JPH0611038A - Piston ring for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a piston ring of which lubricating oil consumption is small even at operation in the early stage and fine scuff is hard to be generated on the sliding face by polishing the outer circumferential face so as to be under a specified value in surface roughness. CONSTITUTION:A piston ring 2 in which a membrane is formed on the surface by chemical vapour deposition method and finish working is performed by a usual method, is loaded in a fixture 3 they are fitted to a rotary device so as to rotate, and a diamond film 1 is pressed against the outer circumference of the piston ring 2 by the use of a pressing jig 4. The outer circumference is worked by pressing the diamond film so as to be under Ra 0.02 in surface roughness, without spoiling the outer circumferential form. By using such a piston ring, initial comformability with the inner wall of a cylinder is improved, friction is reduced, attacking property against the cylinder is curtailed, and sealing ability is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston ring used in an internal combustion engine, and more specifically, the outer peripheral surface roughness of the piston ring.
The present invention relates to a piston ring that is polished to Ra 0.02 or less.

[0002]

2. Description of the Related Art In order to keep airtightness between the piston and the inner wall of the cylinder and to scrape off the lubricating oil from the cylinder wall to prevent it from entering the combustion chamber, it is used by fitting the piston ring into the outer groove of the piston ring. ing. During operation, the piston ring is subject to wear due to heat, pressure and sliding on the inner wall of the cylinder. To avoid damage from them,
Various heat-resistant and wear-resistant materials have been devised for the piston ring.Recently, general heat-resistant materials are plated, or materials coated with nitride or carbide by chemical and physical vapor deposition methods are used. I'm getting to be done.

Since these materials themselves have a rough surface, they cannot be used as it is as a piston ring. Therefore, as a finishing process, the surface of the material is sequentially changed from a rough abrasive to a fine abrasive, a grinding oil and an elastic grindstone. The polishing is repeated by using a fine abrasive, and the surface is finished to be smooth and used as a piston ring. However, in the above finishing process, the surface of the obtained piston ring is still rough, and in the current state of being used as it is, the initial familiarity with the inner wall of the cylinder is poor, and minute scratches are generated on the sliding surface. In addition, it has the drawback of increasing the consumption of lubricating oil during initial operation.

[0004]

DISCLOSURE OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION The present invention provides a piston ring which eliminates the above-mentioned drawbacks of the present piston ring, consumes less lubricating oil even in the initial operation, and does not easily generate a fine scuff on the sliding surface. According to the present invention,
It is a problem to be solved.

[0005]

As a result of various studies for solving the above problems, it was found that the object can be achieved by polishing the surface of a conventionally used piston ring to a roughness of Ra 0.02 or less.

The actual operation of the existing piston ring for an internal combustion engine was carried out, and changes in the surface shape, surface roughness and lubricating oil consumption of the piston ring were measured. The amount of lubricating oil consumed was large at the beginning of operation, but when operating for a long time, especially 100 hours or more, the amount of lubricating oil consumed was significantly reduced compared to that at the beginning of operation, and the top ring of the piston ring Has a barrel face shape, and its surface roughness is Ra0.02.
It was confirmed that the surface was smooth as follows. Therefore, there is a relationship between the shape and surface roughness of the piston ring and the amount of lubricating oil consumed. By controlling the surface roughness of the piston ring to Ra 0.02 or less, the amount of lubricating oil consumed at the beginning of operation is reduced. Thought.

However, in the finishing process, generally, finer abrasive abrasive grains are sequentially selected and the finishing process is carried out. Therefore, in the conventional finishing process, the surface roughness is about Ra0.05. I knew that the limit was to make it smooth, and Ra0.05 was the limit even if the feathering process was performed, and a surface roughness of Ra0.02 or less could not be obtained.

Therefore, as a result of various studies on the abrasives used for finishing in order to obtain a surface having an outer peripheral surface roughness of Ra 0.02 or less, diamond abrasive grain polishing, white alumina grain (WA) or graphite (GC) polishing was conducted. It was confirmed that a surface roughness of Ra 0.02 or less can be obtained by using processing such as a belt. Which of these processes to use is determined by the piston ring material being processed,
For example, with a piston ring material whose surface is Cr-plated or nitrided, WA or GC processing can sufficiently achieve the purpose instead of diamond abrasive grain polishing processing. Further, it is also possible to omit the conventional finishing process and instead directly perform the diamond grain polishing process, the WA process or the GC process. Generally, diamond, WA, etc. are used as abrasives, and GC is used as anti-friction and lubricant, not as used for smoothing the outer peripheral surface as in the present application.

That is, according to the present invention, the piston ring which has been subjected to the conventional finish processing, or the piston ring which has not been subjected to the finish processing is further subjected to diamond abrasive grain polishing, WA or GC processing, and the top ring has a barrel face shape. Then, a piston ring having an outer peripheral surface roughness of Ra 0.02 or less is provided.

By using such a piston ring, initial familiarity with the inner wall of the cylinder is improved, friction is reduced, attack on the cylinder is reduced, and sealing performance is improved.

[0011]

The present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing an outline of diamond abrasive grain polishing processing according to the present invention. Pack the piston ring 2 with a film formed on the surface by chemical vapor deposition and finished by the usual method into 3
The diamond film 1 is attached to the rotation device and rotated, and the diamond film 1 is pressed against the outer periphery of the piston ring 2 using the pressing jig 4. The diamond film is pressed to process the outer peripheral surface roughness to Ra 0.02 or less without damaging the outer peripheral shape. FIG. 2 is a sectional view showing details of the diamond film. Diamond abrasive grains 5 are applied to the surface of the film 7 using an adhesive agent 6, and a commercially available product can be used. The internal combustion engine was operated with the piston ring obtained according to this example installed, and the results of comparison of the time variation of lubricating oil consumption and scuff resistance with the conventional piston ring are shown in FIGS. 3 and 4. It is clear from FIGS. 3 and 4 that the piston ring of the present discovery is superior to the conventional piston ring.

[0012]

EFFECTS OF THE INVENTION By using the piston ring of the present invention, the consumption of lubricating oil in the initial stage of operation can be reduced, friction loss can be reduced, and engine output can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an outline of a diamond abrasive grain polishing process for a piston ring according to the present invention.

FIG. 2 is a sectional view of a diamond film used for diamond abrasive grain polishing.

FIG. 3 is a graph showing a comparison between operating time and oil consumption when the piston ring of the present invention and the conventional piston ring are used.

FIG. 4 is a graph showing scuff resistance when a piston ring of the present invention and a conventional piston ring are used.

[Explanation of symbols]

 1 Diamond film 2 Piston ring 3 Hiring 4 Pressing jig 5 Diamond abrasive grains 6 Adhesive 7 Film

Claims (1)

[Claims] 1. A piston ring for use in an internal combustion engine, the outer peripheral surface roughness of which is polished to Ra 0.02 or less.