the window hole V1 orthogonal to the circumferential length direction of the main body ring 1, and the coil expander 2 is located. Is located above the first straight line L1 and the coil expander 2 is in the second posture, the coil center C2 is located below the opening center C1 in the cross section and the coil expander 2 is the second. It is located below the straight line L2.

The same effect as that of the oil ring 40 can be obtained in the oil ring 40A according to the first modification. That is, by repeatedly changing the posture between the first posture and the second posture so that the coil expander 2 is interlocked with the reciprocating motion of the piston 20, the coil center C2 and the opening center during the operation of the internal combustion engine 100 The period in which the positions of C1 in the axial direction match can be shortened. As a result, oil can be smoothly discharged from the inner peripheral opening V12. As a result, also in the oil ring 40A according to the modified example 1, the oil existing in the outer peripheral groove 12 is quickly discharged to the inner peripheral side of the main body ring 1 as in the oil ring 40, and the pair of rail portions 11 and 11 It is possible to suppress a decrease in oil scraping ability.

Further, as shown in FIGS. 6 and 7, in the modified example, the coil expander 2 is orthogonal to the circumferential length direction of the main body ring 1 in both the first posture and the second posture, and is a window hole. In the cross section including V1, the coil expander 2 is located outside the first region VA1. That is, the coil expander 2 is arranged so as not to overlap the inner peripheral opening V12 in the radial direction of the main body ring 1 in the first posture and the second posture. As a result, the oil can be discharged from the inner peripheral opening V12 more smoothly, the fluidity of the oil in the window hole V1 is further improved, and the accumulation of deposits can be suppressed more reliably. As a result, it is possible to further suppress a decrease in the oil scraping ability of the pair of rail portions 11, 11. In the present invention, the coil expander may be located outside the first region in either the first posture or the second posture. By doing so, the fluidity of the oil in the window hole can be improved.

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

100: Internal combustion engine 10: Cylinder 20: Piston 30: Ring groove 40, 40A: Combination oil ring 1: Main body ring 11: Rail part 2: Coil expander V1: Window hole H1: Holding part C1: Opening center C2: Coil center

Claims (6)

An oil ring attached to the piston of an internal combustion engine.
A coil expander formed in an annular shape by a spirally wound wire rod and arranged in an annular shape on the inner peripheral side of the main body ring to urge the main body ring radially outward. Equipped with
A pair of rail portions, which are formed in an annular shape around the axis of the main body ring and project outward in the radial direction of the main body ring, are provided on the outer peripheral portion of the main body ring side by side in the axial direction of the main body ring.
The main body ring is formed with a window hole that penetrates radially from the outer peripheral surface to the inner peripheral surface and connects to the space between the pair of rail portions.
A part of the inner peripheral surface forms a holding portion for holding the coil expander, and forms a holding portion.
By allowing the holding portion to move the coil expander along the axial direction of the main body ring, the coil expander is orthogonal to the peripheral length direction of the main body ring and has the coil extract in a cross section including the window hole. The center of the coil, which is the center of the spiral of the panda, is the center of the inner peripheral opening, which is the opening on the inner peripheral surface side of the window hole. Between the first posture located on the upper side and the second posture in which the coil center is located on the lower side of the internal combustion engine in the axial direction with respect to the opening center in the cross section. The posture can be changed,
When the coil expander is in the second posture, the holding portion is orthogonal to the circumferential length direction of the main body ring and passes through the upper edge of the inner peripheral opening in the cross section including the window hole, and the diameter of the main body ring. When the coil expander is located below the first straight line extending in the direction and the coil expander is in the first posture, the main body passes through the lower edge of the inner peripheral opening in the cross section. The coil expander is held so that the coil expander is located above the second straight line extending in the radial direction of the ring.
Combination oil ring. The holding portion is the first in a cross section including the window hole orthogonal to the circumferential length direction of the main body ring at least one of the coil centers in the first posture and the second posture. The coil expander is held so that the center of the coil is located outside the first region sandwiched between the straight line and the second straight line.
The combination oil ring according to claim 1. The holding portion is the first in a cross section including the window hole orthogonal to the circumferential length direction of the main body ring at least one of the first posture and the second posture of the coil expander. The coil expander is held so that the coil expander is located outside the first region sandwiched between the first straight line and the second straight line.
The combination oil ring according to claim 1 or 2. The holding portion is the first in a cross section including the window hole, which is orthogonal to the peripheral length direction of the main body ring in both the first posture and the second posture of the coil expander. The coil expander is held so that the coil expander is located outside the region.
The combination oil ring according to claim 3. The holding portion has an upper contact surface that comes into contact with the coil expander from above when the coil expander is in the first posture, and the coil when the coil expander is in the second posture. A lower contact surface that contacts the expander from below, a radial outer edge of the body ring on the upper contact surface, and a radial outer edge of the body ring on the lower contact surface. Includes a connecting surface that extends axially along with the body ring.
The combination oil ring according to any one of claims 1 to 4. At least one of a resin film, a nitrided film, a plated film, a PVD-treated film, and a DLC-treated film is layered on at least one of the inner peripheral surface of the main body ring and the outer peripheral surface of the coil expander. A hard coating is formed, including
The combination oil ring according to any one of claims 1 to 5.

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