JPH0752349Y2 - Cylinder and piston ring combination - Google Patents

Description

The present invention relates to a combination of a cylinder and a piston ring used in an internal combustion engine.

“Conventional technology” In conventional cast iron or steel cylinder liners, graphite is finely dispersed in the structure to form an oil sump, so the oil film provides an appropriate sliding surface without interruption, and is often used as a cylinder material. Came. But in recent years high speed,
Since it has poor wear resistance when used in high-load engines, plated cylinders having a hard porous chromium plating on the sliding surface have come to be used.

On the other hand, as a mating material for porous chrome plated cylinders,
The piston ring is coated with a phosphate coating or an iron oxide coating to provide conformability, or is subjected to ferrochrome spraying or nitriding treatment to impart wear resistance. When the cylinder is not plated with porous chrome, a combination of solid or porous chrome plated piston rings has been used.

Further, as a method for further improving the wear resistance of the sliding surface of the cylinder liner, for example, JP-A-52-138797 discloses a method of embedding SiC particles in the sliding surface. Further, in JP-A-61-144469, a cylinder in which hard particles such as SiC and Al ₂ O ₃ are embedded in the sliding inner peripheral surface and a high chrome cast iron powder and Fe-C-Cr alloy in the sliding outer peripheral surface are disclosed. A sliding surface pair structure is disclosed which is formed by a combination of a piston ring obtained by plasma spraying a powder obtained by mixing powder and Mo powder.

Furthermore, as a technique to improve the wear resistance and seizure resistance of the piston ring, the sliding outer peripheral surface is plated with hard chrome, and a TiN coating is formed on it by ion plating (Japanese Patent Publication No. 1-33658). , A nitriding layer is provided on the outer peripheral surface of the slide, and TiN is deposited on the nitriding layer by ion plating.
Those with a coating (Japanese Patent Application No. 59-131878) and those with a Ti (Cx, Ny) coating by ion plating on the sliding outer peripheral surface (Japanese Patent Publication No. 1-52575) have already been proposed. .

"Problems to be solved by the invention" However, in recent years, the performance of internal combustion engines has become higher and higher,
High-speed, high-load products have been developed, and there is a demand for a sliding member that has durability to meet these requirements and that consumes less lubricating oil and fuel. In order to meet these needs, sliding surfaces such as cylinders and piston rings are exposed to harsh conditions, and not only heat resistance, corrosion resistance, and wear resistance, but also weight reduction and oil ring tracking even in piston rings It has become necessary to satisfy both the requirements for heat resistance and seizure resistance.

In such a situation, a cylinder with hard particles such as SiC, Al ₂ O ₃ etc. embedded in the sliding inner peripheral surface shows outstanding performance in terms of wear resistance of the cylinder itself, and it has been applied to steel thin cylinders etc. It is considered to be promising because it has advantages such as weight reduction. However, in the case of this cylinder, there is a drawback in that the mating piston ring is extremely worn, and the present situation is that no combination of piston rings compatible with this has been found yet.

Therefore, an object of the present invention is to provide a combination of a cylinder and a piston ring, which has excellent durability even when applied to a high-speed, high-load internal combustion engine and can reduce the consumption of lubricating oil.

[Means for Solving the Problems] In order to achieve the above object, the combination of the cylinder and the piston ring of the present invention has a cylinder in which hard particles are dispersed and embedded in the sliding inner peripheral surface and a sliding outer peripheral surface. A nitriding layer is formed, and molybdenum nitride (MO
_x N _y ) and a piston ring having a hard coating layer formed thereon.

Hereinafter, the present invention will be described in more detail with reference to specific examples.

In the present invention, the hard particles to be dispersed and embedded in the sliding inner peripheral surface of the cylinder (including the cylinder liner) include Si.
At least one selected from C, Al ₂ O ₃ , Cr ₂ O ₃ , Si ₃ N ₄ and BN is preferably adopted.

When these hard particles are dispersed and embedded in the sliding inner peripheral surface of the cylinder, the hard particles are present at the outermost surface of the sliding surface and become the primary sliding surface, and between the secondary sliding surface of the cylinder surface Since a minute gap is formed in this region and this becomes the oil film forming region, the best lubrication action can always be given. Moreover, since the hard particles are composed of the above ceramic particles, extremely high wear resistance is imparted.

The average particle diameter of the hard particles is preferably 5 to 20 μm, and if it is less than 5 μm, the gap between the primary sliding surface and the secondary sliding surface is too small, which hinders the formation of an oil film. And the secondary sliding surface are too large, and particles may fall off during sliding with the mating material, which is not desirable.

As a method for dispersing and embedding hard particles on the sliding inner peripheral surface of the cylinder, for example, when finishing the inner peripheral surface of the cylinder by lapping, embedding by grinding while spraying a slurry-like liquid containing hard particles. The method of doing can be adopted. This method is described in JP-A-61
-144469 etc. are described in detail.

