JP2001032934A - Three-piece oil ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain independency of action of upper and lower ear portions integrated with an expander of an three-piece oil ring while adjusting rigidity of the expander. SOLUTION: A circular expander 3 attached into a ring groove of a piston has a plurality of inner arcuate portions 3a each provided with upper ear portion 4 and a lower ear portion 5 on its upper and lower sides and arranged on the same circumference, a plurality of outer arcuate portions 3b arranged on the same circumference alternatively on an outer side of the inner arcuate portions 3a in a diameter direction, and connection portions 3c connecting the inner arcuate portions 3a to the outer arcuate portions 3b and extending in a substantial diameter direction. Rigidity of the expander 3 is reduced without decreasing the number of the ear portions 4, 5, by forming circumferentially extended of long holes 6 between the upper ear portions 4 and the lower ear portions 5 of the expander. Independent radial deformation of the upper ear portions 4 and lower ear portions 5 is easily carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an oil ring, and more particularly to a three-piece oil ring mounted on a piston of an internal combustion engine.

[0002]

2. Description of the Related Art For example, a three-piece oil ring disclosed in Japanese Utility Model Laid-Open Publication No. Sho 59-107952 has an expander mounted in a ring groove of a piston of an internal combustion engine, and upper and lower expanders in the ring groove. And a pair of rail rings respectively arranged on the sides. The inner peripheral portion of each rail ring is urged radially outward by ears provided in the inner peripheral portion of the expander having elasticity so as to protrude vertically, so that the outer peripheral portion of each rail ring is located on the cylinder bore surface. It is slidably pressed against it. Therefore, the pair of rail rings slide along the cylinder bore surface following the movement of the expander, so that the upper and lower ears of the expander are independently pressed against the corresponding rail rings so as not to affect each other. At the same time as applying pressure, it is necessary to impart appropriate rigidity to the ears. For this reason, Japanese Patent Publication No. 5-5459
As disclosed in Japanese Patent Publication No. 3 (1993), it has been considered effective to provide a slit groove in the ear of the expander and divide the ear into two parts to reduce the rigidity of the ear.

[0003]

However, the conventional three-piece oil ring has various problems. That is,
In a structure in which slit grooves are provided at the center and both ends of the ear portion to reduce the rigidity of the ear portion, if the length of one ear portion in the circumferential direction is increased, the number of upper and lower ears of the expander decreases. For this reason, the pressure of the rail ring against the cylinder bore surface becomes a non-uniform distribution in which the pressure changes in a wavy manner in the circumferential direction, and oil tends to leak into the combustion chamber from a portion where the surface pressure of the rail ring is low, so that oil consumption tends to deteriorate. As a countermeasure, it is necessary to form the slit groove as narrow as possible.However, if the slit groove is formed with a width smaller than the thickness of the expander, punching with a press becomes difficult, shortening the life of the upper die and increasing cost. Becomes

[0004] When the rigidity of the ear part is reduced to a required level by increasing the slit width, the pressure of the side rail becomes uneven, so that the slit depth is increased by another method.
The ears must be properly rigid. However, if the ear slits are deepened, fatigue breakage will occur at the base of the ears during use. Therefore, when designing a three-piece oil ring, the rigidity of the ears can be adjusted only within a very narrow appropriate range.

According to the present invention, the independence of operation between the upper ear and the lower ear integrally formed with the expander can be obtained.
It is an object to provide a piece oil ring. SUMMARY OF THE INVENTION It is an object of the present invention to provide a three-piece oil ring having an expander which has optimum rigidity according to the type of engine and can be easily manufactured. SUMMARY OF THE INVENTION It is an object of the present invention to provide a three-piece oil ring that can adjust the rigidity of an expander without reducing the number of ears, and can make the pressure of a side rail against a cylinder bore surface uniform in a circumferential direction.

