JPS6154862B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a side rail for an oil ring, and particularly to a side rail for an oil ring that is most suitable for application to an internal combustion engine. In recent years, internal combustion engines are increasingly required to have higher performance, higher output, and faster speeds.In addition, they must also be equipped with exhaust gas countermeasures, and there is a need for countermeasures to the problem of increased fuel consumption due to decreased horsepower of internal combustion engines. is increasing. Regarding these problems, the pressure ring and oil ring that maintain the airtightness of the combustion chamber of the internal combustion engine and the lubricity between the piston ring and the cylinder wall have a large impact on the performance of the internal combustion engine, and measures are especially necessary. I'm getting used to it. Oil rings for internal combustion engines have changed from conventional single cast iron rings to combination rings composed of side rails and spacer expanders. This oil ring adjusts the amount of lubricating oil between the sliding piston ring and the cylinder wall, and scrapes off excess lubricating oil so that it does not enter the combustion chamber.This oil ring improves the performance of internal combustion engines and reduces exhaust gas. It also plays an important role. Conventionally, carbon steel has been used for side rails for oil rings, but its low strength at high temperatures limits the ability to make it thinner. Furthermore, due to the lack of heat resistance and abrasion resistance, the sealing properties of the lubricating oil were poor, and there was a problem in that ideal oil control was not possible in terms of exhaust gas countermeasures. The present invention was made in view of these problems, and has superior strength at high temperatures, heat settability resistance, and wear resistance than conventional oil ring materials.
An object of the present invention is to provide a side rail for an oil ring that allows the side rail to be made thinner, maintains good sealing properties, and achieves exhaust gas countermeasures in addition to high output and high speed of an internal combustion engine. In other words, the present invention has an alloy composition in weight%.
C0.6~0.7%, Si0.15~0.4%, Mn0.6~0.8%,
Using martensitic stainless steel containing 12 to 14% Cr, with the balance consisting of Fe and impurities, Cr carbide is precipitated and distributed in area% of 5 to 13% in the heat treatment state, and at least on the sliding surface that slides on the cylinder wall. This is a side rail for oil rings that has a surface treatment layer such as Cr plating or nitriding, and has high strength at high temperatures, as well as good heat resistance and wear resistance. The oil ring according to the present invention will be described below. FIG. 1 is a partial sectional view of an internal combustion engine incorporating a piston ring, and FIG. 2 is a perspective view of a combined oil ring. 1 is a cylinder, 2 is a piston, 3 and 4 are pressure rings, 5 is an oil ring,
6 and 7 are side rails, and 8 is a spacer expander. FIG. 3 shows a perspective view of the side rail, and FIG. 4 shows a partial sectional view of the side rail. 9 is an abutment gap, 10 is an outer circumferential surface, and 11 is a surface treatment layer on the outer circumferential surface. The side rails 6 and 7 for oil rings of the present invention are made of martensitic stainless steel with an alloy composition having the components described below, and at least the outer periphery of the surface of the side rail, which is the sliding surface of the side rail that slides on the cylinder wall. It has a surface treatment layer 11 on the surface 10. The reasons for limiting the composition of the side rail material for oil rings of the present invention will be described below. C imparts high strength and wear resistance, and for this purpose it is necessary to contain at least 0.6%. However, if the C content is high, bending workability will be poor and ring forming will be difficult, so 0.7%
was set as the upper limit. Si has the effect of increasing thermal settability and wear resistance, and must be at least 0.15%. However, if it is in excess, it impairs the plating properties and the workability at room temperature, so the upper limit is set at 0.4%. Mn is contained as a deoxidizing agent and at the same time has the function of changing the form of sulfide, so 0.6% or more is required in order to obtain an appropriate form of sulfide as a side rail material. However, like Si, excessive content impairs plating properties, so the upper limit is set at 0.8%. Cr combines with C to form carbide, which increases heat resistance, corrosion resistance, and seizure resistance. In addition, when nitriding the side rail surface treatment layer, Cr combines with N to form nitrides and forms a hardened layer on the surface layer, which is very effective in improving wear resistance, but there is too much This decreases heat treatment stiffness and deteriorates moldability, so it is limited to 12 to 14% in relation to the C content. In the present invention, the above-mentioned predetermined amounts of C and Cr are added, heated to 1000 to 1100°C, and then rapidly quenched to 550°C.
Tempering at ~650℃ to form Cr carbide in area% of 5~13
% precipitated composition, and at the same time, the parts of the side rail that require wear resistance and seizure resistance, that is, the sliding surface of the side rail that slides on the cylinder wall, must have at least a hard surface with good seizure resistance. A processing layer 11 is provided. As the surface treatment, various surface treatments other than hard Cr plating, special alloy thermal spraying, and nitriding can be appropriately applied. In particular, when the surface treatment layer is a nitride layer, the sliding surface of the side rail that slides on the cylinder wall will be rough.
It has a high Hv of 800 or more, a low coefficient of friction, and excellent wear resistance, seizure resistance, and corrosion resistance, so it exhibits good airtightness as a sliding surface for side rails. Furthermore, as described above, the side rail of the present invention exhibits excellent functions as a side rail because it works in conjunction with the properties of the side rail itself, such as excellent heat settability resistance and high temperature tensile strength. Furthermore, it is necessary that at least the sliding surface of the side rail outer circumferential surface that slides on the cylinder wall has a surface treatment layer.Therefore, it is necessary to provide a surface treatment layer on the upper and lower surfaces of the side rail at the same time as the outer circumferential surface. Of course, this is a good thing. Next, the effects of the present invention will be explained using examples. Table 1 shows the chemical compositions of the side rail of the present invention and the conventional side rail. Further, Table 2 shows the comparison results of the characteristics of the present invention and the conventional side rail after heat treatment. Heat resistance is the load required to bend a 5φ x 150 round bar to a radius of curvature of 25R at room temperature, and the rate of decrease in the load required to bend a 5φ x 150 round bar to the same radius of curvature after heating it at 300°C x 1H in a 25R bent state, returning it to its natural state and bending it again to the same radius of curvature. The lower the rate of decrease, the better the resistance to heat set. Abrasion resistance was measured using an Okoshi type rapid abrasion tester (matching material:
The specific wear amount is shown for annealed SCM21 material, friction distance: 400m, final load: 6.8Kg, friction speed: 1.34m/sec). (Specific wear amount represents the wear volume per unit contact area and unit friction distance)

