WO2019142668A1

WO2019142668A1 - Oil ring

Info

Publication number: WO2019142668A1
Application number: PCT/JP2019/000071
Authority: WO
Inventors: 嘉夫岡田; 充洋安達
Original assignee: 株式会社リケン
Priority date: 2018-01-22
Filing date: 2019-01-07
Publication date: 2019-07-25
Also published as: JP7053282B2; JP2019127962A

Abstract

An oil ring 1 has an oil ring body 10 provided with a land 30 protruding diametrally outward, and a coil expander 20 that is mounted on a diametrally inward portion of the oil ring body and that biases the oil ring body diametrally outward. The land 30 has an upper surface 31 facing one way in an axial direction, an outermost circumferential surface 34 that comprises a cylindrical surface parallel to the axial direction and that faces diametrally outward at the diametrally farthest outward side, and a tapered surface 33 comprising part of a conical surface that diametrally expands from one axial side toward the other axial side, the tapered surface 33 being positioned between the upper surface 31 and the outermost circumferential surface 34. The angle that the tapered surface 33 forms with the axial direction is greater than 17° and less than 27°.

Description

Oil ring

The present invention relates to an oil ring used for a piston of a reciprocating engine (reciprocating internal combustion engine), and more particularly to a two-piece type combined oil ring in which a coil expander is mounted on a radially inner portion of the oil ring body.

Conventionally, in addition to a compression ring for sealing combustion gas, an oil ring for sealing lubricating oil is attached to a piston of a reciprocating engine.

Oil rings are classified into three-piece oil rings mainly used for gasoline engines and two-piece oil rings mainly used for diesel engines. Due to demands for lower fuel consumption and the like, a two-piece oil ring capable of further reducing the axial width has also come to be used in gasoline engines.

As such a two-piece type oil ring, an oil ring main body having a web portion having an oil passing hole and a pair of rail portions integrally provided on both sides (upper and lower) in the axial direction of the web portion; 2. Description of the Related Art A coil expander is known which is mounted on a radially inner portion of a main body to urge the oil ring main body outward in the radial direction. In such a two-piece type oil ring, the oil ring main body is formed in a split ring shape having a joint, and can be expanded (diameter increase) by being urged radially outward by a coil expander. It has become. Then, the oil ring main body is biased and expanded by the coil expander, and the outer peripheral surface of each rail portion facing radially outward contacts the inner peripheral surface of the cylinder with a constant contact pressure (surface pressure), whereby the piston When reciprocated, the oil accumulated between the pair of rails is applied to the inner peripheral surface of the cylinder and the excess oil is scraped down by the rails and returned to the crank chamber through the oil passing hole. Form an oil film of appropriate thickness.

In recent years, with the improvement of engine performance by internal combustion engine due to market demand such as low fuel consumption and low oil consumption, the oil ring also suppresses the oil raking action at the piston rising stroke, and the oil raking action at the piston descent process There is a demand for a product having the ability to reduce the oil consumption while reducing the friction against the inner circumferential surface of the cylinder. In order to meet such requirements, oil rings have been proposed in which the outer peripheral surface facing the radially outer side has various shapes.

For example, in Patent Document 1, the outer peripheral surface of the upper and lower rail portions is disposed on the sliding surface sliding on the inner peripheral surface of the cylinder and on the combustion chamber side (upper surface side of the oil ring) of the sliding surface. An oil ring is described that is configured to have a tapered surface that gradually reduces in diameter toward the side.

Unexamined-Japanese-Patent No. 9-144881

By providing a tapered surface as in the oil ring described in Patent Document 1, it is possible to reduce the area of the sliding surface sliding on the inner circumferential surface of the cylinder. As a result, the contact surface pressure applied to the inner peripheral surface of the cylinder by the sliding surface is increased, and the action of scraping oil at the time of the piston downstroke is obtained. Further, at the time of the piston upstroke, an oil film is formed between the tapered surface and the inner circumferential surface of the cylinder, and the sliding surface runs on the oil film, whereby the oil is prevented from being scooped up. Thus, it is known that an oil ring provided with a tapered surface like the oil ring described in Patent Document 1 is effective for reducing the amount of oil consumption.

By the way, there is a process of inserting a piston equipped with an oil ring into a cylinder as one process of engine assembly. In the process, the piston is usually inserted into the cylinder from the skirt side (lower side) of the piston. On the other hand, for example, in a large diesel engine or the like, the piston may be inserted into the cylinder from the crown side (upper side) of the piston.

