JP2004197820A - Combined oil ring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an assembled oil ring capable of reducing friction and having satisfactory oil scraping capacity. <P>SOLUTION: The combined oil ring 4 comprises an oil ring 5 having upper and lower rails 7 and 8, and an expander 6 pushing the oil ring 5 outward in a radial direction. Upper and lower faces of the oil ring 5 are formed on barrel curved faces 14 and 19 from an inner peripheral end to a root portion of an outer peripheral projections 10 and 15 of the upper and lower rails 7 and 8. An axial gap of the barrel curved faces 14 and 19 is set 0.01 to 0.1 mm. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a combination oil ring mounted on a reciprocating piston such as an internal combustion engine or a compressor to perform oil control.
[0002]
[Prior art]
2. Description of the Related Art A two-piece steel combination oil ring including an oil ring and an expander is used in an internal combustion engine (for example, see Patent Document 1). This combination oil ring is often used in diesel engines, but recently, it is also often used in gasoline engines because of its low tension reduction rate due to wear and excellent durability. In addition, due to recent demands for lower fuel consumption, low friction is also required for oil rings. Measures to reduce friction related to the oil ring include lowering the tension and treating the outer peripheral surface and upper and lower surfaces with low friction.
[0003]
As shown in FIG. 3, the oil ring 5A in the two-piece combined oil ring 4A has an oil window 22 through which upper and lower two rails 7A and 8A are connected by a web 9 and through which oil scraped off by the rails passes. Are formed on the web 9 in large numbers. The outer peripheral side projection 10 of the upper rail 7A has a substantially trapezoidal cross section including an outer peripheral surface 11 and a pair of upper and lower inclined surfaces 12, 13 connected to the outer peripheral surface 11. The upper surface of the oil ring 5A is formed on a flat surface 14a from the inner peripheral end to the base of the outer peripheral side projection 10, and the flat surface 14a and the inner peripheral surface 24 and the inclination of the flat surface 14a and the outer peripheral side projection 10 are formed. The upper surfaces 12 each form a corner. The lower rail 8A is also formed in the same manner as the upper rail 7A. 1 is a piston, 2 is a cylinder, 3 is a ring groove, and 6 is a coil expander.
[0004]
[Patent Document 1]
Japanese Patent Publication No. Hei 3-29979 [0005]
[Problems to be solved by the invention]
When the combined oil ring is mounted in the ring groove of the piston and slides in the cylinder in the axial direction, the oil ring also slides in the ring groove in the radial and circumferential directions due to the swing of the piston. When sliding in the radial direction, the corners between the flat surface of the upper and lower surfaces of the oil ring and the inner peripheral surface, and the corner between the flat surface and the inclined upper surface of the outer peripheral side protrusion are locally located on the upper and lower surfaces of the ring groove. As a result, the oil ring is hindered from moving in the radial direction, and as a result, the friction in the axial direction of the outer periphery of the oil ring may increase.
[0006]
The present invention has been made in view of the above points, and an object of the present invention is to provide a combined oil ring that can reduce friction and has good oil scraping ability.
[0007]
[Means for Solving the Problems]
The present invention employs the following means in order to solve the above problems. That is,
The present invention relates to a combined oil ring having an oil ring having upper and lower rails and an expander pressing the oil ring radially outward,
The upper and lower surfaces of the oil ring are formed in a barrel curved surface from the inner peripheral end to the base of the outer peripheral side protrusion of the upper and lower rails.
[0008]
According to the above configuration, when the cylinder bore slides, the corners between the barrel curved surface and the inner peripheral surface of the upper and lower surfaces of the oil ring, and the corners between the barrel curved surface and the base of the rail outer peripheral side protrusion are formed on the upper and lower surfaces of the ring groove. It is possible to prevent strong contact locally, and it is possible to suppress a local increase in friction due to each corner between the barrel curved surface of the upper and lower surfaces of the oil ring and the inner peripheral surface and the protrusion on the outer peripheral side of the rail. Is smooth, and the friction in the axial direction on the outer periphery of the oil ring can be reduced.
[0009]
In the above description, the axial head of the barrel curved surface is preferably 0.01 to 0.1 mm. If it is less than 0.01 mm, a strong hit at the corner is likely to occur, and if it exceeds 0.1 mm, the sealing property is reduced.
[0010]
The present invention can also be configured as follows. That is,
The present invention relates to a combined oil ring having an oil ring having upper and lower rails and an expander pressing the oil ring radially outward,
The upper and lower surfaces of the oil ring are formed in a flat surface from the inner peripheral end to the root of the outer peripheral side projection of the upper and lower rails, and the corner between the flat surface and the inner peripheral surface and the flat surface and the upper and lower rails are formed. A chamfer is formed at a corner with the outer peripheral side projection.
