JPS585456A - Combination piston ring - Google Patents

Abstract

PURPOSE:To obtain a combination ring excellent with wear resistance and heat resistant settling, by selectively applying a mother material of both steel side rail and spacer expander, when soft nitriding treatment is applied to the side rail and the spacer expander to form the combination oil ring. CONSTITUTION:A combination oil ring consists of side rails 1 and a spacer expander 3, axially and radially supporting the side rail, and a peripheral surface 11 of the side rail is slidably contacted to a cylinder internal peripheral surface 51, further an internal peripheral surface 13 of the side rail is slidably contacted to a protrusion 31 of the spacer expander. Mother material basic composition of the side rail is dispersed with 3-7% fine granular carbide by area ratio of tempered martensite not more than 10mu with hardness of HV1,200-1,500, and a nitriding compound of total hardness HV1,300-1,500 is provided at least 2mu on the surface, while mother material basic composition of the spacer expander is of austenite and provided with a nitriding compound layer of HV800-1,000 at least 2mu on the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oil ring for an internal combustion engine, which is a combination oil ring that combines a side rail made of sil steel and a spacer expander made of steel. As shown in FIG. 1, in this oil ring, two sight rails 1.1 are supported by the spacer expander 3 in the axial and radial directions, and the outer circumferential surface 111 of the horse sight rail and the inner circumferential surface 51 of the cylinder slide into contact with each other. The sight rail inner peripheral surface 13 and the spacer expander protrusion 31 are in sliding contact.

This oil ring is a thin ring with a sight rail of usually 1.0 mm or less, and has flexibility in its radial behavior, which improves its ability to follow the inner circumferential surface of the cylinder and provides an excellent sealing function. . Therefore, to meet the basic requirement of thinning, steel wire rods have to be used, and the mechanical properties of this steel material have various problems when used in piston rings, and improvements are desired. The biggest problem is that under high-temperature conditions such as in a diesel engine, steel material undergoes a so-called heat-settling phenomenon and loses its self-tension. The wear of the panda and the sight rail is extremely large, and measures to prevent wear and tear are required.

Conventionally, in order to solve the above-mentioned problem 1 of piston rings, particularly to improve wear resistance, surface coating such as hard chromium plating and heat treatment such as nitrocarburizing are usually applied. (For example, Japanese Patent Publication No. 15-16502 - Utility Model Publication No. 44-241) However, such surface treatment does not necessarily produce the desired effect, and selection according to the function of the oil ring may be particularly required. The outer circumferential surface of the sight rail is the sliding surface with the inner circumferential surface of the cylinder, so wear resistance is required the most, but if a material containing a large amount of high-hardness carbide is placed here, the inner circumferential surface will have a spacer expander. On the other hand, if the spacer expander is made of a highly hard material, it will be difficult to perform press molding. On the other hand, when the above-mentioned chrome plating is used in combination with a chrome-plated cylinder, wear occurs due to metal-to-metal contact with the same material.Also, in diesel engines 1, high-lead gasoline engines, wear increases due to progressing corrosive wear. was limited.

Oil rings that undergo heat treatment, typically nitrocarburizing, undergo hardening of the red surface and softening of the base material.Although this is effective in preventing thermal deterioration, it is not necessarily sufficient to improve wear resistance. . In other words, even if nitrocarburizing is applied to the site rail and spacer expander, depending on the base material of the spacer expander and site rail, one side may wear out abnormally, making it difficult to obtain the optimal combination. Met.

The present invention provides an oil ring that is a combination of a spacer expander and a sight rail and has extremely excellent wear resistance and heat resistance even under conditions of high temperature and high load.

The present invention will be explained in detail below.

First, the gist of the present invention resides in an oil ring having three primary configurations, as described in the claims.

(1) This is a combination of the following spacer expander and sight rail.

(2) Sight rail: The matrix structure of the base material is martensite with a hardness of 11 and 10 μ or less) IVI! 100-150
0 is dispersed in an area ratio of 3 to 7%, and the surface of the seam has a nitride compound layer of 2 μ or more with an overall hardness of HV1800 to 1600.KMOI-0 to 1-8
%s VO A site rail containing O-07 to O-12% and further having a diffusion layer of 20μ or more under the nitride compound layer.

(3) Spacer expander: Base material of base material is austenite, 1 surface has overall hardness of 3 μ or more, HV80
Spacer expander with a nitride compound layer of G~1000.

The combination of the sight rail and spacer expander of the present invention as described above has the following effects. For members that slide relative to each other, there are various conditions for friction and wear, but in general, the main factors are hardness, the presence or absence of hard materials, and the amount and texture.