When the piston is inserted into the cylinder from the upper end side of the liner forming the inner circumferential surface of the cylinder, that is, when the piston is inserted into the cylinder from the lower side of the piston, the oil ring is inserted into the cylinder from the lower surface side Be done. At this time, if the oil ring provided with the above-described tapered surface is used, the sliding surface is inserted earlier than the tapered surface. When the sliding surface contacts the inner circumferential surface of the cylinder, the entire sliding surface is pressed against the inner circumferential surface of the cylinder by the bias from the coil expander, and the axial direction of the oil ring matches the axial direction of the cylinder It becomes stable and is inserted while maintaining that state. Therefore, the oil ring can be stably incorporated into the engine.

On the other hand, when the piston is inserted into the cylinder from the lower end side of the liner, that is, when the piston is inserted into the cylinder from the upper side of the piston, the oil ring is inserted into the cylinder from the upper surface side. At this time, if the oil ring provided with the above-described tapered surface is used, the tapered surface is inserted earlier than the sliding surface. Here, since the diameter of the tapered surface is smaller than that of the sliding surface, the tapered surface is usually inserted without contacting the inner circumferential surface of the cylinder between the insertion of the tapered surface and the insertion of the sliding surface. It will be done. At this time, since the position of the oil ring is unstable in the radial direction with respect to the cylinder, the tapered surface may come in contact with the inner peripheral surface of the cylinder and damage such as a part of the oil ring may occur. is there. In addition, if the piston is forced into the cylinder while the axial direction of the oil ring and the axial direction of the cylinder do not match, the oil ring may be deformed. This problem is particularly pronounced in large diesel engines where the weight of the piston and connecting rod is relatively large.

An object of the present invention is to solve such a point, and it is an object of the present invention to provide an oil ring capable of reducing the possibility of damage at the time of engine assembly while reducing oil consumption. is there.

The oil ring of the present invention is mounted on an oil ring main body provided with lands projecting radially outward, and mounted on a radially inner portion of the oil ring main body, with the oil ring main body directed radially outward. An oil ring having a coil expander for biasing, wherein the land comprises an upper surface facing in one axial direction and a cylindrical surface parallel to the axial direction, and an outermost periphery facing radially outward at an outermost side in the radial direction A portion of a conical surface which is enlarged in diameter from the one side in the axial direction to the other side in the axial direction, and has a tapered surface located between the upper surface and the outermost peripheral surface; An angle formed by the tapered surface with respect to the axial direction is more than 17 ° and less than 27 °.

In the configuration described above, the upper surface is linear in a sectional view along a plane including the central axis of the oil ring, and in the sectional view, a straight line along the upper surface and a straight line along the outermost circumferential surface And the end of the outermost side of the outermost peripheral surface is the upper end of the outermost peripheral surface, and the other end of the outermost peripheral surface is the lower end of the outermost peripheral surface. The ratio of the distance from the upper end to the lower end to the distance from the one point to the lower end is preferably 0.76 or less.

Still preferably, in the above-described configuration, the distance from the first point to the lower end is greater than 0.15 mm and less than or equal to 0.30 mm in the configuration described above.

In the above configuration, when the intersection of the straight line along the upper surface and the straight line along the tapered surface is a second point in the above configuration, the outermost circumferential surface is radially outward from the second point Preferably, it protrudes by 0.015 mm or more.

Still preferably, in the above-described configuration, the distance from the upper end to the lower end is 0.15 mm or less in the above configuration.

In the present invention, in the above-described configuration, it is preferable that the surface roughness of the tapered surface is larger than the surface roughness of the outermost peripheral surface.

In the configuration described above, the upper surface is linear in a cross-sectional view along a plane including the central axis of the oil ring, and the land is connected to the upper surface radially inward and radially outward And further includes a first curved surface curved to be convex on the surface side continuous with the tapered surface, the first curved surface being a straight line along the upper surface and a straight line along the tapered surface in the sectional view It is preferable not to cross any of the above.

Still preferably, in a configuration according to the present invention, the first curved surface has an arc shape whose radius is 0.005 mm or more in the sectional view.

In the configuration described above, the upper surface is linear in a cross-sectional view along a plane including the central axis of the oil ring, and the land is connected to the tapered surface radially inward and in the radial direction It further has a second curved surface which is curved to be convex on the surface side and is continuous with the outermost peripheral surface outside, and the second curved surface is a straight line along the tapered surface and the outermost periphery in the sectional view It is preferred not to intersect any of the straight lines along the surface.

