JP3299595B2 - piston ring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates also relates to a piston <br/>-ring for an internal combustion engine, it is effective in combination with an aluminum alloy piston, particularly in the high speed of the internal combustion engine.

[0002]

2. Description of the Related Art Phosphating is often performed on piston rings and cylinder liners for internal combustion engines. This is because the phosphate coating is softer than the underlying iron, has non-weldability, oil retaining properties, and exhibits scuffing resistance.
In addition, the phosphate coating performs an initial adaptation effect at a relatively early stage of engine operation.

As shown in FIG. 5, a phosphate film generally has a structure in which the following three layers are laminated from the iron side as a base. Etching pocket layer: A portion 4 where the base material 5 is irregularly etched by the phosphating solution and the base material 5 and the phosphate coating 2A are intricate. Porous layer: A portion 3 which is located on the etching pocket layer 4 and contains fine holes 6 through which gas is removed during phosphating. Crystal layer: relatively dense portion 8 at the top.

[0004] The upper and lower surfaces of the piston ring are usually treated with a phosphate such as manganese phosphate or zinc phosphate.
Generally, the thickness and surface roughness of each of the above layers are in the following ranges. Crystal layer thickness: 1 to 5 µm Porous layer thickness: 0.5 to 3 µm Etching pocket layer thickness: 2 to 8 µm Surface roughness: 3 to 12 µRz

[0005]

If the crystal layer of the phosphate coating on the upper and lower surfaces of the piston ring has large irregularities, this hardness is harder than that of the material of the piston ring groove. The friction coefficient between the piston rings increases, and the surface of the ring groove is attacked and worn. In an extreme case, the abrasion powder adheres to the upper and lower surfaces of the piston ring, causing a problem that the piston ring is fixed to the ring groove. In such a case, the wear of the piston ring itself also increases.

In recent engines, the above danger has been increased because the inertial impact force between the upper and lower surfaces of the piston ring and the upper and lower surfaces of the ring groove of the piston has become larger due to higher speed and higher performance. As a countermeasure against this, initial compatibility,
If the conditions of the phosphating treatment are selected so as to increase the thickness of the porous layer and the etching pocket layer in order to increase the oil retention, the crystal size (surface roughness) of the crystal layer causing the above-described ring groove wear is selected. Also increase proportionally, and the opponent's aggressiveness increases.

Conversely, even if phosphate treatment is selected so that the roughness of the crystal layer is reduced, the oil retention is not sufficient and the coefficient of friction is not so low, so that the wear of the ring groove cannot be reduced.

[0008] The present invention has less wear of the piston ring and piston ring groove and the piston ring is intended to provide Hisage <br/> the piston-ring which can be prevented from sticking to the ring groove surface.

[0009]

According to the present invention, there is provided a piston ring for an internal combustion engine, wherein a phosphate film is formed on at least the upper and lower surfaces of the upper and lower surfaces and the inner peripheral surface. Is composed of a porous layer and an etching pocket layer, and the outermost layer is the porous layer whose surface roughness is
In the range of Saga 0.5～1.5MyuRz, characterized in that the thickness of the porous layer is 0.5 to 2.0 [mu] m, the thickness of the etching pocket layer is 1.0~5.0μm And

[0010]

[0011]

The phosphate coating formed on the piston ring of the present invention comprises a porous layer and an etching pocket layer.
The surface layer is a porous layer containing fine pores. Therefore, the table
Despite its small surface roughness, it has high oil retention and low attack on ring grooves. For this reason, the wear of the piston ring and the ring groove of the piston is small, and the piston ring hardly sticks to the ring groove surface.

In phosphating, the thickness of the etching pocket layer and the thickness of the porous layer are not independently freely controllable. If the thickness of the etching pocket layer of the phosphate coating is less than 1.0 μm and the thickness of the porous layer is less than 0.5 μm, the oil retention, scuffing resistance and abrasion resistance are not sufficient. The thickness of the etching pocket layer is 5.0 μm.
If the thickness exceeds 2.0 μm and the thickness of the porous layer exceeds 2.0 μm, the gap between the piston ring and the ring groove becomes too large after the abrasion of the coating, and the oil retention and scuffing resistance are further improved. The improvement is no more. On the other hand, if the surface roughness exceeds 1.5 μRz, the coefficient of friction increases, and the aggressiveness of the piston against the aluminum alloy as the base material increases.