【table】

[Test institution]

Engine: Gasoline engine Model: Water-cooled 4-cycle Inner diameter x Stroke: 85mmφ x 1770mm Maximum output: 105PS/5400r.pm Maximum torque: 16.5g-m/3600r.pm [Operating conditions] Full/5700r.pm 200 hours continuous operation [ Fuel] Leaded gasoline (3.2gr/usgal) The results are shown in Figure 5, and the wear on the inner circumferential surface of the side rail where it contacts the spacer expander and the wear on the top and bottom surfaces of the side rail are lower than that of the conventional side rail. It was confirmed that it exhibits extremely superior wear resistance compared to rail. In addition, the spacer expander combined with the side rail of the present invention has less than half the wear of the protruding parts of the spacer expander than the spacer expander combined with the conventional side rail, and the amount of wear is less than half of that of the spacer expander combined with the side rail of the present invention. It was also confirmed that it exhibited favorable performance. As described above, the side rail of the present invention has excellent heat resistance and abrasion resistance on the upper and lower surfaces, and has excellent airtightness, seizure resistance, breakage resistance, etc. as a side rail, as well as the axial width dimension of the side rail. This makes it possible to reduce the contact area on the cylinder wall, reduce friction loss, improve the efficiency of the internal combustion engine, and also improve exhaust gas control effects.

[Brief explanation of the drawing]

Fig. 1 is a partial cross-sectional view of an internal combustion engine incorporating a piston ring, Fig. 2 is a partial perspective view of an oil ring consisting of a combination of a side rail and a spacer, and Fig. 3 is a perspective view of the side rail of the present invention. 4
The figure is a partial sectional view of the side rail, and FIG. 5 is a graph showing the test results. 1: cylinder, 2: piston, 3, 4: pressure ring, 5: oil ring, 6, 7: side rail, 8: spacer expander, 9: abutment gap, 10: outer peripheral surface, 11: surface treatment layer.

Claims (1)

[Claims] 1% by weight: C0.6-0.7%, Si0.15-0.4%,
The side rail is made of stainless steel consisting of 0.6 to 0.8% Mn, 12 to 14% Cr, and the balance is Fe and impurities.It has a surface treatment layer on at least the sliding surface that slides on the cylinder wall, and has excellent heat resistance and wear resistance. Side rail for oil ring.