KR19980071704A - Piston Rings for Internal Combustion Engines - Google Patents

Abstract

The present invention provides a piston ring in which adequate leakage of the combustion gas is ensured without the need to provide a groove in the outer circumferential surface of the piston ring to suppress the wear of the piston ring, thereby improving the life of the piston ring.

A piston ring 1 for an internal combustion engine comprises a gas-tight engaged cut area 2 consisting of convex portions 21 and recesses 22 engaged with each other at both cuts of the ring 1. Are provided at both cutout portions, and a plurality of shallow and approximately equally spaced leaking grooves 3 are formed on the lower surface 13 or the upper and lower surfaces 12 and 13 of the piston ring, and the grooves 3 are formed in the piston ring. The outer circumferential surface and the inner circumferential surface of each other.

Description

Piston Rings for Internal Combustion Engines

The present invention relates to piston rings for internal combustion engines, in particular piston rings suitable for large internal combustion engines such as for ships or other structures.

The piston ring for mounting on the piston of the internal combustion engine to maintain the pressure in the combustion chamber must be forcibly enlarged so that its inner diameter is larger than the outer diameter of the piston once it is mounted on a predetermined part of the piston. It then comprises one cut, called engaged cuts, so as to be in close contact with the inner wall of the cylinder by radial expansion. However, in the case of so-called pressure rings (hereafter simply referred to as piston rings), such as top rings used in large internal combustion engines for ships or the like, the interlocking cutouts of the piston rings are simply cut off. If cut radially as a portion, the gap of the engagement cut allows the combustion gas to pass through, which causes the pressure drop and heat load to concentrate around the engagement cut. Therefore, in order to prevent the combustion gas from passing in this way, various means have been applied, such as making the cut portion inclined with respect to the axis of the piston or making the cut portion stepped. For example, Japanese Laid-Open Patent Publication No. 175850/1985 discloses an airtight engagement cutout of the prior art piston ring shown in FIG.

In the engagement cutout 2 of the example shown in FIG. 4, the left end face of the ring has a convex (or iron) portion 21 facing toward the right end face of the opposing ring, which is larger than the thickness of the ring. It is thin and narrower than the width of the ring, and the right end surface has opposing concave (or concave) portions 22 such that the convex portions 21 and the concave portions 22 overlap each other and their surfaces are engaged with each other. Are superimposed on one another, which can cause both cross sections to be closer or away from each other, further closing the gap between the upper and lower surfaces 12 and 13 of the piston ring, thereby preventing combustion gases from passing through. In the drawings, reference numeral e denotes the outer periphery of the ring groove of the piston.

Incidentally, a piston ring having an airtight engagement cutout has a disadvantage in that it is relatively easy to wear, and its wearability is dependent on the pressure difference between the upper surface (combustion chamber side) and the lower surface of the piston ring. Therefore, as a means for reducing the pressure difference, a groove extending from the upper surface of the piston ring to the lower surface of the piston ring is formed so that the high-pressure combustion gas flows through the groove in an appropriate amount. Described in 1995.

5 shows a top view of such a piston ring 1. In the figure, reference numeral 2 is similar to that shown in Fig. 4, which represents an airtight engagement cutout having convex portions 21 and recesses 22, and reference numeral 9 denotes a leak groove, The grooves are formed at four positions spaced at substantially equal intervals on the outer circumferential surface of the piston ring as an example.

FIG. 6 is a partial plan view showing the leaking groove 9 of the piston ring 1 and its periphery, and FIG. 7 is a partial side view of the portion shown in FIG. 6. The leaking groove 9 is formed on the outer circumferential surface 11, and is inclined at an angle α (for example, 45 °) with respect to the upper and lower surfaces of the piston ring 1, so that combustion gas is directed to the groove. The piston ring 1 rotates properly when passing through, so that the piston ring 1 is moved relative to the piston to prevent local overheating.

In consideration of the wear amount of the ring, the heat load on the other ring disposed below the ring, and the like, the amount of combustion gas to be leaked can be adjusted by appropriately determining the cross-sectional area size of the leaking groove 9 and the number of grooves.

On the other hand, the piston ring disclosed in Japanese Laid-Open Patent Publication No. 504739/1995 has been recognized for its effect of effectively leaking gas to effectively reduce the amount of wear, but there are problems as described below.

1) In the piston ring, the largest wear is on the outer circumferential surface. However, since the piston ring is formed with a groove on the outer circumferential surface, it is necessary to further turn the depth of the groove in consideration of wear. This has the drawback that the groove becomes weak in the strength of the piston ring and breaks.

2) Appropriate surface treatment such as chromium plating, thermal spraying, etc. is generally performed on the outer circumferential surface of the piston ring in order to improve wear resistance, but the presence of grooves on the outer circumferential surface may cause difficulty in performing the surface treatment. In addition, the adhesive force of the plating layer around the grooves is reduced.

It is an object of the present invention to solve this problem and to provide a new improved piston which facilitates proper leakage of combustion gases and reduces wear of the piston ring.

According to the present invention, a piston ring for an internal combustion engine having an airtight engagement cutout having convex portions and recesses engaged with both cutout portions of a piston ring, the outer circumferential surface of the piston ring and the inner circumferential surface communicating with each other Is characterized in that a plurality of thin, approximately equally spaced leaking grooves are formed. Preferably, such a piston ring comprises a leak groove radially formed in the piston ring.

1 is a bottom view of an embodiment of a piston ring according to the invention,

2 is a partial front view showing part A of FIG. 1;

3 is a schematic diagram showing a piston ring and its periphery in an embodiment of the invention;

4 is a perspective view of a gas-tight engaged cut area of a piston ring of the prior art,

5 is a plan view of a piston ring of the prior art,

6 is a partial plan view of a piston ring of the prior art,

7 is a partial front view of a piston ring of the prior art.