[0006]

The three-piece oil ring of the present invention is mounted in a ring groove (2) of a piston (15), and an upper ear (4) and a lower ear (5) are integrated. An annular expander (3) formed on the upper and lower ears of the ring expander (3) are arranged on the upper and lower sides of the expander (3) in the ring groove (2).
(4) and a pair of rail rings (7, 8) having inner peripheral portions (7a, 8a) abutting on the lower ear portion (5). Due to the elasticity of the expander (3), the inner peripheral portions (7a, 8a) of the rail rings (7, 8) abutting on the ears (4, 5) are urged radially outward,
The outer periphery (7b, 8b) of each rail ring (7, 8) is slidably pressed against the cylinder bore surface (9). The expander (3) has upper and lower ears (4) and (5) formed on the upper and lower sides, respectively, and a plurality of inner arc parts (3a) arranged on the same circumference.
And the inner arc (3a) on the same circumference radially outside the inner arc (3a).
a) a plurality of outer arcs (3b) alternately arranged with an inner arc (3a)
And the outer arc portion (3b) and the connecting portion (3
c). An elongated hole (6) extending in the circumferential direction is formed in the expander (3) between the upper ear part (4) and the lower ear part (5).

Without reducing the number of ears (4, 5), the slot (6)
This reduces the rigidity of the expander (3),
(4) and the lower ear (5) can be easily deformed independently in the radial direction. Also, with the vertical movement of the piston (15), the upper lug (4) and the lower lug (5) are individually and independently deformed by bending stress, so there is no influence of deformation and stress transmission to each other. . In other words, when one of the upper ear part (4) and the lower ear part (5) is deformed by an external force from the rail ring (7, 8), the other is hardly affected by the long hole (6). Become. For this, the upper rail ring (7) and the lower rail ring (8)
Are independently and uniformly pressed in the circumferential direction with an appropriate urging force against the cylinder bore surface (9).

In an embodiment of the present invention, the upper ear
(4) The lower ears (5) and the slots (6) are aligned with the vertical axis. Ears above the center axis of the slot (6)
The center axis of the ear (4) or the lower ear (5) may be shifted, but it is preferable that the end of the ear (4, 5) does not protrude from the longitudinal end of the slot (6). .

[0009] A projection on which the main surfaces of the rail rings (7, 8) abut.
(10, 11) are formed in the upper and lower portions of the plurality of outer arc portions (3b), respectively, and the plurality of openings (12, 13) are arranged between a pair of circumferentially adjacent long holes (6). The pair of projections (10, 11) are arranged in alignment with the vertical axis between the plurality of openings (12, 13).

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a three-piece oil ring according to the present invention will be described below with reference to FIGS.

As shown in FIGS. 1 and 4, the three-piece oil ring (1) of the present invention comprises an expander (3) mounted in a ring groove (2) of a piston (15) and a ring groove (3). In 2), a pair of rail rings (7, 8) are provided respectively above and below the expander (3). Expander (3)
The rail rings (7, 8) are actually formed in an annular shape, but show a part of an arc for convenience of illustration. Expander (3)
A plurality of inner arc portions (3a) in which an upper ear portion (4) and a lower ear portion (5) are formed and arranged on the same circumference, and an inner arc portion (3a)
A plurality of outer arc portions (3b) alternately arranged with the inner arc portion (3a) on the same circumference on the outer side in the radial direction, and the inner arc portion (3a) and the outer arc portion (3b) are connected. A connection portion (3c) extending substantially in the radial direction, and is formed into a waveform in the radial direction by the inner arc portion (3a), the outer arc portion (3b), and the connection portion (3c). An upper protrusion (10) and a lower protrusion (11) are formed at the upper and lower sides substantially at the center of the outer arc portion (3b). As shown in FIG. 3, the upper ear (4) and the lower ear
A long hole (6) extending in the circumferential direction is formed in the spacer expander (3) between the spacer expander (3). Upper ears (4), lower ears (5)
And the long hole (6) are formed substantially coaxially with respect to the vertical center axis, and the circumferential length of the long hole (6) is the circumferential length of the upper ear (4) and the lower ear (5). In order to avoid stress concentration around the long hole (6), both ends (6a, 6b) of the long hole (6) are formed in an arc shape, and both ends (6a, 6b) are at the upper part. It protrudes in the circumferential direction from the ear part (4) and the lower ear part (5). In addition, slot (6)
Is formed substantially at the center in the vertical direction between the upper ear part (4) and the lower ear part (5). Two openings (12, 13) are formed between a pair of circumferentially adjacent long holes (6). Each opening (12,
13) has substantially the same shape as the long hole (6), but is formed to have a shorter circumferential length than the long hole (6). The ends (12a, 12b, 13a, 13b) of the openings (12, 13) are formed in an arc shape to avoid stress concentration around the openings (12, 13).

