JPH07158735A - Piston ring of internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent drop of the sealing power when a piston inclines by protruding the upper part of piston periphery toward the cylinder surface. CONSTITUTION:A piston ring of an internal combustion engine consists of a radial portion 30 which is fitted in a ring groove 29 provided at the peripheral surface of the piston 22 and a circumferential portion 33 formed by extending the top 32 till the position of piston 22 top face along the cylinder surface 31, wherein the peripheral surface of the circumferential portion 33 is formed so that its upper part protrudes toward the cylinder surface 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston ring for an internal combustion engine.

[0002]

2. Description of the Related Art A piston ring, which is in sliding contact with a cylinder surface, is mounted on the outer circumference of a piston of an internal combustion engine.

In this piston ring, for example, as shown in FIG. 5, a radial portion 3 fitted into a ring groove 2 formed in the peripheral surface of a piston 1 and an upper end 5 along a cylinder surface 4 are provided on the top surface of the piston 1. There is an L-shaped section having a circumferential portion 6 extending to the position.

This is because the combustion gas pressure is kept at the upper end 5 of the circumferential portion 6.
And the inner circumference 7 and the upper surface 8 and the inner circumference 9 of the radius portion 3,
The gap between the cylinder and the cylinder is sealed, and the volume of the combustion gas remaining around the top surface of the piston 1 is eliminated by the circumferential portion 6 extending to the top surface position of the piston 1 (Actual No. 57-49536). (See gazette, etc.).

[0005]

However, in such a piston ring, since the length of the circumferential portion 6 in the piston axial direction becomes large, when the piston 1 moves up and down, the piston 1 tilts and The piston ring also tilts, but at this time, as shown in FIG. 6, a large gap reaching the lower end of the circumferential portion 6 is formed between the circumferential portion 6 and the cylinder surface 4.

Therefore, there is a problem in that the combustion gas pressure acts on the gap to weaken the sealing force.

The present invention aims to solve such problems.

[0008]

SUMMARY OF THE INVENTION The present invention is a piston for an internal combustion engine, which comprises a radial portion fitted into a ring groove on the piston circumferential surface and a circumferential portion whose upper end extends along the cylinder surface to the piston top surface position. The ring is formed such that the upper side of the outer peripheral surface of the circumferential portion projects toward the cylinder surface.

[0009]

Therefore, since the upper side of the outer peripheral surface of the circumferential portion is in sliding contact with the cylinder surface, the gap between the circumferential portion and the cylinder surface when the piston tilts and the piston ring tilts is the upper part. From the upper end to the lower end of the side sliding contact part.

Therefore, the length of the gap in the axial direction of the piston is shortened (in this case, the gap becomes 0 if the outer peripheral surface of the circumferential portion is tapered from the upper end), whereby combustion gas enters the gap. It is possible to prevent the deterioration of the sealing property.

[0011]

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

As shown in FIGS. 1 and 2, 20 is a crankshaft, 21 is a connecting rod, and a pin 22 is connected to the connecting rod 21 via a piston pin 23 to form a piston 22.
A top ring 24, a piston ring of a second ring 25, and an oil ring 26 are attached to the outer periphery of the.

The top ring 24 has a substantially L-shaped cross section, and a radial portion 30 fitted into a top ring groove 29 formed in a peripheral surface 28 near the top surface 27 of the piston 22 and a cylinder surface. A circumferential portion 33 in which an upper end 32 is extended along 31 to the height position of the top surface 27 of the piston 22.
The upper portion of the outer circumference of the circumferential portion 33 is formed as a convex surface 34 that is in sliding contact with the cylinder surface 31.

The length A of the convex surface 34 in the axial direction of the piston
Is formed to have the same thickness as the radius portion 30, and the height B of the convex surface 34 (the height from the lower side of the outer circumference of the circumferential portion 33) is equal to the circumferential portion even when the piston 22 is tilted to the maximum. The lower end 35 of 33 is formed so as not to contact the cylinder surface 31.

With such a structure, when the piston 22 moves up and down, the top ring 24 tilts as shown in FIG. 3 when the piston 22 tilts (tilt θ). Since the side is the convex surface 34 that contacts the cylinder surface 31, the gap between the upper end (upper end of the convex surface 34) 32 of the circumferential portion 33 and the cylinder surface 31 is short from the lower end of the convex surface 34.

Therefore, even if the combustion gas pressure acts on the gap, it becomes weaker than the pressure from the inner peripheral side of the circumferential portion 33, so that a sufficient sealing property can be secured.

FIG. 4 shows another embodiment of the present invention.
The outer circumference of the circumferential portion 41 of the top ring 40 is formed as a tapered surface 43 that is recessed from the upper end 42 side to the lower end side.

This taper angle θ ₁ is set so that θ ₁ > θ _{2 where} θ ₂ is the maximum inclination of the piston 22. The other structure is the same as that of the above embodiment.

By doing so, the outer peripheral upper end 42 side of the circumferential portion 41 of the top ring 40 becomes a sliding contact portion with the cylinder surface 31, so that the cylinder surface 31 is inclined even if the top ring 40 is inclined as shown in FIG. There is no gap between and.

[0020]

As described above, according to the present invention, the piston of the internal combustion engine is composed of the radial portion fitted into the ring groove of the piston circumferential surface and the circumferential portion having the upper end extended to the piston top surface position along the cylinder surface. In the ring, of the outer circumferential surface of the circumferential portion, the upper side is formed so as to project toward the cylinder surface, so that the gap between the circumferential portion and the cylinder surface when the piston is tilted is sufficiently small, High sealability can be secured, and reliability is improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an engine.

FIG. 2 is a sectional view of a piston ring according to an embodiment.

FIG. 3 is an operation explanatory view.

FIG. 4 is a sectional view showing the operation of another embodiment.

FIG. 5 is a cross-sectional view of a conventional example.

FIG. 6 is an operation explanatory view.

[Explanation of Codes] 22 Piston 24 Top Ring 29 Top Ring Groove 30 Radius Part 31 Cylinder Surface 32 Upper End 33 Circumferential Part 34 Convex Surface 40 Top Ring 41 Circumferential Part 42 Upper End 43 Tapered Surface

Claims (1)

[Claims] 1. A piston ring for an internal combustion engine, comprising: a radial portion fitted into a ring groove of a piston peripheral surface; and a circumferential portion having an upper end extending along a cylinder surface to a piston top surface position. A piston ring for an internal combustion engine, wherein an upper side of the outer peripheral surface projects toward the cylinder surface.