JPH0874658A - Piston for internal combustion engine - Google Patents

Abstract

PURPOSE: To enhance performance related to scraping of oil clinging to the wall face of a bore. CONSTITUTION: An oil ring 3 comprises a main portion 4 formed into a C-ring shape and sliding rails 5 to 7 which project, respectively, from the outer peripheries of the upper and lower ends and the outer periphery of the center part of the main portion 4, the main portion and the rails being integrated together. This constitution permits oil clinging to the wall face 9 of a bore to be scraped off by the upper sliding rail 5 and the center sliding rail 6 or by the center sliding rail 6 and the lower sliding rail 7 even if a piston 1 is inclined relative to the direction of the axis of the bore when moving up and down. Therefore, the oil is scraped off by at least two of the sliding rails, resulting in enhanced performance for scraping off the oil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston for an internal combustion engine having an oil ring for scraping off excess oil adhering to the cylinder wall surface of the internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, a piston for an internal combustion engine disclosed in, for example, Japanese Utility Model Publication No. 1-145968 has been proposed. In this conventional technique, an oil ring is housed in a ring groove formed on the outer peripheral surface of the piston via a spring member. This oil ring is integrally formed of an upper sliding contact rail and a lower sliding contact rail which are annular. The upper and lower sliding contact rails are formed to project outward from the outer peripheral surface of the piston, and the tips of the upper and lower sliding contact rails are at the same protruding position. Then, when the piston moves up and down by the crank mechanism, the tips of the upper slide contact rail and the lower slide contact rail slide against the wall surface of the cylinder bore. By this sliding contact, excess oil adhering to the wall surface of the cylinder bore is scraped off.

[0003]

In the conventional piston for internal combustion engine, the upper and lower surfaces of the oil ring are opposed to the upper and lower surfaces of the ring groove over the entire circumference by the spring force of the spring member. Pressed. Due to this pressure contact, no oil passage is formed at the boundary between the ring groove and the oil ring. As a result, the oil rise is suppressed, and the oil consumption is reduced, which is excellent.

However, since there is a clearance between the piston and the bore, the piston moves up and down with a slight inclination (slap). For this reason, if the tip positions of the upper and lower sliding rails are at the same position, only one of the sliding contact rails will contact the wall surface of the cylinder bore and the oil scraping will be performed. ing.
As a result, not only the performance of scraping oil adhering to the wall surface of the cylinder bore decreases, but also the surface pressure of one of the sliding contact rails in sliding contact increases, and the progress of wear on the wall surface of the cylinder bore and the sliding rail of the oil ring. There was a problem of getting faster.

An object of the present invention is to provide an internal combustion engine capable of improving oil scraping performance by effectively sliding an oil ring against a bore wall surface even if the piston is tilted when the piston moves up and down. To provide a piston.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is arranged in an oil ring groove formed on the outer circumference of a piston and slides on a bore wall surface as the piston moves up and down. The oil ring is equipped with an oil ring for scraping off the oil adhering to the bore wall surface.The oil ring is formed in the circumferential direction of the oil ring so that it can be slidably contacted with the bore wall surface and is arranged in the axial direction of the piston. At least three oil scraping parts are provided, and the oil scraping parts located in the center of the oil scraping parts located at both axial ends of the piston are formed to project outward in the radial direction of the piston. Is the gist.

[0007]

According to the present invention, the oil scraping portion located in the middle of the piston in the axial direction and the end in the coaxial direction are arranged even if the piston moves up and down in a state of being inclined with respect to the axial direction of the bore. The oil scraping portion located at the above portion is in sliding contact with the bore wall. Therefore, the scraping property of the oil attached to the bore wall is improved.

[0008]

【Example】

(First Embodiment) A first embodiment of the internal combustion engine piston according to the present invention will be described below with reference to FIGS.

FIG. 1 is a sectional view showing a partially broken piston 1 in the first embodiment, and FIGS. 2 and 3 are enlarged sectional views showing a main part of FIG. An oil ring groove 1 a is formed on the outer circumference of the piston 1, and the oil ring groove 1 a
The oil ring 3 is inserted into the inside of the a via the coil expander 2.
Has been assembled. The oil ring 3 is formed in the shape of a C ring, and its start end and end end are arranged so as to be close to each other. The coil expander 2 is a spring in which a tension coil spring is continuous in an annular shape, and has elasticity in the circumferential direction and the radial direction of the piston 1. And
The oil ring 3 is urged toward the bore wall surface 9 side by the tension of the coil expander 2.