On the other hand, when the piston ring is combined with the above cylinder, the wear resistance is insufficient with the chromium plating ring which is usually most often used. Therefore, in the present invention, at least the sliding outer peripheral surface of the piston ring is nitrided,
Further, a hard coating layer made of molybdenum nitride (Mo _x N _y ) is formed thereon by PVD treatment.

As the nitriding treatment, any known method such as a gas nitriding method, a salt bath soft nitriding method, a gas soft nitriding method and an ion nitriding method can be adopted. By nitriding, the hardness of the surface becomes Hv600 ~ 1300, depending on the method, and it shows excellent wear resistance.

However, from the compatibility with the cylinder in which hard particles are embedded,
The above nitriding treatment is not sufficient, and it is necessary to further form a hard coating layer made of molybdenum nitride (Mo _x N _y ) on the nitriding treatment. This hard coating layer can be formed by a PVD treatment such as a vacuum deposition method, an ion plating method, and a sputtering method, but in order to prevent the softening and deformation of the piston ring base material, an ion plating method with a low treatment temperature is particularly preferable. It is preferably adopted.

Ion plating method for molybdenum nitride (Mo
_x N _y ) is formed, for example, by irradiating Mo, which is an evaporation source, with an electron beam, and using a high vacuum type ion plating apparatus in which an ionization electrode is provided in the vicinity of the evaporation source, in a nitrogen gas atmosphere. It can be done by

Conventionally, as hard coatings, TiN and TiC coatings have been reported, but TiN coatings have poor compatibility with the mating material, and T
The iC coating has a drawback that peeling easily occurs due to lack of toughness. Compared with this, Mo _x N _y coating has heat resistance and seizure resistance superior to TiN and TiC, has a hardness of about Hv1500, has sufficient abrasion resistance, and has high toughness. It has the property of being difficult to peel off. Moreover, since the coating can be formed at a relatively low temperature, there is an advantage that the piston ring is unlikely to be deformed or softened.

The maximum surface roughness of the sliding inner peripheral surface of the cylinder in which hard particles are embedded is preferably about 2 to 10 μm.
The maximum surface roughness of the sliding outer peripheral surface of the piston ring formed with the Mo _x N _y coating is preferably 3 μm or less.

[Operation] As described above, when hard particles are dispersed and embedded in the sliding inner peripheral surface of the cylinder, the hard particles are present on the outermost surface of the sliding surface and become the primary sliding surface, and the secondary surface of the cylinder surface Since a minute gap is formed between the sliding surface and the sliding surface, this serves as an oil film forming region, which can always provide the best lubrication action. Moreover, the wear resistance of the sliding inner peripheral surface of the cylinder is dramatically improved by the hard particles.

On the other hand, the nitriding layer and
By forming the Mo _x N _y coating, it is possible to impart sufficient wear resistance and seizure resistance as the counterpart material of the cylinder in which the hard particles are embedded. That is, the nitriding layer improves hardness and corrosion resistance, and further Mo _x N
_{When the y} coating is formed, superior wear resistance and seizure resistance can be obtained.

The present invention, by combining such a cylinder and piston ring, imparts durability applicable to a high-load internal combustion engine and also makes it possible to reduce the amount of lubricating oil and the amount of fuel consumed.

[Embodiment] FIG. 1 shows an embodiment of a combination of a cylinder and a piston ring according to the present invention.

In the figure, the cylinder liner 11 is fitted on the inner wall of a cylinder (not shown). A piston 12 is vertically movably inserted into the inner circumference of the cylinder liner 11.
The piston 12 has three annular grooves 13 on its outer circumference, and a piston ring composed of a top ring 14, a second ring 15, and an oil ring 16 is fitted into these grooves 13. The oil ring 16 includes upper and lower rails 18a and 18b and an upper and lower rail 18
It is composed of a steel oil ring having a substantially I-shaped cross section, which is composed of a thin column portion connecting a and 18b and provided with a large number of oil holes, and a coil expander 17 disposed inside thereof.

In the present invention, the layer 19 in which hard particles are embedded is formed on the sliding inner peripheral surface of the cylinder liner 11. In addition, the sliding outer peripheral surface of each piston ring 14, 15, 16 (oil ring 16
In the case of, the nitriding layer 20 is formed on the sliding surfaces of the upper and lower rails 18a, 18b, and the hard coating layer 21 made of Mo _x N _y is formed thereon.
Are formed.

Therefore, when the internal combustion engine operates and the piston 12 reciprocates, the layer 19 in which the hard particles of the cylinder liner 11 are embedded.
And the hard coating layer 21 of the piston rings 14, 15, 16 make sliding contact. In the cylinder liner 11, the wear resistance of the sliding outer peripheral surface is improved by the hard particles, and an appropriate oil film is formed to provide a lubricating action. Also, piston rings 14, 1
With respect to Nos. 5 and 16, the nitriding layer 20 and the hard coating layer 21 improve the wear resistance and seizure resistance of the sliding outer peripheral surface.