Still preferably, in a configuration according to the present invention, the second curved surface has an arc shape whose radius is 0.005 mm or more in the sectional view.

In the present invention according to the above-mentioned configuration, the width along the axial direction of the oil ring main body is preferably 2.5 mm or more.

Still preferably, in a configuration according to the present invention, the outermost circumferential surface is a surface of a hard coating layer constituting a surface layer of the land.

ADVANTAGE OF THE INVENTION According to this invention, the oil ring which can reduce the possibility of the damage at the time of engine assembly can be provided, reducing oil consumption.

It is a top view of the oil ring as one embodiment of the present invention. It is front sectional drawing which shows the use condition of the oil ring shown in FIG. It is front sectional drawing which expands and shows the land part of the oil ring shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same reference numeral is given to the same configuration in each drawing. In the present specification, the axial direction means a direction along the central axis O (see FIG. 1) of the oil ring 1. Further, one side in the axial direction means the combustion chamber side (upper side in FIGS. 2 and 3) in the use state of the oil ring 1. Further, the other side in the axial direction is the opposite side to the one side in the axial direction, and means the crank chamber side (lower side in FIGS. 2 and 3) in the used state of the oil ring 1.

FIG. 1 is a plan view of an oil ring 1 according to an embodiment of the present invention. The oil ring 1 shown in FIG. 1 is also called an oil control ring. The oil ring 1 is mounted and used, for example, in a ring groove formed on the outer peripheral surface of a piston of a diesel engine. The oil ring 1 is a two-piece type, and includes an oil ring main body 10 and a coil expander 20.

As shown in FIG. 1, the oil ring main body 10 is formed in a split ring shape provided with a joint 10a. That is, the oil ring main body 10 is formed in a C-shape in which a part in the circumferential direction is cut and the cut portion becomes the joint 10a. The oil ring main body 10 can be made of, for example, steel (steel material). The oil ring main body 10 can be elastically deformed in the radial direction by forming the joint portion 10 a and causing the joint portion 10 a to approach and separate in the circumferential direction. In addition, when the oil ring main body 10 is disposed in the cylinder C (see FIG. 2) in a state of being attached to the piston P (see FIG. 2), the joint portion 10a becomes a substantially annular shape closed and the coil expander 20 is biased radially outward. As a result, the oil ring main body 10 and the inner circumferential surface 101 (see FIG. 2) of the cylinder C (see FIG. 2) are in close contact over the entire circumference of the piston P, and oil can be sealed.

FIG. 2 is a front sectional view showing the usage state of the oil ring 1. In detail, FIG. 2 is a cross-sectional view along a plane including the central axis O (see FIG. 1) of the oil ring 1, and this is the same as FIG. As shown in FIG. 2, the oil ring main body 10 has a web portion 11 and a pair of rail portions 12, and the cross section thereof is substantially M-shaped.

The web portion 11 is formed in a thin cylindrical shape, and at the central position in the axial direction, a plurality of oil passing holes 13 penetrating the web portion 11 in the radial direction are provided side by side at intervals in the circumferential direction . These oil passing holes 13 can be formed, for example, in a long hole or a circular hole.

The pair of rail portions 12 is provided integrally with the web portion 11 on one side and the other side in the axial direction of the web portion 11 respectively. The radial thickness dimension of each rail portion 12 is larger than the radial thickness dimension of the web portion 11, and the web portion 11 is connected to the rail portion 12 at the radial intermediate portion of each rail portion 12. There is.

A mounting groove 14 for mounting the coil expander 20 is provided on a radially inner portion (inner peripheral surface) of the oil ring main body 10. The mounting groove 14 has a semicircular concave cross section which extends from the web portion 11 to both the rail portions 12 and extends along the circumferential direction all around the oil ring main body 10.

Although it simplifies and shows in FIG. 1, the coil expander 20 connects the both ends, and what was wound and formed in the ring shape what wound the wire formed by steel materials etc. in coil shape is comprised. The coil expander 20 is elastically deformable in the radially inward and outward directions, and the outer diameter in its natural state is larger than the inner diameter of the oil ring main body 10. Then, as shown in FIG. 2, the coil expander 20 is mounted in the mounting groove 14 of the oil ring main body 10 in a state of being elastically deformed in the diameter reducing direction, and biases the oil ring main body 10 radially outward.

As shown in FIG. 2, the radius viewed from the direction perpendicular to the circumferential direction of the coil expander 20 is slightly smaller than the radius of the mounting groove 14 of the oil ring main body 10.

