JP3902352B2 - Thin 3-piece combination oil ring - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a three-piece combination oil ring.
[0002]
[Prior art]
The piston ring is required to have a thinner width and lower tension for the purpose of high-speed engine rotation, high output, and fuel saving.
A thin oil ring is known from Japanese Patent Laid-Open No. 4-78376. The known three-piece type combined oil ring 20 has a structure in which a spacer expander 19 is sandwiched between two side rails 21 and 22 as shown in FIG. 1, and the spacer expander 19 is made of a steel plate having a substantially H-shaped cross section. This is a ring-shaped torus having slits that are formed and alternately cut from the inner peripheral side and the outer peripheral side. This thin oil ring 20 in the axial direction has ensured good sealing performance in a wide rotation range from low speed to high speed.
[0003]
[Problems to be solved by the invention]
However, in response to the recent demand for lowering the oil ring tension, the contact surface pressure between the side rail and the cylinder inner wall surface decreases, and as shown in FIG. There is a problem that the sealing performance is impaired without being able to follow the unevenness of 17.
[0004]
The present invention has been made to solve this problem, and the problem is a thin and low tension three-piece type combined oil ring that can sufficiently follow the irregularities formed on the inner wall surface of the cylinder. An object of the present invention is to provide a device that maintains a good sealing property.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the means employed by the present invention is to determine the axial distance between the tips of the outer peripheral ends of the upper and lower side rails, that is, the axial interval between the points at which the upper and lower side rails contact the cylinder inner wall surface. This is because the followability of the upper and lower side rails to the cylinder inner wall surface is improved by making it smaller than the axial distance between the centers.
[0006]
A bevel surface inclined to the spacer expander side having a radial width of 10 to 25% of the side rail is formed on the outer peripheral side of the ring groove side end surface of the side rail, and the outer peripheral end of the side rail is the side rail spacer on the spacer expander side. It is preferable to form on the expander side end surface such that the ring groove side is continuous with the bevel surface.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described based on embodiments shown in the drawings.
FIG. 2 is a partial perspective view of a three-piece combination oil ring according to an embodiment of the present invention. FIG. 3 is a longitudinal sectional view of a piston in which the same oil ring is mounted in a ring groove.
[0008]
The oil ring 1 of the present invention includes a single spacer expander 2 and two side rails 3 and 4 sandwiching the spacer expander 2 from above and below. The side rails 3 and 4 are plate-like annular bodies and have joints separated in the same manner as ordinary piston rings.
The illustrated oil ring spacer expander 2 is a ring-shaped member having slits 18 formed from a steel material having a substantially H-shaped cross section and alternately cut from the inner peripheral side and the outer peripheral side. The axial width is 1.2 to 1.5 mm, but the spacer expander may have any shape. However, the combined axial direction width dimension is preferably 1.5 mm or less.
[0009]
The axial distance between the tips 7 and 8 of the outer peripheral ends 5 and 6 of the upper and lower side rails 3 and 4 is smaller than the axial center between the centers of the upper and lower side rails 3 and 4.
As shown in FIG. 3, when the oil ring 1 is installed in the ring groove 16 of the piston 15, the distal ends 7, 8 of the outer peripheral ends 5, 6 of the upper and lower side rails 3, 4 are pushed by the spacer expander 2 and It contacts the wall surface 17. In order to make the axial interval between the tips 7 and 8 smaller than the axial interval between the centers of the upper and lower side rails 3 and 4, on the outer peripheral side of the ring groove side end surfaces 9 and 10 of the side rails 3 and 4, toward the spacer expander side. Inclined bevel surfaces 13 and 14 are formed. The spacer expander side of the outer peripheral end portions 5 and 6 of the side rails 3 and 4 smoothly continues to the side rail spacer expander side end surfaces 11 and 12, and the opposite ring groove side continues to the side rail ring groove end surfaces 9 and 10, respectively. .
[0010]