Each inner peripheral portion (7a, 8a) of a pair of rail rings (7, 8) arranged on the upper and lower portions of the expander (3) is connected to the ears (4, 5) of the expander (3). Abut The ears (4, 5) are inclined at approximately θ = 10 to 25 ° with respect to the vertical direction, and the maximum diameter of a circle formed by a plurality of ears (4, 5) arranged on the same circumference is a rail. Since the diameter of each inner circumference (7a, 8a) of the ring (7, 8) is larger than that of the inner circumference (7a, 8) of the rail ring (7, 8),
When (a) abuts the ears (4, 5) of the expander (3), the inner circumference (7a, 8a) of each rail ring (7, 8) is expanded.
Is urged radially outward by the elasticity of. For this reason, the rail rings (7, 8) are expanded radially outward, and the outer peripheral portions (7b, 8b) of each rail ring (7, 8) are slidably pressed against the cylinder bore surface (9). You. When the ends of the expander (3) abut in the ring groove (2), the expander (3) places the rail rings (7, 8) on the cylinder bore surface (9) through the ears (4, 5). It functions as a spring that urges).

In this embodiment, opposing upper ear portions are provided.
A long hole in the expander (3) between the (4) and the lower ear (5)
Since (6) is formed, the second moment of area of the expander (3) is reduced, and the rigidity of the expander (3) can be reduced. For this reason, the ears (4, 5) of the expander (3)
Can reduce the expanding force applied to the inner peripheral portion (7a, 8a) of each rail ring (7, 8) to an appropriate level. Therefore,
By changing the length or width of the long hole (6), the rigidity of the expander (3) can be adjusted to control the expanding force of the ears (4, 5). Also, upper ears (4) and lower ears (5) are formed on both sides of the long hole (6) of the ears (4, 5), so that the upper ears (4) and the lower ears (5) are formed. The interaction with the section (5) as well as the effects of deformation and stress transmission can also be reduced by the slots (6), and the upper ear (4) and the lower ear (5) allow the rail ring (5) to be reduced. 7, 8) can be pressed against the cylinder bore surface (9) independently. At that time, the outer peripheral portion (7b) of the upper rail ring (7) is disposed below the inner peripheral portion (7a), and the upper rail ring (7) is disposed in a downwardly inclined state. The rail ring (7) comes into contact with the upper surface (2a) of the ring groove (2) near the inner peripheral portion (7a). Symmetrically, the lower rail ring (8)
The outer peripheral portion (8b) of the lower rail ring (8) is disposed above the inner peripheral portion (8a), and the lower rail ring (8) is disposed in an inclined state upward. ) Near the lower surface (2b) of the ring groove (2).

Depending on the state of final processing or polishing of the cylinder bore surface (9), small irregularities of about several microns may be formed on the cylinder bore surface (9). With the vertical movement of the piston (15), the outer peripheral portions (7b, 8b) of the rail rings (7, 8) slide up and down along the cylinder bore surface (9). At this time, if small irregularities exist on the cylinder bore surface (9), bending stress is generated at the ears (4, 5) of the spacer expander (3) via the rail rings (7, 8). Since a slot (6) is provided between the upper ear (4) and the lower ear (5), the upper ear (4) and the lower ear (5) are individually separated by bending stress. In addition, since they deform independently, there is no influence of deformation and stress transmission on each other. In other words, the expander (3) by the slot (6)
The rigidity of the upper ears (4) and the lower ears (5) is reduced because the rigidity of the upper ears (4) and the lower ears (5) are separated from each other. Each easily deforms in the radial direction alone. Therefore, when one of the upper ear part (4) and the lower ear part (5) is deformed by receiving an external force from the rail ring (7, 8), the other becomes less affected by the long hole (6), The upper rail ring (7) and the lower rail ring (8) individually have improved followability with respect to the cylinder bore surface (9). Even if the straightness of the piston slap or the cylinder bore surface (9) deteriorates, the upper rail ring (7) and the lower rail ring (8) are independently pressed against the cylinder bore surface (9) with an appropriate urging force, Since a sufficient amount of oil adhering to the cylinder bore surface (9) can be scraped off by the rings (7, 8), oil consumption can be reduced.