Lands 30 are integrally provided on outer peripheral ends of the pair of rail portions 12 facing radially outward. Each of the lands 30 constitutes an outer peripheral end of the corresponding rail portion 12 that protrudes radially outward over the entire circumference.

Next, the details of the lands 30 will be described based on FIG. FIG. 3 is a front sectional view showing the land 30 of the oil ring 1 in an enlarged manner. Since the lands 30 provided on the upper rail portion 12 and the lands 30 provided on the lower rail portion 12 basically have the same shape, they are provided on the upper rail portion 12 in the following. A description will be given based on the land 30.

As shown in FIG. 3, the outer wall of the land 30 has an upper surface 31, a lower surface 32, an outermost peripheral surface 34, and a tapered surface 33.

The upper surface 31 of the land 30 is a surface that faces one side in the axial direction. In the present embodiment, the upper surface 31 is linear in a cross-sectional view shown in FIG. In the example shown in FIG. 3, the upper surface 31 is a part of a conical surface whose diameter gradually increases from one side in the axial direction toward the other side in the axial direction.

The lower surface 32 of the land 30 is a surface facing the other side in the axial direction. In the present embodiment, the lower surface 32 is linear in a cross sectional view shown in FIG. In the example shown in FIG. 3, the lower surface 32 is a part of a conical surface whose diameter gradually increases from the other side in the axial direction toward one side in the axial direction.

The outermost circumferential surface 34 is a surface which is located on the radially outermost side of the oil ring 1 and faces the radially outer side. The outermost circumferential surface 34 is a cylindrical surface parallel to the axial direction. The outermost circumferential surface 34 is located between the lower surface 32 and the tapered surface 33. More specifically, the outermost circumferential surface 34 is located between the lower surface 32 and the tapered surface 33 in the direction of the outer wall along the outer wall of the land 30 in the cross sectional view shown in FIG. 3. Hereinafter, one end of the outermost circumferential surface 34 is referred to as the upper end 41 of the outermost circumferential surface 34, and the other end of the outermost circumferential surface 34 is referred to as the lower end 42 of the outermost circumferential surface 34.

As shown in FIG. 3, the tapered surface 33 gradually expands in diameter from one side in the axial direction toward the other side in the axial direction. In other words, the tapered surface 33 is a part of a conical surface that is inclined with respect to the axial direction. The tapered surface 33 is located between the upper surface 31 and the outermost surface 34. More specifically, the tapered surface 33 is located between the upper surface 31 and the outermost surface 34 in the direction of the outer wall along the outer wall of the land 30 in the cross sectional view shown in FIG. 3. As shown in FIG. 3, the angle α formed by the tapered surface 33 with respect to the axial direction is smaller than the angle formed by the upper surface 31 with respect to the axial direction. Specifically, the angle α is more than 17 ° and less than 27 °. The step of inserting the piston P (see FIG. 2) equipped with the oil ring 1 as a step of assembling the engine into the cylinder C (see FIG. 2) as the angle α is more than 17 ° (It is described also at the time of assembly.), The tapered surface 33 is hard to contact the inner circumferential surface 101 (see FIG. 2) of the cylinder C, and the possibility of damage to the oil ring 1 can be reduced. Further, when the angle α is less than 27 °, an oil film is sufficiently formed between the tapered surface 33 and the inner peripheral surface 101 of the cylinder C during the upstroke of the piston P, and the outermost peripheral surface 34 is on the oil film. By riding up, it is suppressed that the oil is scraped up, so the amount of oil consumption can be reduced. From the viewpoint of enhancing the above effects, the angle α is preferably 18 ° or more and 26 ° or less.

An intersection point of a straight line along the upper surface 31 of the land 30 and a straight line along the outermost circumferential surface 34 in a cross-sectional view shown in FIG. Further, in the cross-sectional view shown in FIG. 3, the distance from the first point 43 to the lower end 42 of the outermost circumferential surface 34 is taken as a land width L. Moreover, let the distance from the upper end 41 of the outermost peripheral surface 34 to the lower end 42 be outermost peripheral surface width L1 in the cross sectional view shown in FIG. At this time, the ratio of the outermost circumferential surface width L1 to the land width L, that is, L1 / L is preferably 0.76 or less. When L1 / L is 0.76 or less, the area of the tapered surface 33 is sufficiently ensured, and the effect of reducing the oil consumption by providing the tapered surface 33 is maintained for a long time.