In the present invention, the spacer expander is made of round stainless steel with an austenite base structure that is generally used for piston rings.
s96 and below l5i1. O* or less s Mn6.5-7.6
961. Ni8.6-5-54s Cr141, 0-1
8.096s Fe-based austenitic stainless steel containing residual impurity is subjected to nitrocarburizing treatment at 600°C or less and rti o"c or more.The reason for using such a high-Or austenitic steel is its heat resistance. The reason for this is that it has excellent workability in plastic working.When soft nitriding is applied to such austenitic stainless steel, a nitride compound layer is formed on the surface layer, and the surface hardness increases as the overall hardness. HV800 to 1000 is relatively low for a hardened layer of a wear-resistant material.Therefore, it is also clear from the experimental results described later that such a spacer expander can be combined with a sight rail whose inner periphery is chrome plated. However, no significant effect can be obtained.

In the present invention, a remarkable effect can be achieved by combining the austenitic stainless steel spacer expander with a martensitic stainless steel that is nitrocarburized and contains a high carbide content of MO%V. It is something that In other words, since the sight rail is required to have wear resistance on the outer peripheral surface, normally a steel material with many carbides and 1 martensite is used, but when soft nitriding is applied, the base material softens and becomes 1 nitrided. Since only the compound layer has wear resistance, it is necessary to maintain long-term wear resistance by either increasing the thickness of the nitrided layer or by increasing the amount of carbide in the base material. Such materials not only risk embrittlement due to increased nitride layer thickness, but also are too strong for austenitic stainless steel spacer expanders, resulting in significant wear.

In the present invention, a sight rail made of martensitic steel that has been subjected to nitrocarburizing is used as in the past, but by making the carbides finer and having an area ratio of 3 to 7%, the bearing effect due to the carbides can be reduced to the outer periphery. At the same time as holding it on the moving surface, it also has a spacer expander and 9 on the inner peripheral surface.
The wear characteristics can be improved as follows.

As shown in Figure 1, the contact between the spacer expander and the sight rail is not so much sliding as it is close to repeated tapping and abrasion under constant contact conditions. It is thought that in engines where fine combustion residue particles such as these are generated, these fine particles rapidly increase contact surface wear. The wear mechanism is mainly due to the occurrence of minute cracks on the contact surface and the resulting destruction, and it is thought that the hardness of the material as well as the strength from the force exert an influence on the sea wear.

In the present invention, the surface structure of the sight rail is 10μ or less, and the fine carbides are uniformly dispersed, making it possible to prevent cracks from occurring around the carbides. Embrittlement can be prevented by setting the content to 7% or less. On the other hand, the nitride compound layer has a higher hardness than these carbides and exhibits sufficient wear resistance during the initial operation of the engine, which is subject to severe wear conditions. Furthermore, the sight rail of the present invention has the following wear characteristics due to the steel containing % Mos V, that is, % Aos V B acts as a carbide forming element on the one hand. , has strong resistance to softening of the base material due to nitrocarburizing, and can maintain high hardness in the diffusion layer below the nitride compound layer.

Therefore, even after the nitride compound layer is worn away, the diffusion layer has relatively excellent wear resistance, so that it has sufficient wear resistance in an engine that is operated in a steady wear region after the initial wear has finished. This effect is particularly exhibited on the outer periphery of the sight rail, where wear conditions are severe; however, the wear on the inner periphery of a single sight rail is due to the large fatigue factor due to repeated hitting as described above. This has the effect of improving fatigue strength by interposing a highly hard diffusion layer between the nitride compound layer and the base material. The hardness of the nitride compound layer is the overall hardness, and if it is HV1 or more, the spacer expander will wear out significantly, and if it is less than 5HV1!00, the outer surface of the sight rail will be worn out, so HVl50 G -HVI
200f is selected.

Specifically, the sight rail of the present invention has a weight percentage of C0
,85~0.954% Si1.096 or less 1Mn1-
04 or less 5crl, O~19, 0%s Mo
1, O~1. R%s VO-0'1~0.12%Of It is obtained by nitrocarburizing rutinsite stainless steel at a temperature of 1550°C to 600°C. The amount of C is to control the amount of carbide, and if it is less than 0.8596, the amount of carbide is insufficient, and if it exceeds 0.954, it is too much. Cr acts as a carbide forming element and is also used to improve heat resistance and corrosion resistance. MO% V acts as a resistance element against the softening of the base metal depending on the heat treatment conditions associated with nitrocarburizing, and also contributes to the formation of carbides.
) For SMo, the effect is exhibited at 1.04 or more to 0.074 or more for V, and for SMo 1-896% V, no significant improvement in force effect with respect to the added amount can be obtained at more than 0.12%. In addition, if the thickness of the nitride compound layer is less than 3μ for both the trailer spacer and expander, it will wear out during the initial wear, so a thickness of 2μ or more is required. Although it is affected by the thickness of the nitride compound layer and the thickness of the nitride compound layer, the effect will not be exhibited unless the thickness is 30 μm or more. The thickness of the nitride compound layer also depends on the wall thickness of the site rail 1 spacer expander, but if it exceeds about SOμ, 1 embrittlement will be significant.
It is preferable to select a value of 0μ or less.

As described above, the oil ring of the present invention can be used to obtain a combination oil ring with excellent wear resistance depending on the characteristics of the sight rail and the spacer expander. Experimental results are shown below to explain the effects.