The oil ring 3 has a base portion 4 formed in a C-ring shape, and a sliding contact rail 5 as an oil scraping portion protruding from the outer periphery of the upper and lower ends and the outer periphery of the central portion of the base portion 4.
7 to 7 are integrally configured. Then, the oil attached to the bore wall surface 9 of the cylinder is scraped off by the sliding contact rails 5 to 7. A plurality of oil return holes 8 are formed in the base portion 4 between the sliding contact rails 5 to 7. As shown in FIGS. 2 and 3, the oil return holes 8 are arranged at predetermined intervals along the circumferential direction of the oil ring 3.
Then, the oil scraped off by the sliding contact rails 5 to 7 is returned to the inside of the crankcase of the engine through the oil return hole 8 and the oil passage hole (not shown) formed in the side wall of the piston 1.

In the sliding contact rails 5 to 7, the tips of the upper sliding contact rail 5 and the lower sliding contact rail 7 are arranged at the same protruding position. The tip of the central sliding contact rail 6 is slightly projected to the bore wall surface 9 side from the tips of the upper sliding contact rail 5 and the lower sliding contact rail 7. The upper slide contact rail 5 and the center slide contact rail 6 and the center slide contact rail 6 and the lower slide contact rail 7 have the same distance. It is narrower than the oil ring provided.

A small clearance is provided between the central sliding contact rail 6 and the bore wall surface 9 so that the piston 1 can move up and down. Furthermore, the angle formed by the line connecting the tip of the central slide contact rail 6 and the tip of the upper slide contact rail 5 and the bore wall surface 9 is such that the piston 1 moves to the right with respect to the axial direction of the bore when the piston 1 moves up and down. It is the same as the slap angle θ1 when tilted (slapped) to the right of Fig. 1. The angle formed by the line connecting the tip of the central sliding contact rail 6 and the tip of the lower sliding contact rail 7 and the bore wall surface 9 is:
It is the same as the slap angle θ2 when the piston 1 is inclined to the left side (the left side in FIG. 1) with respect to the axial direction of the bore.

As shown in FIG. 2, when the piston 1 moves up and down with a slight inclination to the right (slap), the tip of the upper sliding contact rail 5 and the tip of the central sliding contact rail 6 are against the bore wall surface 9. Is slid. By this sliding, the bore wall surface 9
Excess oil adhered to is scraped off by the upper and central sliding contact rails 5, 6. When the tips of the upper and central sliding contact rails 5, 6 slide on the bore wall surface 9, the sliding contact rails 5, 6 are reliably pressed against the bore wall surface 9 by the elastic force of the coil expander 2. On the contrary, as shown in FIG. 3, when the piston 1 moves up and down with a slight inclination to the left side, the tips of the lower slide contact rail 7 and the center slide contact rail 6 slide against the bore wall surface 9. To be done. That is, the excess oil attached to the bore wall surface 9 is scraped off by the central and lower sliding contact rails 6, 7. When the tips of the central and lower sliding contact rails 6, 7 slide on the bore wall surface 9, the sliding contact rails 6, 7 are reliably pressed against the bore wall surface 9 by the elastic force of the coil expander 2.

Therefore, even if the piston 1 moves up and down in an inclined state, the oil attached to the bore wall surface 9 can be scraped off by the pair of sliding contact rails 5, 6 or the pair of sliding contact rails 6, 7. it can. Therefore, the performance of scraping off the oil attached to the bore wall surface 9 can be improved. Also,
The slap angles θ1 and θ2 are the upper and lower sliding contact rails 5,
It is possible to improve the oil scraping performance corresponding to each engine by making it easy to prepare a plurality of the protrusions 7 having different protrusion amounts.