The land width L is preferably more than 0.15 mm and 0.30 mm or less. When the land width L is 0.15 mm or less, the rigidity of the lands 30 is insufficient, and the lands 30 are easily deformed during engine assembly.

An intersection point of a straight line along the upper surface 31 of the land 30 and a straight line along the tapered surface 33 in the cross-sectional view shown in FIG. Further, in a cross sectional view shown in FIG. 3, a distance by which the outermost circumferential surface 34 protrudes radially outward from the second point 44 is taken as a protrusion length H. At this time, the protrusion length H is preferably 0.015 mm or more. When the projection length H is 0.015 mm or more, the distance between the upper surface 31 and the inner peripheral surface 101 of the cylinder C can be sufficiently maintained, thereby reducing the possibility of damage to the oil ring 1 at the time of engine assembly. be able to.

The outermost circumferential surface width L1 is preferably 0.15 mm or less. When the outermost circumferential surface width L1 is 0.15 mm or less, the contact surface pressure applied to the inner circumferential surface 101 of the cylinder C by the outermost circumferential surface 34 is increased, and the action of scraping oil during the piston descending stroke is improved.

The surface roughness of the tapered surface 33 is preferably larger than the surface roughness of the outermost circumferential surface 34. By making the surface roughness of the tapered surface 33 larger than the surface roughness of the outermost circumferential surface 34, the oil is easily held in the recess formed in the tapered surface 33, and the oil flows to the combustion chamber side (upper side in FIG. 3). Scattering is suppressed. From the viewpoint of enhancing the above effects, the surface roughness of the tapered surface 33 is more preferably 2 μm or more and 10 μm or less. The surface roughness of the tapered surface 33 and the outermost circumferential surface 34 is the same as that of the oil ring 1 along the circumferential direction of the oil ring 1 in a state where the stylus is in contact with the surfaces of the tapered surface 33 and the outermost circumferential surface 34. It can measure by making it move relatively. Specifically, the surface roughness of the tapered surface 33 and the outermost surface 34 is a method described in JIS B 0601 2001 using a surface roughness / contour shape measuring machine (Surfcom 1800 D, manufactured by Tokyo Seimitsu Co., Ltd.) It can be measured based on As a measurement condition of surface roughness, a cutoff value of 0.8 mm, an evaluation length of 4.0 mm, a measurement speed of 0.3 mm / s, and a 60 ° conical stylus having a tip radius of 2 μm as a stylus. It can be used.

The width along the axial direction of the oil ring main body 10 (see FIG. 2) is preferably 2.5 mm or more. If the width along the axial direction of the oil ring main body 10 is 2.5 mm or more, the rigidity of the oil ring main body 10 does not easily decrease, and deformation during processing and engine assembly can be prevented. Furthermore, in the point which can exhibit the said effect more, it is more preferable that the width | variety in alignment with the axial direction of the oil ring main body 10 is 3.0 mm or more. Further, the ratio of the outermost circumferential surface width L1 to the width along the axial direction of the oil ring main body 10 is preferably 0.01 or more and 0.06 or less. If the ratio of the outermost circumferential surface width L1 to the width along the axial direction of the oil ring main body 10 is 0.01 or more and 0.06 or less, the oil scraping performance is more stabilized.

It is preferable that the surface layer on the outermost peripheral surface 34 side of the land 30 of the oil ring main body 10 be formed of a hard coating layer. That is, it is preferable that the outermost circumferential surface 34 be the surface of the hard coating layer that constitutes the surface layer of the land 30. As the hard coating layer, for example, a configuration provided with at least one of a nitriding treatment layer, a PVD treatment layer, a hard chromium plating treatment layer, and a DLC layer can be adopted. By providing such a hard coating layer, it is possible to prevent the disappearance of the outermost peripheral surface 34 due to wear over a long period of time, and reduce the oil consumption over a long period of time.

Note that "PVD-treated layer" means "layer formed by physical vapor deposition (Physical Vapor Deposition)", and "DLC (Diamond Like Carbon) layer" means a non-hydrocarbon or carbon allotrope mainly. Amorphous hard carbon film is meant.

As shown in FIG. 3, the outer wall of the land 30 further includes a first curved surface 35, a second curved surface 36, and a third curved surface 37.