In the manufacture of the piston ring of the present invention ,
To remove the phosphate coating crystal layer, the crystal layer is partially removed.
Heat treatment at a temperature (230-300 ° C)
Good. The heat treatment time may be about 0.5 to 1 hour.
When the heat treatment temperature is lower than 230 ° C., the crystallization water is not removed. When the heat treatment temperature exceeds 300 ° C., the crystallization water is completely removed.
The coating falls off in powder form. This heat treatment improves the workability of the crystal layer of the phosphate coating to such an extent that the crystal layer can be easily removed by a polishing process such as buffing or belt sander polishing, thereby increasing the productivity.

[0014]

EXAMPLE A base ring having a surface roughness of 0.8 μRz was polished on the upper and lower surfaces of a cast iron piston ring (material: equivalent to FC250), and then subjected to a phosphate treatment shown in Table 1. The phosphate treatment is a manganese phosphate-based coating treatment. The piston ring in Example 1 in Table 1 removed the outermost crystal layer of the phosphate coating. The polishing process for removing the crystal layer was performed by subjecting the piston ring to heat treatment at 250 ° C. for 1 hour and then performing belt sanding.

FIG. 1 shows a piston ring according to the first embodiment shown in Table 1. As shown in FIG. 1A, a phosphate coating 2 is formed on the upper and lower surfaces of the piston ring 1. As shown in FIG. 1B, the phosphate coating 2 is composed of a porous layer 3 and an etching pocket layer 4 formed sequentially from the surface side. The etching pocket layer 4 is a portion where the base material 5 is irregularly etched by the phosphating solution and the base material 5 and the phosphate coating 2 are intricately formed. The porous layer 3 is on the etching pocket layer 4. This is a portion including fine pores 6 through which gas is removed during phosphating. Reference numeral 7 denotes a hard layer such as a hard chromium plating film, a nitride layer, and a PVD film formed on the outer peripheral surface.

With respect to the piston rings having the phosphate coatings shown in Table 1, a test for adhesion of tin plating and fixation to the ring groove surface, and a rotary tapping wear test were performed.

The test of the adhesion of the tin plating and the fixation to the ring groove surface is performed by mounting the piston ring in the ring groove of the tin-plated piston and shrinking the piston ring in the radial direction with a force of 5 to 7 kg. 5 times alternately in clockwise and counterclockwise directions. At this time, it was examined whether the piston ring was fixed to the ring groove surface and whether tin plating was attached to the upper and lower surfaces of the piston ring.

[0018]

FIG. 2 shows a surface roughness load curve for each piston ring shown in Table 1 above. The depth and surface roughness at the 20% and 80% load area ratios, the adhesion of tin plating, and the piston ring FIG. 4 is a diagram showing a relationship between the fixing and the fixing.

The load area ratio in FIG.
(Σl _n / L = 1%)) is the value% of (ｈl _n / L) at a position lower than the depth h. l _n is the outermost surface (Σl _n
/ L = 1%), the width of the peak in the roughness curve at the position where the depth is lower than h, and L is the measured length.

FIG. 2 shows that there is a relationship between the depth at a load area ratio of 20% and the adhesion of tin plating and the adhesion of the piston ring. Is an effective means for improving the surface properties.

Next, a description will be given of a rotary tapping wear test performed between a piston material and a piston ring (a material equivalent to SWOSC-V) subjected to a manganese-based phosphate treatment. An outline of a test performed using a rotary hitting wear tester will be described with reference to FIG.