Now, as shown in FIG. 5, the conventional example having two sliding rails and the first embodiment will be compared. The slap angle in both examples is θa, the distance between the sliding contact rail and the bore wall surface 9 in the first embodiment is La, and the distance between the sliding contact rail and the bore wall surface 9 in the conventional example is Lb. That is, as shown in FIG. 4, since the sliding contact rail interval of the first embodiment is narrower than the sliding contact rail interval of the conventional example, the relationship between the interval La corresponding to the slap angle θa and the interval Lb is always La <Lb. Is. Therefore, the followability to the bore wall surface 9 is improved, and the ring tension of the oil ring 3 can be reduced. As a result, the surface pressure of each of the sliding contact rails 5 to 7 with respect to the bore wall surface 9 can be reduced, and the wear and friction of the bore wall surface 9 can be further reduced.

(Second Embodiment) Next, a second embodiment will be described with reference to FIGS. However, the description of the same or corresponding structures as those of the above-described embodiment will be omitted and the same reference numerals will be given.

FIG. 6 is a sectional view showing a part of the piston 1 in the second embodiment by breaking it, and FIG. 7 is an exploded perspective view showing a main part of FIG. The oil ring 10 is assembled in the oil ring groove 1a as in the first embodiment. The oil ring 10 is divided into a first ring portion 11 as a main oil ring and a second ring portion 12 as a sub oil ring. Both oil ring portions 11 and 12 are formed in a C ring shape, and the start end and the end thereof are closely arranged to face each other. A plurality of elongated holes 13 are formed at predetermined intervals on the outer periphery of the base portion 11a of the first ring portion 11. Sliding contact rails 14 and 15 as annular oil scraping portions that extend outward are formed to project on the upper and lower outer circumferences of the base portion 11a, and the tip ends of the upper sliding contact rail 14 and the lower sliding contact rail 15 are the same. Is located at the projecting position.

On the inner peripheral surface of the base portion 12a of the second ring portion 12, recessed portions 12b are cut out at the same intervals as the elongated holes 13 of the first ring portion 11, and the outer periphery of the base portion 12a is formed. A center sliding contact rail 16 as an annular oil scraping portion is formed so as to project outward. The base 12a is fitted in the elongated hole 13 of the first ring 11 so as to be vertically movable, and the circumferential end surface of the base 12a and the circumferential end surface of the elongated hole 13 are in close contact with each other. Also,
There is a gap between the upper end surface and the lower end surface of the base portion 12a and the upper end surface and the lower end surface of the elongated hole 13, and the first ring portion 1
1 and the second ring portion 12 are capable of relatively fine movement. The gap serves as an oil return hole 17 surrounded by the outer end surface of the base portion 12a and the inner end surface of the elongated hole 13.

In the state where the first ring portion 11 and the second ring portion 12 are assembled, the tip of the central sliding contact rail 16 is closer to the crank wall surface 9 than the tips of the upper sliding contact rail 14 and the lower sliding contact rail 15. Is slightly projected. That is, as in the first embodiment, on the line connecting the tip of the central slide contact rail 16 and the tip of the upper slide contact rail 14 and the bore wall surface 9.
The angle formed by and is the same as the slap angle θ1 when the piston 1 is tilted to the right. The angle formed by the line connecting the tip of the central sliding contact rail 16 and the tip of the lower sliding contact rail 15 and the bore wall surface 9 is the same as the slap angle θ2 when the piston 1 is tilted to the left.

Then, when the piston 1 moves up and down with a slight rightward inclination (slap), the tips of the upper slide contact rail 14 and the center slide contact rail 16 have a bore wall surface 9
The oil on the bore wall surface 9 is scraped off. At this time, the upper sliding contact rail 14 and the central sliding contact rail 1
6 and 6 relatively move in accordance with the slap angle θ 1. On the contrary, when the piston 1 moves up and down with a slight inclination to the left side, the tip of the lower slide contact rail 15 and the center slide contact rail 1
The tip of 6 is slid against the bore wall surface 9, and the oil on the bore wall surface 9 is scraped off. At this time, the lower sliding contact rail 1
5 and the center slide contact rail 16 relatively finely move according to the slap angle θ2.