The radial width L1 of the bevel surfaces 13 and 14 is limited to 10 to 25% of the radial width L of the upper and lower side rails 3 and 4. If L1 is 10% or less of L, the axial distance between the cylinder inner wall surface contact points of the upper and lower side rails increases due to wear of the upper and lower side rail tips 7 and 8, and the effect of the present invention is reduced. Further, if L1 is 25% or more of L, the rigidity of the upper and lower side rails 3 and 4 is reduced and deformed during operation, and proper oil control cannot be performed.
[0011]
Next, the following capability with respect to the cylinder inner wall surface of the conventional example and the embodiment will be described based on FIGS.
The upper and lower side rails 21, 22, 3, 4 of the oil ring 20, 1 mounted in the ring groove 16 of the piston 15 are in sliding contact with the cylinder inner wall surface 17 with a constant tension by the spacer expanders 19, 2. If the cylinder inner wall surface 17 is uneven, or if the piston 15 is swung, the upper and lower tip ends 23, 24 are required to contact the upper and lower side rail tips 23, 24, 7, 8 together with the cylinder inner wall surface 17. , 7 and 8 need to make a difference in the radial protrusion length from the ring groove 16. This radial protrusion length difference is more likely to occur as the axial distance between the upper and lower tips 23, 24, 7, and 8 increases.
[0012]
Since the conventional oil ring 20 has a relatively long axial distance between the tips 23 and 24 of the upper and lower side rails 21 and 22, the radial protrusion length difference is also large, and a low-tension spacer expander cannot cope with it. . For this reason, as shown in FIG. 1, even if the tip 23 of one of the upper and lower side rails 21 is separated from the cylinder inner wall surface 17 or not separated, the tension on the cylinder inner wall surface 17 is remarkably lowered and the sealing performance is deteriorated. It will be enough.
[0013]
On the other hand, the oil ring 1 of the embodiment has a relatively short axial distance between the tips 7 and 8 of the upper and lower side rails 3 and 4, so the radial protrusion length difference is small and can be used with a low tension spacer expander. As shown in FIG. 4, the tips 7 and 8 of the upper and lower side rails 3 and 4 always come into contact with the inclined cylinder inner wall surface 17 with a predetermined tension to ensure a sealing property.
[0014]
【The invention's effect】
In the three-piece type combined oil ring of the present invention, the axial distance between the tips of the outer peripheral ends of the upper and lower side rails is smaller than the axial distance between the centers of the upper and lower side rails. Even if the surface of the cylinder is uneven, or the piston swings, the force exerted on the inner wall of the cylinder will not be affected even if the tip of one of the upper and lower side rails is separated from or in contact with the inner wall of the cylinder. There is no significant drop.
[0015]
Therefore, the combined oil ring of the present invention has an excellent effect that the followability of the side rail with respect to the inner wall surface of the cylinder is improved as compared with the conventional thin three-piece oil ring, and good sealing performance can be secured.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing the followability of a conventional cylinder inner wall surface unevenness,
FIG. 2 is a partial perspective view of a three-piece combined oil ring according to an embodiment of the present invention;
3 is a cross-sectional view of an essential part of an engine equipped with the embodiment of FIG.
FIG. 4 is a cross-sectional view showing the followability of the cylinder inner wall surface unevenness of the embodiment;
[Explanation of symbols]
1: Oil ring 2: Spacer expander 3, 4: Side rail 5, 6: Outer peripheral end 7, 8: Tip 9, 10: Ring groove side end surface 11, 12: Spacer expander side end surface 13, 14: Bevel surface 15: Piston 16: Ring groove 17: Cylinder inner wall surface 18: Slit 19: Spacer expander 20: Oil ring 21, 22: Side rail 23, 24: Tip

Claims (1)

An oil ring (1) comprising a spacer expander (2) and two side rails (3, 4) arranged so as to sandwich the spacer expander from above and below, and an outer peripheral end (5 6) The axial distance between the tips (7, 8) of the side rails is made smaller than the axial distance between the centers of the side rails, and the outer peripheral side of the ring groove side end faces (9, 10) of the upper and lower side rails of the flat annular body Forming a bevel surface (13, 14) inclined to the spacer expander side, the spacer expander side of the side rail outer peripheral end portion to the upper and lower side rail spacer expander side end surfaces (11, 12), and the ring groove side smoothly made continuous to each of the bevel surface of 10 to 25 percent by thin width 3-piece union, characterized in that the radial width of the side rails of the radial width of the bevel surface Oil ring.

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