[0015] The height of the expander (3) H, the width of the slot (6) and H _1, the ratio k ₁ = H ₁ / H of the H ₁ and H 0.04
It is 5-0.818, preferably 0.136-0.682. k ₁ values are 0.045; 0.091; 0.227; 0.3
64; 0.500; 0.636; 0.773; 0.818
Various values can be selected within the range. The H ₁ may be a plate thickness greater than the expander (3).

The circumferential length of the ears (4, 5) is L, and the long hole (6)
If the circumferential length and L _1, L ₁ and L and the ratio of k ₂ = L ₁
/ L is from 1.10 to 2.50, preferably from 1.50 to 2.2.
0. k ₂ values are 1.10; 1.20; 1.30; 1.4
0; 1.50: 1.60; 1.70; 1.80; 1.90;
2.00; 2.10; 2.20; 2.30; 2.40; 2.5
Various values can be selected within the range of zero.

The functions and effects obtained in the embodiment of the present invention are as follows. [1] Without reducing the number of ears (4, 5), the rigidity of the expander (3) is reduced by the long holes (6), and the upper ears (4) and the lower ears (5) Can be easily deformed individually in the radial direction. [2] With the vertical movement of the piston (15), the upper ear (4)
And the lower ears (5) are individually and independently deformed by the bending stress, so that they are not affected by the deformation and the transmission of stress. [3] Upper ears receiving external force from rail rings (7, 8)
When one of (4) and lower ear (5) is deformed, the other is elongated
(6) makes it less affected. [4] The upper rail ring (7) and lower rail ring (8)
Independently, it is uniformly pressed in the circumferential direction with an appropriate urging force against the cylinder bore surface (9). [5] The upper rail ring (7) and the lower rail ring (8) individually have improved followability with respect to the cylinder bore surface (9). [6] Cylinder bore surface (9) by rail ring (7, 8)
Since a sufficient amount of oil adhering to the surface can be scraped off, oil consumption can be reduced. [7] Since the expander (3) is reduced in weight by the elongated hole (6), the followability of the expander (3) to the movement of the cylinder (10) is improved. [8] The lubricating oil scraped by the rail rings (7, 8) through the elongated holes (6) formed with a relatively large cross-sectional area
From (2), it is possible to return to the crank chamber through a passage (not shown). [9] Since the rigidity of the expander (3) decreases, a relatively large gap is formed between the upper rail ring (7) and the upper surface (2a) of the ring groove (2) during the ascent stroke of the piston (15). Is formed. Also, a relatively large gap is formed between the lower rail ring (8) and the bottom surface (2b) of the ring groove during the downward stroke of the piston (15). Oil can be scraped into the ring groove (2) through these gaps. [10] A sufficient amount of oil adhering to the cylinder bore surface (9) can be scraped off to reduce oil consumption. [11] By changing the size and shape of the long hole (6), the rigidity of the expander (3) can be adjusted to control the expanding force of the ears (4, 5). [12] Compared to the slit cut in the axial direction, the change in the plate width is small, so that the concentration of stress during use is small, and there is no risk of breakage of the expander (3) or the ears (4, 5). [13] An expander (3) having optimal rigid ears (4, 5) for each engine can be manufactured. [14] Spacer expander with low stress concentration (3)
Is obtained.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the displacement of the ears (4, 5) of the three-piece oil ring according to the present invention during operation of the engine will be described below.

An oil ring having an outer diameter of 87.5 mm and a thickness of 3 mm is used to improve the level at which the rigidity of the ears (4, 5) of the expander (3) is reduced and to follow the cylinder bore surface (9). The degree of completion was confirmed by the following test. Expander (3)
All of the ears (4, 5) had a pitch of 7.6 mm, the height of the slot (6) was all 0.6 mm, and the width of the expander (3) was all about 2.0 mm. As shown in FIG. 5, the test method is as follows. A load P (g) is applied to the lower rail ring (8), the weight P when the rail ring (8) is pushed in, and the ears (4, 5) of the expander (3). ) Was measured. The load is P, the width of the slot (6) is S (mm), and the displacement of the expander (3) ears (4, 5) on the load P side is S ₁ (μ
m), the displacement of the other expander (3) ears (4, 5) is S
Table 1 shows the measurement results as ₂ (μm).

