JPS5920860B2 - Combination oil ring and piston ring combination for internal combustion engines - Google Patents

Description

[Detailed description of the invention] The present invention relates to a piston ring for an internal combustion engine.

Piston rings arranged between the piston and the cylinder inner wall are generally divided into a compression ring for preventing gas leakage and an oil ring for scraping off excess oil from the cylinder inner wall. For example, in the case of an automobile engine, two or three compression rings and one or two oil rings are generally arranged in combination for each piston. These piston rings must always be in pressure contact with the inner wall of the cylinder in order to function, and therefore it is particularly important to minimize wear on the ring sliding surfaces. One of the causes of increased oil consumption is piston ring wear.

In other words, the increase in oil consumption is particularly noticeable when using high-lead gasoline, but the cause is a decrease in piston ring tension due to piston ring wear, resulting in a significant decrease in oil scraping ability. It has been confirmed that this is the cause. Also, among the wear and tear on piston rings, the combination oil that consists of a pair of upper and lower side rails and an expander member (spacer expander or coil expander, hereinafter the same) for pressing these side rails against the cylinder inner wall It has also been found that the wear on the inner and outer circumferential surfaces of the side rails of the ring is more significant. In view of this, the present invention aims to reduce the wear of the piston rings as much as possible even when using high-lead karyrin as described above, thereby solving the problem of rapid increase in oil consumption caused by the wear of the piston rings. It is something.

To achieve this objective, according to the present invention, the inner circumferential surfaces of both side rails of the combination oil ring are plated with chrome, while the outer circumferential sliding surfaces are coated with ferrochrome or a sprayed layer containing ferrochrome. Then, the outer circumferential surface of the expander member that contacts the inner circumference of the side rail is subjected to soft nitriding treatment.

Furthermore, the present invention also covers a combination of a combination oil ring as described above and at least one compression ring. A single sprayed layer of ferrochrome or a mixed sprayed layer containing ferrochrome is formed on the outer peripheral sliding surface of the shock ring.

In the present invention, the surface treatment of the compression ring is not specified at all, and any commonly used surface treatment may be applied as long as it does not result in at least an increase in oil consumption. Alternatively, it is also possible not to perform surface treatment on unspecified compression rings. Conventional surface treatments for the sliding surfaces of compression rings include chrome plating, phosphate coating, iron composite plating, nickel-phosphorus composite plating, nitriding, and laser annealing. Alloy inks produced by hardening and laser hardening are known. Hereinafter, examples of the present invention will be shown and the effects thereof will be explained in detail.

FIG. 1 shows a steel combination oil ring arranged between the cylinder inner wall 1 and the ring groove 4 of the piston 3. FIG.

The combination oil ring is a pair of upper and lower side rails 5A and 5.
B and a spacer expander 7 that separates these side rails in the axial direction and presses them against the inner wall of the cylinder. According to the present invention, chrome plating 2A, 2B is applied to the inner peripheral surfaces of the upper side rail 5A and the lower side rail 5B, while the ferrochrome sprayed layer 6A is applied to the outer peripheral sliding surface.
, 6B are formed.

Further, the outer peripheral surface of the spacer expander 7 that contacts the inner periphery of each side rail is subjected to soft nitriding treatment (not shown). This soft nitriding treatment is not limited to the Toughtrade treatment, but may also be a persulphur-nitriding treatment, an ion nitriding treatment, or the like. In this way, the contact surface between the side rails 5A, 5B and the cylinder inner wall (
A wear-resistant hardened layer is formed on the sliding surfaces) and the contact surfaces between the side rails 5A, 5B and the spacer expander 7. In addition, in the present invention, the ferrochrome sprayed layers 6A, 6B
may be a sprayed layer containing ferrochrome alone or a mixed sprayed layer mainly composed of ferrochrome, for example, a mixed sprayed layer containing two or more of ferrochrome, a self-fluxing alloy, molybdenum, and stainless steel.

The same applies to the following description. Preferably, as shown in FIG. 2, the outer peripheral surface, that is, the sliding surface, of the compression ring 8 disposed in another ring groove 4' of the piston 3 is also sprayed with ferrochrome similar to the ferrochrome sprayed layers 6A and 6B. Layer 10 is formed.

When two or more compression rings are provided, ferrochrome or a thermally sprayed layer containing ferrochrome may be formed on all the compression rings, or a ferrochrome thermally sprayed layer may be formed only on the first compression ring, and the other The sliding surface of the compression ring may be plated with chrome.

Furthermore, the same effect can be expected by applying a phosphate coating treatment (including a triiron tetroxide coating treatment having the same effect) instead of the chromium plating applied to the compression ring.

Although the piston ring combination of the present invention is primarily used in engines using high-lead gasoline, the present invention is of course also applicable to engines using unleaded gasoline or low-lead gasoline.

Moreover, it can be applied not only to gasoline engines but also to diesel engines. The combination oil ring shown in FIG. 3 is commonly used for diesel engines, and the upper and lower side rails 15A, 15B are integrated, and the spacer expander shown in FIG. 1 is a coil expander 17.
has been replaced by The body of the combination oil ring of FIG. 3 is generally made of cast iron. In this case as well, chrome plating 12A, 12B is applied to the inner periphery of the upper side rail 15A and lower side rail 15B, just as in the case of FIG. Further, on the outer peripheral sliding surfaces of the side rails 15A and 15B, a thermal sprayed layer 16A containing ferrochrome or ferrochrome,
16B is formed. On the other hand, coil extract bander 1
The area around 7 is subjected to soft nitriding treatment. The experimental results are shown below.