[0011]
According to the above configuration, when the cylinder bore slides, the corners between the flat surface and the inner peripheral surface of the upper and lower surfaces of the oil ring, and the corners between the flat surface and the protrusion on the outer periphery of the rail are locally located on the upper and lower surfaces of the ring groove. Strong contact can be prevented, and the local increase in friction due to the corners between the flat surface of the upper and lower surfaces of the oil ring and the inner peripheral surface and the protrusion on the outer peripheral side of the rail can be suppressed, so that the oil ring moves in the radial direction. This makes it possible to reduce friction in the axial direction on the outer periphery of the oil ring.
[0012]
In the above, it is preferable that the radial length of the chamfer on the inner peripheral side is 0.05 to 0.5 mm and the axial length is 0.01 to 0.1 mm. If the length in the radial direction is less than 0.05 mm, a strong hit at the corner tends to occur, and if it exceeds 0.5 mm, the sealing property is reduced. If the length in the axial direction is less than 0.01 mm, a strong hit at the corner is likely to occur, and if it exceeds 0.1 mm, the sealing property is reduced.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0014]
In FIG. 1, 1 is a piston, 2 is a cylinder, and a combined oil ring 4 is mounted in a ring groove 3 formed on the outer periphery of the piston 1. The combination oil ring 4 is a two-piece type steel combination oil ring, and includes an oil ring 5 and a coil expander 6.
[0015]
The oil ring 5 is a steel ring having an abutment and having a substantially I-shaped cross section, and a pair of upper and lower rails 7 and 8 extending in the circumferential direction and a straight web 9 extending in the circumferential direction and connecting the upper and lower rails 7 and 8. It consists of
[0016]
The outer peripheral side protruding portion 10 of the upper rail 7 has a substantially trapezoidal cross section including an outer peripheral surface 11 and a pair of upper and lower inclined surfaces 12 and 13 connected to the outer peripheral surface 11, and becomes narrower toward the outer peripheral surface. ing. The upper surface of the oil ring 5 is formed as a barrel curved surface 14 from the inner peripheral end to the root of the outer peripheral side projection 10. The barrel curved surface 14 is formed on the inner peripheral surface 24 and the inclined upper surface 12 of the rail outer peripheral side projection 10. Connected smoothly. The axial drop a of the barrel curved surface 14 is in the range of 0.01 to 0.1 mm.
[0017]
The lower rail 8 is also formed in the same manner as the upper rail 7, 15 is an outer peripheral projection, 16 is an outer peripheral surface, 17 and 18 are a pair of vertically inclined surfaces connected to the outer peripheral surface 16, and the lower surface of the oil ring 5 is A barrel curved surface 19 is formed from the inner peripheral end to the root of the outer peripheral side projection 15, and the barrel curved surface 19 is smoothly connected to the inner peripheral surface 24 and the inclined lower surface 18 of the rail outer peripheral side projection 15. . The axial drop of the barrel curved surface 19 is in the range of 0.01 to 0.1 mm.
[0018]
A coil expander 6 is mounted in an inner circumferential groove 20 formed on the inner circumferential side of the oil ring 5, and presses the oil ring 5 outward in the radial direction, that is, against the inner circumferential surface 2a of the cylinder.
[0019]
Therefore, the oil ring 5 pressed against the cylinder inner peripheral surface 2a by the coil expander 6 slides on the cylinder inner peripheral surface 2a, and the oil scraped from the cylinder inner peripheral surface 2a removes the oil from the outer periphery of the upper and lower rails 7, 8. From the outer peripheral groove 21 between the side protrusions 10 and 15, the piston 9 moves to the inner peripheral side of the oil ring 5 through a plurality of oil windows 22 formed in the web 9 at intervals in the circumferential direction. The oil is returned to the oil pan through the formed oil return hole 23.
[0020]
At this time, even if the piston 1 is tilted, the corners between the barrel curved surfaces 14, 19 on the upper and lower surfaces of the oil ring and the inner peripheral surface 24, and the roots of the barrel curved surfaces 14, 19 and the rail outer peripheral side projections 10, 15 are formed. Can be prevented from strongly hitting the upper and lower surfaces 3a, 3b of the ring groove 3 locally, and the barrel curved surfaces 14, 19 of the upper and lower surfaces of the oil ring, the inner peripheral surface 24, and the rail outer peripheral projections 10, Since the local increase in friction due to each corner with the oil ring 15 can be suppressed, the radial movement of the oil ring 5 becomes smooth, and the axial friction on the outer periphery of the oil ring 5 can be reduced.
[0021]
FIG. 2 shows another embodiment 2 of the present invention. The second embodiment is the same as the first embodiment except that the upper and lower surfaces of the oil ring are different from the first embodiment.