[0020]

[Table 1]

If the rigidity of the expander (3) and the ears (4, 5) of the expander (3) is high, the change amount of S ₁ is small for a certain P value, and S ₂ / S ₁ becomes 1. Get closer. Conversely, ears
If the flexibility of (4, 5) is high, for the same P value, the amount of change in S ₁ is large, but smaller than the S ₂ / S ₁ ratio of 1. Table 1, who from conventional inventions indicates that the displacement amount S ₂ with respect to the displacement S ₁ small. That is, even if one of the rail rings (7, 8) is displaced due to the occurrence of a stick-slip phenomenon between the cylinder bore surface (9) and the outer peripheral surface of the rail rings (7, 8), the invention product can be moved to the other. Is hardly affected by one side,
There is an advantage of excellent followability to (3). Due to the good followability to the expander (3), the adhesion to the cylinder bore surface (9) is improved, and the oil consumption can be reduced by sufficiently controlling the oil film thickness.

[0022]

According to the present invention, as described above, a lightweight three-piece oil ring which achieves good operation performance and consumes little oil can be obtained without reducing the number of ears.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a three-piece oil ring according to the present invention.

FIG. 2 is a partial plan view of the three-piece oil ring shown in FIG.

FIG. 3 is a partial development view of the three-piece oil ring shown in FIG. 1;

FIG. 4 is a sectional view of a three-piece oil ring according to the present invention installed in a ring groove of a piston.

FIG. 5 is a sectional view showing a state in which the displacement of the ear of the expander is measured.

[Explanation of symbols]

(1) ・ ・ 3-piece oil ring, (2) ・ ・ Ring groove,
(3) ··· Expander, (3a) ··· Inner arc, (3b) ···
Outer arc, (3c) ・ ・ Connection, (4, 5) ・ ・ Ear, (6)
..Elongated holes, (7, 8) ·· Rail rings, (7a, 8a) ··
Inner circumference, (9) Cylinder bore surface, (10, 11) Projection, (15) Piston,

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Miyuki Shinada 1-37 Hokutocho, Kashiwazaki-shi, Niigata Prefecture Inside the Riken Kashiwazaki Plant (72) Inventor Katsumi Murayama 1-37 Hokutocho, Kashiwazaki-shi, Niigata Riquet Inc. F K term in Kashiwazaki Plant (reference) 3J044 AA12 AA18 AA20 BC06 CB29 DA09

Claims (8)

[Claims] 1. An annular expander mounted in a ring groove of a piston and having an upper ear portion and a lower ear portion integrally formed, and respectively disposed above and below the expander in the ring groove. And a pair of rail rings having an inner peripheral portion in contact with the upper ear portion and the lower ear portion, and urges each inner peripheral portion of the rail ring in contact with the ear portion radially outward by elasticity of the expander. Then, in the three-piece oil ring that slidably presses each outer peripheral portion of the rail ring against the cylinder bore surface, the expander has an upper ear portion and a lower ear portion, and is arranged on the same circumference. A plurality of inner arc portions, a plurality of outer arc portions arranged alternately with the inner arc portions on the same circumference radially outward from the inner arc portions, and connecting the inner arc portions and the outer arc portions to form a substantially radial An upper ear and a lower ear 3-piece oil ring a long hole extending in a circumferential direction between, characterized in that formed on the expander. 2. The three-piece oil ring according to claim 1, wherein the upper ear portion, the lower ear portion, and the long hole are arranged in alignment with a vertical axis. 3. The height of the expander is H, and the width of the slot is H.
When _1, the ratio k ₁ = H ₁ / H of the H ₁ and H 0.045～
3. The three-piece oil ring according to claim 1 or 2, which has a diameter of 0.818. 4. The three-piece oil ring according to claim 3, wherein k ₁ = 0.136 to 0.682. The circumferential length of 5. ears L, when the circumferential length of the long holes and L _1, the ratio k ₂ = L ₁ / L of L ₁ and L,
The three-piece oil ring according to any one of claims 1 to 4, wherein the number is from 1.10 to 2.50. 6. The method according to claim 5, wherein k ₂ = 1.50 to 2.20.
The three-piece oil ring according to 1. 7. The method according to claim 1, wherein projections are formed on upper and lower portions of the plurality of outer arc portions, respectively.
Peace oil ring. 8. A plurality of openings are arranged in alignment between a pair of circumferentially adjacent long holes, and a pair of projections are arranged in alignment with a vertical axis between the plurality of openings. The three-piece oil ring according to any one of claims 1 to 7, wherein a main surface of the rail ring contacts the pair of protrusions.