JPH10252890A - Oil ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a manufacturing cost without impairing conventional performance by forming an inner peripheral side cross-sectional shape in an outward swelling almost circular arc shape, and arranging oil dropping parts on a contact surface of lower and central projecting strips with a cylinder wall. SOLUTION: In an oil ring 1, a central projecting strip 4 is arranged in an intermediate part between outer peripheral side upper and lower projecting strips 2 and 3, and a piston contact surface 5 whose cross sectional shape is an outward swelling almost circular arc shape is arranged on the inner peripheral side. Oil drops 6 and 6 are arranged on a contact surface of lower and central projecting strips with a cylinder wall, and a through hole 7 reaching an inner periphery from an outer periphery is arranged in a groove part between the respective projecting strips. Oil scraped up by the projecting strips is returned to a cylinder lower part, and is also efficiently returned to the cylinder lower part even by passing through the through hole. A wire rod for the oil ring is cut in a necessary length, and a coil ring is worked so that the projecting strips become the outer peripheral side and a circular arc shape becomes the inner peripheral side, and hard chrome plating is performed on an outer peripheral surface. A coil expander is obviated, and a manufacturing cost can be sharply reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a steel oil ring used for a piston of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, a steel oil ring of this kind has been disclosed in, for example, JP-A-61-45172 and JP-A-4-7.
An oil ring having a two-piece structure as disclosed in Japanese Patent Publication No. 8375 or the like is generally used.

As shown in FIGS. 3 (a) and 3 (b), the oil ring 8 having a two-piece structure has a cross-sectional structure composed of upper and lower side rails and a thin web portion connecting the two side rails. A ring-shaped steel ring body 9 and a coil expander 10 for pressing the ring body 9 against the cylinder wall are provided. An outer peripheral groove for receiving the scraped oil is formed on the outer peripheral surface of the ring main body 9, and an inner peripheral groove for inserting the coil expander 10 is formed on the inner peripheral surface. Further, a large number of elongated oil holes are formed in the thin web to allow the scraped oil to escape from the outer circumferential groove to the inner circumferential groove.

[0004]

The above-mentioned ring body 9 is
Manufactured by cold rolling using a steel wire rod with a round cross section. However, it is difficult to process the side rails, outer circumferential grooves and inner circumferential grooves, and the web is very thin. Therefore, the number of processing steps is very large. Further, it is necessary to separately manufacture and combine the coil expander 10. The coil expander 10 is formed by processing a high carbon steel material into a coil shape so as to obtain a contact pressure on the cylinder wall surface of the ring main body 9. Therefore, the two-piece oil ring is excellent in performance such as oil scraping property and ability to maintain contact pressure, but has a problem that the total cost is high. It is a fatal problem.

An object of the present invention is to provide an oil ring whose production cost is very low without impairing the performance of a conventional two-piece oil ring.

[0006]

In order to achieve the above object, in a steel oil ring used for a piston of an internal combustion engine, a sectional shape on an inner peripheral side is formed into a substantially circular arc shape bulging outward. And, the cross-sectional shape of the outer peripheral side is formed in a substantially U-shape, and the upper and lower ridges are provided, and at least one or more oil dropping parts are provided on the contact surface of the lower ridge with the cylinder wall. As the first invention,

[0007] In the first aspect of the invention, a central ridge is provided between the upper and lower ridges, and at least one or more oil dropping portion is provided on a contact surface of the central ridge with a cylinder wall. As the second invention,

In the second invention, a third invention is characterized in that the oil dropping portions of the central ridge and the lower ridge are provided at upper and lower asymmetric positions.

In the first or second invention, a fourth invention is characterized in that a plurality of through holes extending from the outer peripheral side to the inner peripheral side are provided in the groove between the ridges.