The first curved surface 35 is continuous with the upper surface 31 of the land 30 radially inward and is continuous with the tapered surface 33 radially outward. The first curved surface 35 is a curved surface convex on the surface side, which smoothly connects the upper surface 31 and the tapered surface 33. The first curved surface 35 does not intersect either the straight line along the upper surface 31 or the straight line along the tapered surface 33 in a cross-sectional view shown in FIG. 3. As described above, by having the first curved surface 35 smoothly connecting the upper surface 31 and the tapered surface 33, the possibility of damage to the oil ring 1 at the time of engine assembly can be further reduced. The first curved surface 35 may have an arc shape in a cross sectional view shown in FIG. In this case, from the viewpoint of enhancing the above effects, the radius of the first curved surface 35 is preferably 0.005 mm or more in the cross sectional view shown in FIG.

The second curved surface 36 is continuous with the tapered surface 33 radially inward and is continuous with the outermost circumferential surface 34 radially outward. The second curved surface 36 is a curved surface convex on the surface side, which smoothly connects the tapered surface 33 and the outermost peripheral surface 34. The second curved surface 36 does not intersect either the straight line along the tapered surface 33 or the straight line along the outermost circumferential surface 34 in the cross-sectional view shown in FIG. 3. Thus, the possibility of damage to the oil ring 1 at the time of engine assembly can be further reduced by having the second curved surface 36 that smoothly connects the tapered surface 33 and the outermost surface 34. The second curved surface 36 may have an arc shape in a cross sectional view shown in FIG. In this case, from the viewpoint of enhancing the above effects, the radius of the second curved surface 36 is preferably 0.005 mm or more in the cross-sectional view shown in FIG.

The third curved surface 37 is continuous with the lower surface 32 of the land 30 at the radially inner side, and is continuous with the outermost circumferential surface 34 at the radial outer side. The third curved surface 37 is a curved surface convex on the surface side, which smoothly connects the lower surface 32 and the outermost surface 34. The third curved surface 37 does not intersect either the straight line along the lower surface 32 or the straight line along the outermost surface 34 in the cross-sectional view shown in FIG. 3. As described above, by having the third curved surface 37 that smoothly connects the lower surface 32 and the outermost surface 34, the possibility of damage to the oil ring 1 at the time of engine assembly can be further reduced. The third curved surface 37 may have an arc shape in a cross sectional view shown in FIG. In this case, from the viewpoint of enhancing the above effects, the radius of the third curved surface 37 is preferably 0.005 mm or more in the cross-sectional view shown in FIG.

In order to confirm the effects of the present invention, the oil rings of Examples 1 to 10 of the present invention and the oil rings 1 to 12 of Comparative Example for comparison with the present invention are prepared, and these oil rings are Evaluation of damage to the oil ring and evaluation of oil consumption were performed. The present invention is not limited to these examples.

Example 1
The oil ring body of Example 1 was produced by the following procedure. First, rolling roll forming and pultrusion were performed on a hard steel wire equivalent to JIS SWRH 77B. At this time, the nominal diameter of the molded product was 100 mm, the width along the axial direction was 2.5 mm, and the thickness along the radial direction was 2.5 mm. Next, side processing and joint processing were performed. Finally, the outer periphery lapping was performed using a perfect circle sleeve with an inner diameter of 100 mm to produce an oil ring main body.

The oil ring of Example 1 has a land width L of 0.25 mm, an outermost surface width L1 of 0.15 mm, and a projection length H of 0.036 mm for each of the pair of rail portions in the shape shown in FIGS. 1 to 3 The angle α of the tapered surface was 19.80 °.

(Example 2)
In the same manner as in Example 1, an oil ring body of Example 2 was produced. The oil ring of Example 2 has a land width L of 0.23 mm, an outermost surface width L1 of 0.15 mm, and a projection length H of 0.025 mm for each of the pair of rail portions in the shape shown in FIGS. 1 to 3 The angle α of the tapered surface was 17.35 °.

(Example 3)
In the same manner as in Example 1, an oil ring body of Example 3 was produced. The oil ring of Example 3 has a land width L of 0.17 mm, an outermost surface width L1 of 0.13 mm, and a projection length H of 0.015 mm for each of the pair of rail portions in the shape shown in FIGS. 1 to 3 The angle α of the tapered surface was 20.56 °.

(Example 4)
In the same manner as in Example 1, an oil ring body of Example 4 was produced. The oil ring according to the fourth embodiment has a land width L of 0.30 mm, an outermost surface width L1 of 0.05 mm, and a projection length H of 0.100 mm for each of the pair of rail portions in the shape shown in FIGS. The angle α of the tapered surface was 21.80 °.