The tester includes a vertically moving unit 10 and a rotating unit 11 disposed directly below the vertically moving unit 10. The vertical moving unit 10 moves up and down by driving a motor. Rotating part 11
Is clockwise about the vertical axis by motor drive.
After rotating by 80 degrees, the operation of rotating by 180 degrees counterclockwise is repeated. The vertically moving portion 10 is configured such that a disk member 12 made of a piston material (aluminum alloy) can be mounted on a lower end portion and the disk member 12 can be heated to a desired test temperature. The rotating part 11 is configured so that the piston ring 15 can be fixed horizontally on the upper surface thereof. The lower surface of the disk member 12 mounted on the vertically moving unit 10 forms a horizontal plane, and is arranged to face the horizontal upper surface of the piston ring 15 fixed to the upper surface of the rotating unit 11.
A notch 13 is provided on the outer periphery of the disk member 12, and lubrication is performed by supplying lubricating oil to the notch 13 of the disk member 12 from a lubricating oil supply port 14 by a metering pump.

The test is performed as follows. Rotating part 1
1 is rotated, and the vertically moving part 10 is vertically moved. The vertical movement of the vertical movement unit 10 causes the piston ring 1
5 is hit with the lower surface of the disk member 12. In this tester, the number of hits, hit load, reversal speed of the rotating unit 11,
The temperature of the disk member 12 can be changed as appropriate. The striking load is set in a state where the piston ring 15 is pressed against the disk member 12 at the position of the bottom dead center of the vertically moving part 10. The pressing force is applied by compressing a coil spring installed in the rotating unit 11. At this time, the compression amount of the coil spring is detected by the load cell, and the hit load is read by the load meter.

Tables 2 and 3 show the results of wear tests performed on the piston rings on which the phosphate coatings shown in Tables 2 and 3 were formed, using the rotary hitting wear tester. The test conditions are as follows. Hitting load: 55 kg Hitting speed: 700 rpm Inversion speed: 10 cpm Test temperature: 200 ° C. Test time: 5 hours Lubricating oil: Nisseki High Diesel S 3.10 W 0.05 ml / 20 minutes

[0026]

[0027]

[Table 3]

As shown in the above test results, the piston rings in Examples 1 to 5 did not cause the adhesion of Al, and had little wear on the mating member and themselves.

In the above description, the phosphate film composed of the porous layer and the etching pocket layer was formed on the upper and lower surfaces of the piston ring, but the phosphate film composed of the porous layer and the etching pocket layer was formed on the upper and lower surfaces and the inner peripheral surface. Alternatively, it may be formed as follows.

[0030]

As described above, according to the piston ring of the present invention, the wear of the piston ring and the ring groove of the piston on which the piston ring is mounted can be reduced, and the piston ring is fixed to the ring groove surface. Can be prevented.

[0031]

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, in which (a) is a longitudinal sectional view showing a part of a piston ring, and (b) is a view schematically showing a phosphate coating part of the piston ring.

FIG. 2 is a diagram showing the relationship between the depth and surface roughness at a load area ratio position of 20% and a position of 80%, the adhesion of tin plating, and the fixation of the piston ring in the piston rings in Examples and Comparative Examples. is there.

FIG. 3 is an explanatory diagram of a load area ratio.

FIG. 4 is a longitudinal sectional view showing an outline of a rotary hitting wear tester.

FIG. 5 is a diagram schematically showing a phosphate coating portion of a conventional piston ring.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piston ring 2 Phosphate coating 3 Porous layer 4 Etching pocket layer 5 Base material 6 Hole 7 Hard layer

Continuation of the front page (56) References JP-A-2-176269 (JP, A) JP-A-63-235767 (JP, A) JP-A-61-166962 (JP, A) Jpn. , U) Japanese Utility Model Showa 61-55065 (JP, U) Japanese Utility Model Showa 60-82552 (JP, U)

Claims (1)

(57) [Claims] 1. A least a piston ring for an internal combustion engine phosphate coating is formed on the upper and lower surfaces of the upper and lower surfaces and inner peripheral surface, the phosphate coating consists of a porous layer and the etching pocket layer, the outermost The surface layer is the porous layer
The surface roughness is in the range of 0.5 to 1.5 μRz, the thickness of the porous layer is 0.5 to 2.0 μm, and the thickness of the etching pocket layer is 1.0 to 5.0 μm. A piston ring.