In the first, second, third and fourth inventions, the thickness (T) of the oil ring is 1.5 to 5 m.
m, the width dimension (W) including the ridge is 2 to 4 mm, the radius of curvature R of the substantially circular arc shape on the inner peripheral side is R = (1/2 to 3/4) T, and the thickness of the ridge ( t) is 0.5 to 1.0 mm,
A fifth invention is that the height (h) of the ridge is 0.2 to 0.8 mm.

By the way, the numerical limitation in the above configuration is as follows.
It is determined based on the results obtained by a number of experiments, and the outline is as follows. When the thickness T of the oil ring is set to 1.5 to 5 mm, if the thickness is less than 1.5 mm, the rigidity is low and the oil scraping property cannot be maintained at the same level as when an expander coil is used.
If it is larger than m, the ring workability is reduced.
Also, the width dimension W including the ridge was set to 2 to 4 mm because
If the thickness is less than mm, the thickness excluding the ridge becomes thin, and rigidity cannot be obtained. If the thickness is more than 4 mm, the ring workability decreases. The reason why the radius of curvature R of the substantially arc shape on the inner peripheral side of the oil ring is R = (1/2 to 3/4) T is as follows.
If it is smaller than (1/2) T, the arc becomes too close to a straight line, the followability to the cylinder wall decreases, and (3/4) T
If it is larger, the stability when incorporated into the piston is reduced. Further, the thickness (t) of the ridge is 0.5 to
The reason why the thickness is set to 1.0 mm is that if the thickness is less than 0.5 mm, rolling or cutting becomes difficult. If the thickness is more than 1.0 mm, the oil scraping property is inferior. 0.2 to 0.8 mm is smaller than 0.2 mm, oil receiving space cannot be secured, and 0.8 m
When it is larger than m, the stiffness of the ridge decreases, and both have a bad influence on the oil scraping property.

Since the oil ring of the present invention has a thickness T of 1.5 to 5 mm and a width W including a ridge of 2 to 4 mm, the oil ring has high rigidity and can be used without a coil expander.
The contact pressure between the oil ring and the cylinder wall can be kept high, and the thickness of the ridge is 0.5 to 1.0 mm and the height of the ridge is 0.2 to 0.8 mm. The same oil scraping property as the sex ring can be maintained.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2, reference numeral 1 denotes an oil ring. The oil ring 1 has upper and lower ridges 2 and 3 on the outer peripheral side, and a central ridge 4 between the two ridges 2 and 3. And a substantially arc-shaped piston contact surface 5 having a radius of curvature R whose section swells outward on the inner peripheral side. In addition, at least one or more oil dropping portions 6, 6 are provided at upper and lower asymmetric positions on contact surfaces of the lower ridge 3 and the central ridge 4 with the cylinder wall. Is provided with a plurality of through holes 7 extending from the outer periphery to the inner periphery.
Here, a plurality means that there are at least two or more.

Since the oil ring of the present invention has a substantially arc-shaped cross section on the inner peripheral side, the piston contact surface makes point contact with the piston to exhibit the function of freely changing the angle, and the outer peripheral side The ridges have excellent function to follow the cylinder wall. In addition, the oil that has been scraped off by the ridges can be efficiently returned to the cylinder lower portion by the oil dropping portions on the lower and center ridges on the outer circumference side. By the plurality of through holes reaching the side, oil collected by the ridge can be returned to the lower portion of the cylinder through the through holes more efficiently.

[0016]

EXAMPLE A 0.8 mm C carbon steel wire having a diameter of 5.5 mm was heat-treated and drawn to a wire having a diameter of 3.2 mm, and thereafter, annealing and rolling were repeated to form a wire parallel to the upper, lower, middle and lower surfaces. The ridges of the book are formed continuously in the longitudinal direction, and at the same time, the other side surface is formed into a substantially circular arc shape having a radius of curvature R whose cross-sectional shape bulges outward. At this time, the thickness dimension T = 1.8 m
m, wire width W = 1.8 mm, radius of curvature R is 0.9
mm. Then, after at least one or more oil dropping portions are provided at appropriate positions of the central ridge and the lower ridge at the upper and lower asymmetric positions, finishing treatment is performed to impart straightness, strength, and the like. Next, through holes were formed at equal intervals by laser processing between the ridges to obtain a wire for an oil ring. By the way, the above-mentioned projection can be obtained by cutting.