The test was conducted using the following engine, which was evaluated based on the amount of wear after actual machine operation.

(Engine used) 2200aa 4-cylinder diesel engine (bore diameter)
Stroke) -81X, 100mm (test conditions) Rotation speed: 40GOrpm Load: 5ops Lubricating oil:
No. 30 oil test time: 100 hours ○ Present invention sight rail (component (weight 4)) C: 0.821Si: 0.42sM
n: 0-38S P: 0-0028sS:
0-008sNi:0-18sCr:17. 2O
S MO: 1゜12SV: 0.141 Remaining Fe (Nitride layer) Compound layer thickness 4.6μm Hardness 1B50 Diffusion layer thickness 22μ (Shape) Inner and outer periphery round edges 9 Thickness 195mm Width
0.6mm 0 Spacer expander of the present invention (components (weight%)) c: o, 08% si:
o, 8s Mn: 6.1% Ni: 4.2s
Cr: 16.5% balance F'e (nitrided layer) compound layer thickness 2.6μm hardness HV950 diffusion layer thickness 12.5μ (shape) radial corrugated spacer expander ○ comparison sight rail 1 (components (weight*) )C:O,F4sSiO-10sMn
:0-12s remaining Fe (Surface treatment) Inner and outer periphery chrome plating thickness 0.15mm Hardness HV920 ○Comparison sight rail 3 (Components) Same as comparison sight rail 1 (Surface treatment) Nitriding Compound layer thickness 6.0 μall 1l
vls o.

○, Comparison sight rail 3 (Components) Same as the present invention sight rail (Surface treatment) None ○ Comparison spacer expander (Components) Same as the present invention spacer expander (Surface treatment) Chrome plating Thickness 0.12 mm 1ytn H'? :
e*.

FIGS. 2 and 3 show the results of testing the above-mentioned sight rail and spacer expander of the present invention and comparison under the experimental conditions described above.

Figure 2 shows the amount of wear (wear depth) of the sight rail and spacer expander 111 contact area. Combine approximately 1/3 to 1/2
It can be reduced to

Next, FIG. 3 compares the abrasion weight of the outer circumferential surface of the sight rail of the present invention.1 It is demonstrated that the sight rail of the present invention is extremely superior in terms of outer circumferential surface wear.

As explained above, and as confirmed through experiments, the combination of the sight rail and spacer expander of the present invention is a combination with extremely excellent wear resistance. It is effective when used in a diesel engine or a high lead gasoline engine.

[Brief explanation of drawings]

Figure 1: A cross-sectional view showing a Nioil ring Figure 2: A diagram showing the results of an experiment comparing the amount of wear between the sight rail of the present invention and a spacer expander Figure 3: A view showing the results of an experiment comparing the amount of wear between the sight rail of the present invention Explanation of figures and numbers shown 1. Site rail 3. Spacer expander 11
1 13 Figure 1 Figure 2 31il Procedural amendment (method) August 1980/Bad Day Commissioner of the Patent Office Kazuo Wakasugi Examiner of the Patent Office 1, Indication of the case 1988 Patent Group No. 14894 2. Name of the invention combination piston ring 3. Relationship with the case of the person making the amendment Patent applicant (f102) Kayo □aAhz fight, ■No. 2. No. 4, Subject of amendment (1) "Combination oil ring" in the third line of page 1 of the specification is corrected to "combination piston ring."

Claims (3)

[Claims] (1) In a combination oil ring made by subjecting a steel sight rail and spacer expander to nitrocarburizing treatment, 1. The nitrocarburized sight rail shown below and the nitrocarburized site rail shown below (7).
A combination oil ring characterized by combining a spacer expander. Sideley/L/: The matrix structure of the base metal is tempered martensite and the hardness is 10μ or less) IV1200 to 150
The surface of the seam has a nitride compound layer with an overall hardness of HV180G to 150G of 2μ or more, and a diffusion layer of Noμ or more below the nitride compound layer. 1 and a weight ratio of 1"Mo1.
Cytorail containing o-i, srs VO-07-0.12%. Spacer expander: The base structure of the base material is austenite, the overall hardness is 2 μ or more on the 91 surface, and HV800 to 1
Spacer expander with 00-0 nitride compound layer. (2) One quantity of the spacer expander is 4 te GO, 15
% or less 5Sil-04 or less s Mn! i, 5~? -5
4-N13. ri-5,64XCrl g, 0-18.
A patented combination oil ring characterized in that it is made of austenitic stainless steel containing 0%s of unavoidable impurities and nitrocarburized at 560°C to 600°C. (3) The side rail has C0.85 to 0 in weight%;
11 596% Sit. 096 or less 1Mnl. 04
Below % Orl 7, 0-1 9.096s Mol.
O~1.84s VO. 550 to martensitic stainless steel containing 07~0-124% balance unavoidable impurities
The combination oil ring according to claim 1 or 2, characterized in that it is soft-nitrided at 0 to 600°C.