(Example 5)
In the same manner as in Example 1, an oil ring body of Example 5 was produced. The oil ring of the fifth embodiment has a land width L of 0.30 mm, an outermost circumferential surface width L1 of 0.15 mm, and a protrusion length H of 0.064 mm for each of the pair of rail portions in the shape shown in FIGS. The angle α of the tapered surface was 23.11 °.

(Example 6)
In the same manner as in Example 1, an oil ring body of Example 6 was produced. The oil ring according to the sixth embodiment has a land width L of 0.25 mm, an outermost surface width L1 of 0.12 mm, and a projection length H of 0.055 mm for each of the pair of rail portions in the shape shown in FIGS. The angle α of the tapered surface was 22.93 °.

(Example 7)
In the same manner as in Example 1, an oil ring body of Example 7 was produced. The oil ring of the seventh embodiment has a land width L of 0.27 mm, an outermost surface width L1 of 0.12 mm, and a protrusion length H of 0.049 mm for each of the pair of rail portions in the shape shown in FIGS. 1 to 3 The angle α of the tapered surface was 18.09 °.

(Example 8)
In the same manner as in Example 1, an oil ring body of Example 8 was produced. The oil ring of the eighth embodiment has a land width L of 0.30 mm, an outermost surface width L1 of 0.10 mm, and a projection length H of 0.099 mm for each of the pair of rail portions in the shape shown in FIGS. 1 to 3 The angle α of the tapered surface was 26.34 °.

(Example 9)
In the same manner as in Example 1, an oil ring body of Example 9 was produced. The oil ring of the ninth embodiment has a land width L of 0.29 mm, an outermost surface width L1 of 0.03 mm, and a projection length H of 0.125 mm for each of the pair of rail portions in the shape shown in FIGS. The angle α of the tapered surface was 25.68 °.

(Example 10)
In the same manner as in Example 1, an oil ring body of Example 10 was produced. The oil ring of the tenth embodiment has a land width L of 0.30 mm, an outermost circumferential surface width L1 of 0.08 mm, and a projection length H of 0.090 mm for each of the pair of rail portions in the shape shown in FIGS. The angle α of the tapered surface was 22.25 °.

(Comparative Examples 1 to 12)
In the same manner as in Example 1, oil ring bodies of Comparative Examples 1 to 12 were produced. The dimensions of the oil rings of Comparative Examples 1 to 12 are as shown in Table 1 below. The oil ring of Comparative Example 1 does not have a tapered surface.

(Evaluation of damage to oil ring)
The piston equipped with the oil ring of each Example and each comparative example was prepared, respectively, and each piston was inserted in the cylinder from the lower end side of the liner which constitutes the inner skin of a cylinder. That is, each piston was inserted into the cylinder from the upper side of the piston (upper surface side of the oil ring). Thereafter, as the degree of damage to the oil ring, the presence or absence of the occurrence of chipping on the tapered surface was evaluated. The evaluation results are shown in Table 1 below.

(Evaluation of oil consumption)
The oil rings of each of the examples and the comparative examples were attached to the piston of a diesel engine, respectively, and the oil consumption was measured when operating at a load of 1800 rpm × 4/4 for a predetermined time. In each example and each comparative example, in order to make the tension of an oil ring the same, the coil expander of the same specification was used. Moreover, in each Example and each comparative example, the common top ring and the second ring were used. The amount of oil consumption was calculated by measuring the amount of oil contained before engine operation and the amount of oil contained after engine operation. The ratio (%) of the oil consumption of each Example and each Comparative Example when the oil consumption of Comparative Example 1 is 100% is shown in Table 1 below.

It was found from Table 1 that in Examples 1 to 10 in which the angle α of the tapered surface is more than 17 ° and less than 27 °, chipping is less likely to occur. Further, in Examples 1 to 10, it was found that the oil consumption can be reduced as compared with Comparative Examples 1 to 12 in which the angle α of the tapered surface is 17 ° or less or 27 ° or more.

Further, in Examples 1, 3 to 7, 9, 10 in which the angle α of the tapered surface is 18 ° or more and 26 ° or less, it was found that the oil consumption can be further reduced.

In Examples 1 to 10 and Comparative Examples 2 to 4, 8, 9, 11 and 12 where the projection length H is 0.015 mm or more, chipping does not occur, but the projection length H is less than 0.015 mm. It was found that in Comparative Examples 5, 6, 7 and 10, chipping occurred.