Example Inner diameter 100φmm processed to specified dimensions and degreased and washed
× Lapping shoe pressure: 0.8 kg / cm ² , rotation speed × stroke × time on the inner peripheral surface of a cast iron cylinder liner (FC30 equivalent) with a length of 180 mm, using a slurry containing SiC particles with an average particle size of 15 μm. Under the conditions of 60 rpm / min x 30 times / min x 2 minutes,
Simultaneously with lapping, SiC particles were embedded and dispersed in the inner peripheral surface of the cylinder liner.

Separately, steel top ring (SUS420 J2 material, outer peripheral barrel shape, surface roughness 0.5 μm) and steel oil ring (SKD
61 material, I type, surface roughness 0.5μm) was washed with perchlorethylene vapor and set in an electric furnace made of SUS304 steel, and after replacing the air in the furnace with nitrogen, NH ₃ gas was introduced and the furnace was The internal temperature was raised to 570 ° C., and the temperature was maintained for 3 hours for nitriding treatment. The thickness of the nitride layer was 85 μm, but the actual thickness was 70 μm because the highly brittle oxide layer and white layer were removed.

After that, the atmosphere was left to stand in an ion plating tank, the inside of the tank was replaced with argon gas, and then high vacuum was applied, and then nitrogen gas was introduced so that the internal pressure of the furnace was 1 × 10 ⁻³ to 10 ⁻⁵ Torr. Underneath, the ionization was carried out by irradiating molybdenum, which is the evaporation source, with an electron beam to form a hard coating of molybdenum nitride having a thickness of 25 μm.

Comparative Example Steel top ring (SUS420 J2 material, outer peripheral barrel shape, surface roughness 0.5 μm) and steel oil ring (SKD61
Material, I type, surface roughness 0.5 μm) was plated with hard chrome. Hard chrome plating has a top ring of 107μ
m, oil ring 98 μm. These rings were used in combination with the cylinder liner of the above example.

Test Example Using the cylinder liner and piston ring of Examples and Comparative Examples, 4 cycles, 4 water-cooled cylinders, displacement 3600cc, output
It was built into a 110-horsepower diesel engine, and light oil was used to carry out a durability test under a full load of 400 hours.

The results of measuring the amount of wear of the top ring and the oil ring after the test and the amount of wear of the mating cylinder liner at the top dead center position are shown in FIG. The results of measuring the amount of lubricating oil consumed are shown in FIG.

From this result, the combination of the cylinder and the piston ring of the present invention provides less wear of the piston ring even when used in a high-power engine, and has much higher durability than the conventional chrome-plated ring. Also, it can be seen that the consumption of lubricating oil can be significantly reduced.

[Advantage of Invention] As described above, according to the present invention, a cylinder having a sliding inner peripheral surface in which hard particles are embedded, and a hard coating layer composed of a nitriding layer and molybdenum nitride (Mo _x N _y ) are provided. By combining with the formed piston ring having the sliding inner peripheral surface, both the wear resistance and the seizure resistance are improved, and a sliding surface pair structure having good compatibility is obtained. Therefore, even when applied to a high-speed, high-load engine, excellent durability can be obtained, and fuel consumption and lubricating oil consumption can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial sectional view showing an embodiment of a combination of a cylinder and a piston ring according to the present invention, and FIG. 2 is a wear amount of a top ring and an oil ring and a top dead center of a mating cylinder liner. FIG. 3 is a chart showing the result of measuring the wear amount at the position, and FIG. 3 is a chart showing the result of measuring the lubricating oil consumption amount. In the figure, 11 is a cylinder liner, 12 is a piston, 13 is a groove, and 14 is a groove.
Is a top ring, 15 is a second ring, 16 is an oil ring, 18 is a side rail, 19 is a layer in which hard particles are embedded,
Reference numeral 20 is a nitriding layer, and 21 is a hard coating layer made of Mo _x N _y .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Makoto Iezaki 1-9-9 Yaesu, Chuo-ku, Tokyo Inside Teikoku Piston Ring Co., Ltd. (56) Reference JP-A-63-289374 (JP, A) JP Flat 1-182668 (JP, A) Actually open Sho 61-202667 (JP, U)

Claims (3)

[Scope of utility model registration request] 1. A cylinder in which hard particles are dispersed and embedded in a sliding inner peripheral surface, and a nitriding layer is formed on a sliding outer peripheral surface, and molybdenum nitride (Mo _x N _y ) by PVD treatment is further formed thereon. A combination of a cylinder and a piston ring, the piston ring being formed with a hard coating layer made of. 2. The hard particles are SiC, Al ₂ O ₃ , Cr ₂ O ₃ , Si ₃ N.
The combination of a cylinder and a piston ring according to claim 1, which is at least one selected from ₄ and BN. 3. A combination of a cylinder and a piston ring according to claim 1, wherein the hard particles have an average particle size of 5 to 20 μm.