The thickness (t) of the ridge is 0.6 mm and the height (h) is 0.3 mm, and the oil drop portions of the lower and center ridges are 2 mm in width and 0.3 mm in depth. The pitch is 5 mm.

Next, the oil ring wire is cut into a required length, coiled so that the ridge is on the outer peripheral side and the substantially circular arc shape is on the inner peripheral side, and hard chrome plating is applied on the outer peripheral surface. The desired oil ring was obtained.

Then, the oil ring obtained according to the present invention was mounted on a cylinder, and a test was carried out on the oil scraping property to evaluate.

As a result, it was confirmed that the oil ring had the same or better oil scraping property as that of a conventional two-piece oil ring.

[0021]

According to the oil ring of the first aspect, the piston contact surface on the inner peripheral side makes a point contact with the piston, and the angle can be freely changed. The followability of the ridge to the cylinder wall is improved,
The oil can be efficiently raked, and the raked oil can be efficiently returned to the lower portion of the cylinder by the oil drop unit. Further, as compared with a conventional two-piece oil ring, a coil expander is not required, the weight can be significantly reduced, and the high-speed rotation of the internal combustion engine and the fuel consumption can be reduced. Manufacturing costs can be significantly reduced. Claim 2
According to the oil ring of the third aspect, the oil scraping property and the property of returning the collected oil to the lower portion of the cylinder can be further improved. Further, according to the oil ring of the fourth aspect, the oil return property can be further improved. According to the oil ring of the fifth aspect, excellent effects can be exhibited in terms of rigidity, oil scraping property, ring workability, followability to the cylinder wall, and stability at the time of installation.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing an embodiment of a piston ring of the present invention.

FIG. 2 shows an embodiment of the piston ring of the present invention,
(A) is a perspective view, and (B) is a perspective view of a main part.

3A and 3B show a conventional piston ring, wherein FIG. 3A is a partially cutaway perspective view showing a used state, and FIG. 3B is a perspective view.

[Explanation of symbols]

 1. . . Piston ring 2. . . Upper ridge 3. . . Lower ridge 4. . . Central ridge 5. . . Piston contact surface 6. . . Oil drop section 7. . . Through hole T. . . Oil ring thickness W. . . Oil ring width h. . . Ridge height t. . . Rib thickness . . Radius of curvature of piston contact surface

Claims (5)

[Claims] 1. A steel oil ring used for a piston of an internal combustion engine, wherein a cross-sectional shape on an inner peripheral side is formed into a substantially circular arc shape bulging outward, and a cross-sectional shape on an outer peripheral side is substantially U-shaped. An oil ring comprising: an upper ring, a lower ridge, and at least one oil drop portion provided on a contact surface of the lower ridge with a cylinder wall. 2. The oil ring according to claim 1, wherein a central ridge is provided between the upper and lower ridges, and at least one or more oil drop portion is provided on a contact surface of the central ridge with a cylinder wall. . 3. The oil ring according to claim 2, wherein the oil drop portions of the central ridge and the lower ridge are provided at upper and lower asymmetric positions. 4. The oil ring according to claim 1, wherein a plurality of through-holes extending from the outer peripheral side to the inner peripheral side are provided in the groove between the ridges. 5. The oil ring has a thickness dimension (T) of 1.5.
5 mm, the width dimension (W) including the ridge is 2-4 mm, and the radius of curvature R of the substantially circular arc shape on the inner peripheral side is R = (1 / 2-3 /
4) T and the thickness (t) of the ridge is 0.5 to 1.0
The oil ring according to claim 1, 2, 3 or 4, wherein the height (h) of the ridge is 0.2 to 0.8 mm.