[0022]
In the second embodiment, the upper surface of the oil ring 5 is formed as a flat surface 14a from the inner peripheral end to the base of the outer peripheral projection 10 of the upper rail 7. Chamfers 14b and 14c are formed at corners between the flat surface 14a and the inner peripheral surface 24 and at corners between the flat surface 14a and the inclined upper surface 12 of the outer peripheral projection 10 of the upper rail 7. Is smoothly connected to the inner peripheral surface 24 and the inclined upper surface 12 of the outer peripheral projection 10 of the upper rail 7 by chamfers 14b and 14c. The radial length b of the chamfer 14b on the inner peripheral side is in the range of 0.05 to 0.5 mm, and the axial length c is in the range of 0.01 to 0.1 mm.
[0023]
The lower rail 8 is also formed in the same manner as the upper rail 7, 15 is an outer peripheral side projection, 16 is an outer peripheral surface, and 17 and 18 are a pair of inclined upper and lower surfaces connected to the outer peripheral surface 16, and a lower surface of the oil ring 5. Is formed on the flat surface 19a from the inner peripheral end to the root of the outer peripheral side projection 15 of the lower rail 8. Chamfers 19b and 19c are formed at corners between the flat surface 19a and the inner peripheral surface 24 and at corners between the flat surface 19a and the inclined lower surface 18 of the outer peripheral projection 15 of the lower rail 8. Is smoothly connected to the inner peripheral surface 24 and the inclined lower surface 18 of the outer peripheral projection 15 of the lower rail 8 by chamfers 19b and 19c. The radial length of the chamfer 19b on the inner peripheral side is in the range of 0.05 to 0.5 mm, and the axial length is in the range of 0.01 to 0.1 mm.
[0024]
Also in the case of the second embodiment, even when the piston 1 is tilted, the corners between the flat surfaces 14a, 19a of the oil ring upper and lower surfaces and the inner peripheral surface 24, and the flat surfaces 14a, 19a and the rail outer peripheral side protrusion 10 are formed. , 15 can be prevented from locally strongly contacting the upper and lower surfaces 3a, 3b of the ring groove 3, and the flat surfaces 14a, 19a of the upper and lower surfaces of the oil ring, the inner peripheral surface 24, and the outer periphery of the rail. Since the local increase in friction due to each corner with the side protrusions 10 and 15 can be suppressed, the radial movement of the oil ring 5 becomes smooth, and the axial friction on the outer periphery of the oil ring 5 can be reduced.
[0025]
【The invention's effect】
As described above, according to the combination oil ring of the present invention, the friction can be reduced and the oil scraping ability is good.
[Brief description of the drawings]
FIG. 1 shows an embodiment of the present invention, in which (a) is a longitudinal sectional view showing a combined oil ring mounted on a piston in a cylinder, and (b) is an enlarged sectional view showing a part of an upper rail. .
FIG. 2 shows another embodiment of the present invention, in which (a) is a longitudinal sectional view showing a combined oil ring mounted on a piston in a cylinder, and (b) is an enlarged sectional view showing a part of an upper rail. is there.
3A and 3B show a conventional example, in which FIG. 3A is a longitudinal sectional view showing a combined oil ring mounted on a piston in a cylinder, and FIG. 3B is an enlarged sectional view showing a part of an upper rail.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Piston 2 Cylinder 2a Cylinder inner peripheral surface 3 Ring groove 3a Ring groove upper surface 3b Ring groove lower surface 4 Combined oil ring 5 Oil ring 6 Coil expander 7, 8 Rail 9 Web 10, 15 Outer side projection 11, 16 Outer surface 12 , 17 Inclined upper surface 13, 18 Inclined lower surface 14, 19 Barrel curved surface 14a, 19a Flat surface 14b, 14c, 19b, 19c Chamfer 20 Inner circumferential groove 21 Outer circumferential groove 22 Oil window 23 Oil return hole 24 Inner circumferential surface

Claims (4)

In a combined oil ring having an oil ring having upper and lower rails and an expander for pressing the oil ring outward in the radial direction,
A combination oil ring, wherein upper and lower surfaces of the oil ring are formed in a barrel curved surface from an inner peripheral end to a root portion of an outer peripheral side protrusion of the upper and lower rails. In a combined oil ring having an oil ring having upper and lower rails and an expander for pressing the oil ring outward in the radial direction,
The upper and lower surfaces of the oil ring are formed in a flat surface from the inner peripheral end to the root of the outer peripheral side projection of the upper and lower rails, and the corner between the flat surface and the inner peripheral surface and the flat surface and the upper and lower rails are formed. A combination oil ring, wherein a chamfer is formed at a corner with an outer peripheral side projection. The combination oil ring according to claim 1, wherein an axial head of the barrel curved surface is 0.01 to 0.1 mm. 3. The combination oil ring according to claim 2, wherein the inner chamfer has a radial length of 0.05 to 0.5 mm and an axial length of 0.01 to 0.1 mm.

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