The present invention is not limited to the above embodiment, and it goes without saying that various modifications can be made without departing from the scope of the invention.

For example, although the oil ring 1 of the present invention is described as being mounted on a piston of a diesel engine in the above embodiment, the present invention is not limited to this, and the present invention can be applied to an oil ring mounted on a piston of a gasoline engine. It can also be applied.

Further, the material of the oil ring main body 10 is not limited to steel, but may be another material.

The land 30 may not have any one or more of the first curved surface 35, the second curved surface 36, and the third curved surface 37. However, if the land 30 has the first curved surface 35, the second curved surface 36, and the third curved surface 37, it is preferable in that the possibility of damage to the oil ring 1 at the time of engine assembly can be reduced.

1: oil ring 10: oil ring main body 10a: joint portion 11: web portion 12: rail portion 13: oil passing hole 14: mounting groove 20: coil expander 30: land 31: upper surface of land 32: lower surface of land 33: tapered surface Surface 34: outermost circumferential surface 35: first curved surface 36: second curved surface 37: third curved surface 41: upper end of outermost circumferential surface 42: lower end of outermost circumferential surface 43: first point 44: second point 101: Inner surface of cylinder C: Cylinder P: Piston O: Central axis of oil ring L: Land width L1: Outer peripheral surface width H: Protrusive length α: Angle of tapered surface

Claims

An oil ring body provided with lands projecting radially outward, and a coil expander mounted on a radially inner portion of the oil ring body to bias the oil ring body radially outward; It is an oil ring that has
The land is
An upper surface facing in the axial direction,
An outermost circumferential surface that is a cylindrical surface parallel to the axial direction, and is the outermost in the radial direction and faces the radial outer side,
It comprises a part of a conical surface which is expanded in diameter from the one side in the axial direction to the other side in the axial direction, and has a tapered surface located between the upper surface and the outermost peripheral surface;
An oil ring, wherein an angle formed by the tapered surface with respect to the axial direction is more than 17 ° and less than 27 °.
The upper surface is linear in a sectional view along a plane including the central axis of the oil ring,
In the cross-sectional view, an intersection point of a straight line along the upper surface and a straight line along the outermost peripheral surface is a first point, an end on the one side of the outermost peripheral surface is an upper end of the outermost peripheral surface, and the outermost peripheral surface Wherein the ratio of the distance from the upper end to the lower end to the distance from the first point to the lower end is 0.76 or less, when the other end of the second end is the lower end of the outermost surface. The oil ring according to claim 1.
The oil ring according to claim 2, wherein the distance from the first point to the lower end in the sectional view is more than 0.15 mm and not more than 0.30 mm.
When the intersection of a straight line along the upper surface and a straight line along the tapered surface is a second point in the sectional view, the outermost circumferential surface protrudes radially outward by 0.015 mm or more from the second point The oil ring according to claim 2 or 3, characterized in that.
The oil ring according to any one of claims 2 to 4, wherein a distance from the upper end to the lower end is 0.15 mm or less in the sectional view.
The oil ring according to any one of claims 1 to 5, characterized in that the surface roughness of the tapered surface is larger than the surface roughness of the outermost peripheral surface.
The upper surface is linear in a sectional view along a plane including the central axis of the oil ring,
The land further includes a first curved surface curved so as to be convex on the surface side, which is continuous with the upper surface radially inward and is continuous with the tapered surface radially outward.
The first curved surface according to any one of claims 1 to 6, wherein the first curved surface does not intersect either the straight line along the upper surface or the straight line along the tapered surface in the sectional view. Oil ring.
The oil ring according to claim 7, wherein the first curved surface is an arc shape having a radius of 0.005 mm or more in the cross sectional view.
The upper surface is linear in a sectional view along a plane including the central axis of the oil ring,
The land further includes a second curved surface curved so as to be convex on the surface side, which is continuous with the tapered surface radially inward and is continuous with the outermost peripheral surface radially outward.
The second curved surface according to any one of claims 1 to 8, wherein the second curved surface does not intersect either the straight line along the tapered surface or the straight line along the outermost peripheral surface in the sectional view. Oil ring described.
The oil ring according to claim 9, wherein the second curved surface is an arc shape having a radius of 0.005 mm or more in the cross sectional view.
The oil ring according to any one of claims 1 to 10, wherein a width along an axial direction of the oil ring main body is 2.5 mm or more.
The oil ring according to any one of claims 1 to 11, wherein the outermost circumferential surface is a surface of a hard coating layer constituting a surface layer of the land.