Therefore, the piston ring in the second embodiment can improve the scraping performance of the oil adhered to the bore wall surface 9 as in the first embodiment. At the same time, the first ring portion 11 and the second ring portion 12 have a structure capable of relatively fine movement so as to follow the bore wall surface 9 with slap angles θ1 and θ2. Therefore, flexibility corresponding to a wide range of engine speeds or engine load conditions can be obtained.

The present invention is not limited to the above-mentioned embodiments, but may be arbitrarily modified as described below, for example, within the scope not departing from the spirit of the invention. (1) Three sliding contact rails 5 to 7 are provided in the first embodiment, and three sliding contact rails 14 to 16 are also provided in the second embodiment. Other than this, the number of sliding contact rails may be any number as long as it is three or more. In this case, the tip positions of the sliding contact rails located at both ends of the piston 1 in the axial direction have a predetermined slap angle toward the distal end positions of the sliding contact rails located in the middle in the coaxial direction, and are projected toward the bore wall surface 9 side. Is desirable.

(2) The protruding lengths of the sliding contact rails 5 to 7 in the first embodiment and the sliding contact rails 14 to 16 in the first embodiment may be arbitrarily set according to the slap angle. Good.

Although the respective embodiments of the present invention have been described above, technical ideas other than the claims which can be understood from the respective embodiments will be described below together with their effects. (A) In the piston for an internal combustion engine according to claim 1,
At least three oil scraping parts 5, 6, and 7 are pistons for internal combustion engines provided on the outer circumference of a common oil ring 3. With this configuration, the oil scraping portions 5, 6, and 7 can be attached to the oil ring groove 1a at one time, so that the oil ring groove 1a can be easily assembled.

(B) In the internal combustion engine piston according to claim 1, the oil ring 10 is the main oil ring 11
And the sub oil ring 12, the sub oil ring 12 is loosely fitted to the outer periphery of the central portion of the main oil ring 11 in the axial direction of the piston 1, and the main oil ring 1
1, the oil scraping parts 14, 15 are formed on the outer circumferences of both ends of the piston 1 in the axial direction, and the scraping parts 14, 1 of the main oil ring 11 are formed on the outer circumference of the sub oil ring 12.
A piston for an internal combustion engine, in which an oil scraping portion 16 that protrudes outward of the piston 1 diameter more than 5 is formed. According to this structure, the oil scraping portions 14 to 16 of the main oil ring 11 and the sub oil ring 12 flexibly follow the sliding contact with the bore wall surface 9, and thus scrape the oil adhering to the bore wall 9. The productivity can be improved.

[0026]

As described in detail above, according to the present invention,
Even if the piston moves up and down while tilting with respect to the axial direction of the bore, the oil scraping section located at least in the axial center of the piston and the oil scraping section located at the end in the coaxial direction cause the bore Since the oil adhered to the wall surface can be scraped off, the oil scraping performance can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a piston in a first embodiment embodying the present invention in a broken manner.

FIG. 2 is likewise a sectional view of the piston ring when the piston is tilted to the right.

FIG. 3 is likewise a sectional view of the piston ring when the piston is tilted to the left.

FIG. 4 is a graph for similarly comparing the distance between the piston ring and the bore wall surface with respect to the slap angle of the piston.

FIG. 5 is an explanatory view showing a comparison between the piston ring and the bore wall surface in the same manner.

FIG. 6 is a sectional view showing a piston in a second embodiment in a broken manner.

FIG. 7 is a perspective view showing the piston ring in an exploded manner.

[Explanation of symbols]

1 ... Piston, 1a ... Oil ring groove, 3, 10 ... Oil ring, 5, 14 ... Upper sliding contact rail (oil scraping part), 6, 16 ... Central sliding contact rail (oil scraping part), 7, 15 … Lower slide contact rail (oil scraping part), 9… Bore wall surface

Claims (1)

[Claims] 1. An oil ring, which is disposed in an oil ring groove formed on the outer circumference of a piston and which slides against a bore wall surface as the piston moves up and down to scrape off oil adhering to the bore wall surface. The oil ring includes at least three oil scraping portions which are formed in the circumferential direction of the oil ring so as to be slidably contactable with the bore wall surface and arranged along the axial direction of the piston. A piston for an internal combustion engine in which an oil scraping portion located in the center of the oil scraping portions located at both ends is formed so as to project outward in the radial direction of the piston.