Explanation of symbols for main parts of the drawings

1: Piston ring 2: Hermetic engagement cutout

3: leak groove 12: top surface of piston ring

13: lower surface of piston ring C: cylinder

P: Piston

The invention is described in more detail with reference to the accompanying drawings, in which exemplary embodiments are shown.

1 is a bottom view of an embodiment of the piston ring of the present invention as seen from below, and FIG. 2 is a partial front view of the portion A of FIG. 1 seen from the outside in a horizontal direction. In the figure, reference numeral 1 denotes a piston ring, reference numeral 12 denotes an upper surface of the ring, reference numeral 13 denotes a lower surface of the ring, reference numeral 2 denotes an engagement cutout, and reference numeral (3) is the leak groove of the ring. That is, in the illustrated embodiment, the lower surface 13 of the piston ring 1 is formed with four thin, circumferentially spaced at approximately equal intervals and radially oriented leaking grooves 3. (3) communicates between the inner and outer circumferential surfaces of the ring. The engagement cutout 2 is the same as or similar to the hermetic engagement cutout shown in FIG. 1. The cross-sectional shape and dimensions of the leak groove 3 can be appropriately determined in consideration of the engine specifications, the heat load on the piston ring and the piston, the amount of fuel product depending on the fuel, and the like. In the embodiment shown in Fig. 1, in the case of a piston ring having an outer diameter of 800 mm, a radial thickness of 25 mm and an axial width of 18 mm, the circumferential length of the leak groove 3 is 3 Mm, axial depth is 2 mm, radius at the bottom of the groove is 1.5 mm.

Since the piston ring 1 is easy to expand radially in the ring groove of the piston as described above, a slight gap is formed between the lower surface of the ring groove and the inner circumferential surface of the piston ring. The ring groove also has a slight gap therein in the axial direction of the piston ring. Therefore, in each combustion cycle of the internal combustion engine, the piston ring is pressed against the lower surface of the ring groove by pressurizing the lower surface of the piston ring, particularly at most moments of the explosion stroke, so that a gap occurs in the upper surface of the ring groove.

This condition of the piston ring 1 and its periphery is schematically illustrated in FIG. 3, wherein reference numeral P denotes a piston and reference numeral C denotes a cylinder. The combustion gas leaks from the upper surface of the piston ring 1 to the lower surface of the piston ring 1 through the leaking groove 3 via a gap between the inner circumferential surface of the ring and the lower surface of the ring groove as shown by the arrow. That is, for the function of the combustion gas leaking out, the piston ring of the present invention functions several functions as disclosed in the above-mentioned Japanese Laid-Open Patent Publication No. 504739/1995. On the other hand, since the piston ring 1 according to the present invention has a leaking groove 3 on the lower surface instead of its outer peripheral surface, the leaking groove is not only the strength of the piston ring, but also the plating and thermal spraying applied on the outer peripheral surface of the piston ring. It does not adversely affect the surface treatment such as spraying). In addition, in the piston ring of the present invention, the amount of wear on the lower surface of the piston ring 1 can be estimated not to be larger than the amount of wear on the outer circumferential surface, so that a sufficient application of the cross-sectional area of the leak groove 3 is possible, and therefore, the above-described Japanese publication. All problems with the piston ring disclosed in patent publication 504739/1995 are completely solved.

Therefore, for the reasons described above, the leak grooves 3 function properly even if they are provided on the lower surface of the piston ring 1, but forming the leak grooves 3 on the lower surface and the upper surface of the piston ring has no problem. Forming the leaking grooves 3 on both surfaces is more preferable because it allows the passage for the combustion gas to be maintained at all times regardless of the operation of the piston ring in the ring groove. It is also desirable to form at least two leaking grooves rather than one leaking groove in order to ensure a well balanced leak of the combustion gas. In the case where a plurality of leak grooves are formed, it is highly desirable to arrange the leak grooves at approximately equal intervals in consideration of the position of the engagement cutout. Otherwise, the leak grooves are oriented away from the radial direction in the inclined direction.

Although the invention has been described in detail above, many changes and modifications can be made by those skilled in the art without departing from the spirit and concept of the invention disclosed herein.

According to the present invention, the proper leakage of combustion gas reduces the wear of the piston ring and thus prolongs the life of the piston ring, thereby enabling the effective operation of the internal combustion engine. Moreover, it has an excellent effect of facilitating the surface treatment on the outer circumferential surface of the piston ring and preventing a drop in the adhesion of the surface treatment.

Claims (3)

A piston ring for an internal combustion engine having a gas-tight engaged cut area (2) having convex portions (21) and recesses (22) engaged with both cutout portions of the piston ring, Piston ring, characterized in that formed on the lower surface (13) of the piston ring (1) a plurality of thin, approximately equal intervals of the leak groove (3) communicating the outer peripheral surface and the inner peripheral surface of the piston ring (1) with each other. In the piston ring for an internal combustion engine having an airtight engagement cutout portion 2 having a convex portion 21 and a recessed portion 22 engaged with both cutout portions of the piston ring, Piston ring, characterized in that formed on each of the upper and lower surfaces (12) and the lower surface (13) of the piston ring (1), a plurality of thin, approximately equally spaced leaking grooves (3) communicating the outer and inner peripheral surfaces of the piston ring with each other. The method according to claim 1 or 2, Piston ring, characterized in that each leak groove (3) is formed in the radial direction of the piston ring (1).