JPH0122924Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an oil ring installed in a ring groove of a piston of a reciprocating internal combustion engine, and in particular relates to a spacer expander and oil rings disposed above and below the spacer expander. The present invention relates to an improvement in a combination oil ring comprising a side rail that is pressed in the outer circumferential direction by an expander and pressed against the inner wall surface of the sill.

In recent years, as the performance of internal combustion engines has improved, great efforts have been made to control lubricating oil and suppress blow-by. Various steel combination oil rings with high surface pressure have been developed. In these combination oil rings, wear of the contact portion between the side rail and the spacer expander serving as a support member is a problem. In the steel combination oil ring that is currently most commonly used and is composed of two upper and lower side rails and a spacer expander, the contact area between the pad of the spacer expander and the inner circumference of the side rail occurs during engine operation. Since it is stationary with almost no movement, significant wear occurs at the contact portion between the two, and as a result, the tension as a combination oil ring rapidly decreases, eventually leading to the loss of its function as an oil ring. This phenomenon is particularly noticeable when high-lead gasoline is used.

Conventionally known countermeasures include applying Cr plating to the outer surface of the spacer expander, and steel combination oil rings with Cr plating applied to the inner and outer peripheral surfaces of the side rails. It is not very effective when using high lead gasoline. Furthermore, since the local contact surface pressure between the pad portion of the spacer expander and the inner periphery of the side rail is high, the Cr plating on this contact portion may cause fatigue failure during engine operation and may peel off. Therefore, it is currently being considered to apply thick Cr plating to the outer surface of the spacer expander as a countermeasure for high-lead gasoline, but the effect cannot be said to be sufficient compared to productivity and cost.

This invention solves the above-mentioned defects and has a relatively simple surface treatment and has wear resistance comparable to that of Cr plating.
The present invention provides a combination oil ring with excellent fatigue resistance and scuffing resistance.

In other words, in a combination oil ring consisting of a side rail and a spacer expander, at least the surface of the spacer expander that contacts the inner circumferential surface of the side rail is provided with a soft nitrided layer or a Cr plating layer as a base, and ion plating is applied thereon. It is characterized by having a TiN or CrN coating.

Embodiments of the present invention will be described in detail below based on the drawings. As shown in FIG. 1, a combination oil ring 1 in which upper and lower side rails 2, 2 and a spacer expander 3 are combined is fitted into a cylinder liner 5 in a ring groove of a piston 6. Therefore, the upper and lower side rails 2, 2 exert a pressing force on the inner peripheral surface of the cylinder liner due to the elasticity of the spacer expander 3. The pad portion 31 of the spacer expander 3 that contacts the inner circumferential surface of the side rail 2 has a soft nitrided layer or
A Cr plating layer is applied, and a TiN or CrN film 4 is formed thereon by ion plating. In this case, the thickness of the TiN or CrN film is preferably 10 μm or less, preferably 2 to 8 μm, in consideration of adhesion. If the film thickness is less than 2μ, it will be less than the roughness of the underlying surface, and the film surface will be uneven, causing pad portion 31 of spacer expander 3.
This is also unfavorable from the standpoint of abrasive wear resistance.

As mentioned above, the pad portion 31 of the spacer expander 3 is made of ultra-hard material such as TiN or
Since the CrN coating 4 is provided, the pad portion 31, which is the contact area between the inner circumference of the side rail 2 and the spacer expander 3, will not wear out even when the internal heat engine is operated under extreme conditions, especially when using high-lead gasoline. Therefore, the pressing force of the side rail 2 against the inner circumferential surface of the cylinder liner 5 can be maintained for a long period of time without causing any damage, which is extremely effective in reducing and stabilizing lubricating oil consumption.

In addition, when forming a TiN or CrN film on the outer surface of the spacer expander, soft nitriding or Cr plating is performed as a base treatment, and then the TiN or CrN film is applied by ion plating, so the base material is strengthened and the TiN film and CrN
Good film adhesion.

In this invention, the inner peripheral surface of the side rail that comes into contact with the TiN or CrN film provided on the outer surface of the spacer expander can be treated with Cr plating, soft nitriding, hardening, SiC dispersed Ni plating, etc. It can produce good effects.

As described above, according to the present invention, it is possible to obtain a combination oil ring with relatively simple surface treatment and excellent wear resistance, fatigue resistance, and scuffing resistance comparable to that of Cr plating.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the combination oil ring of the present invention. Explanation of symbols, 1...Combination oil ring, 2...
…Side rail, 3…Spacer expander, 31…Pad portion, 4…TiN or
CrN film layer, 5... cylinder liner, 6... piston.

Claims (1)

[Claims for Utility Model Registration] (1) In a combination oil ring consisting of a side rail and a spacer expander, at least the surface of the spacer expander that contacts the inner peripheral surface of the side rail is provided with a nitrocarburized layer or a Cr plating layer as an underlying layer. A combination oil ring characterized by having a TiN or CrN film formed by ion plating thereon. (2) The combination oil ring according to claim 1, wherein the TiN or CrN coating has a thickness of 10 μm or less.