0-'ν piston ring configuration: Tables 1 and 2 Cylinder: F
C25 equivalent material (both Examples 1 and 2) In Table 1, high carbon ferrochrome powder (
The ferrochrome sprayed layers 6A and 6B were formed by plasma spraying (average particle size of 250 mesh or less) and used for the black 1 and black 3 cylinders (Example 1), and for the black 2 and black 4 cylinders for comparison. Therefore, using a side rail with hard chrome plating applied to the outer peripheral surface (Comparative Example 1), we compared the wear of the piston ring for each cylinder, and also compared the wear of the piston ring for each cylinder. The effect on ring wear was investigated.

The results are shown in Table 3, and for each cylinder (by surface treatment).
Table 4 shows the average wear amount of each. Note that the amount of wear is calculated from the amount of increase in the abutment gap and is expressed by the following formula.

In addition, the spacer expander of the combined oil ring was treated with Toughtrade for each cylinder.

Next, as shown in Tables 3 and 4, good results were obtained when a ferrochrome sprayed layer was applied to the outer peripheral surface of the side rail of the combination oil ring.
The same piston ring combination (comparative example 2) as in Example 1 in Table 1 was used for black 2 cylinders, and black 3 and f
). For cylinder 4, the same high carbon ferrochrome sprayed layer was formed on the first compression ring under the same conditions as above, and the other compression ring configuration was the same as in Example 1 (Example 2). ) was used in an experiment (
(Table 2), the wear of the piston rings of each cylinder was compared based on the difference in the surface treatment of the first compression ring.

The results are shown in Table 5, and the average wear amount for each cylinder (by surface treatment) is shown in Table 6. In this case as well, the spacer expander of the combined oil ring was treated with Toughtrade for each cylinder.

From the above experimental results, the following was confirmed.

(1) Of course, at the initial break-in stage, durability 10
Even after 0 hours of decomposition, there was no tendency for scuffing and the surface condition of the ring and cylinder was good. (2) When a ferrochrome sprayed layer is formed on the outer circumferential surface of the side rail of the combination oil ring (this invention), the amount of wear after 100 hours of durable operation is drastically reduced to about 1/3 of that when chrome plating is applied in the comparative example. ing.

Also, although it was not shown in the table above, the amount of wear from the intermediate measurement after 50 hours of operation (after the break-in operation) to 100 hours later was approximately 25μ/50Hr when chrome plating was applied. On the other hand, in the case of the present invention in which ferrochrome was applied, the amount of wear was about 1/12 at about 2μ/50Hr, and a significant improvement effect on steady wear was recognized.

(3) In the case of Example 1, not only the wear of the side rails of the combined Oril ring was reduced, but also the side rails of the first and second compression rings were approximately 78% and 91% of that of Comparative Example 1, in which the side rails were plated with chrome. % of each wear amount has been reduced.

(4) In Example 2, when both the first compression ring and the side rail of the combination oil ring were thermally sprayed with ferrochrome, the wear of the first and second compression rings and the side rail was only on the side rail. 67% and 5% of wear, respectively, when ferrochrome was sprayed on
It decreased to 7% and 74%.

(5) Regarding the surface conditions of the cylinders, compare cylinders ▲2 and ▲4 (side rail outer circumferential surface; chrome plating)
In the case of ▲1 and ▲3 cylinders with the piston ring configuration of the example (side rail In the case of the outer peripheral surface (ferrochrome sprayed), such a phenomenon was hardly observed and the surface was in a clean state.

This result was almost the same in both Examples 1 and 2. As described above, according to the present invention, it is possible to significantly reduce not only the wear of the side rails of the combination oil ring itself, but also the wear of the first and second compression rings in the same cylinder. It will be understood that this has the following effects.

Further, when both the compression ring and the side rail of the combination oil ring are coated with ferrochrome or a thermally sprayed layer containing ferrochrome, the wear of each piston ring is further reduced. Therefore, even under the adverse conditions of using high-lead gasoline, wear on each piston ring can be significantly reduced and oil consumption can be stabilized at a low level. In the present invention, the ferrochrome or the sprayed layer containing ferrochrome exhibits considerable adhesion to the base material by itself, but in some cases, a known base treatment such as nickel aluminate may be applied.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a combination oil ring used in the present invention, FIG. 2 is a cross-sectional view of a compression ring used in the present invention, and FIG. 3 is an example of a combination oil ring different from that in FIG. A sectional view shown. 1...Cylinder inner wall, 2A, 2B...
・Chrome plating, 3...Piston, 5A, 5B
, 15A, 15B...Side rail, 6A, 6
B... Ferrochrome sprayed layer, 7, 17...
...Expander parts.

Claims (1)

[Scope of Claims] 1. A combination oil ring for an internal combustion engine consisting of a pair of side rails and an expander member for pressing the side rails against the inner wall of the cylinder, in which the inner peripheral surfaces of both side rails are coated with chrome. In addition to plating, a ferrochrome single sprayed layer or a mixed sprayed layer containing ferrochrome was formed on the outer circumferential sliding surface, and nitrocarburizing was performed on the outer circumferential surface of the expander member that contacts the inner circumference of the side rail. Features a combination oil ring for internal combustion engines. 2. In the combination of a combination oil ring consisting of a pair of side rails and an expander member that presses the side rails against the cylinder inner wall, and a piston ring consisting of at least one compression ring, the compression ring closest to the combustion chamber. A single ferrochrome sprayed layer or a mixed sprayed layer containing ferrochrome is formed on the outer peripheral sliding surface of the combination oil ring, and chrome plating is applied to the inner peripheral surface of both side rails of the combination oil ring, and ferrochrome alone is sprayed on the outer peripheral sliding surface. A combination of piston rings for an internal combustion engine, characterized in that the outer peripheral surface of the expander member that contacts the inner periphery of both side rails is subjected to soft nitriding treatment.