JPS6045268B2 - piston ring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piston ring for an internal combustion engine that requires a high degree of wear resistance.

In recent years, the compression ratio and rotation speed have been increased in order to improve the performance of internal combustion engines.

For this reason, there are inevitably great demands for wear resistance on piston rings. By the way, when classifying wear characteristics,
The phenomena of abrasion (grinding wear caused by high-hardness foreign matter) and scuffing have a major impact on engine performance. Therefore, excellent wear resistance can only be achieved when both abrasion resistance and scuffing resistance work together. Become something to do.

As shown in Japanese Patent Application No. 46-82320, the inventor of the present invention proposes a material that has both abrasion resistance and scuff resistance at the same time. It is characterized by forming a sprayed layer consisting of three phases: 10 to 50% by weight of an unalloyed self-supporting alloy, 20 to 60% of a metal carbide or metal oxide, and the balance of 50% or less of Mo. sliding member.

” and Japanese Patent Application No. 18848/1984, “The alloy wear-resistant layer formed by thermal spraying on the sliding surface of the piston ring is made of molybdenum, chromium carbide, and iron-based alloy, and the analysis value shows that the weight ratio is M030 to 50%, Cr15-60%, C00.
A piston ring comprising 5 to 7.0% Fe, 5 to 20% Fe, and other oxygen and alloy components. ”
provided. However, these previously provided materials themselves have very good wear resistance, and when the mating material is chrome plated, they both exhibit excellent abrasion resistance. It has become clear that especially when the material is cast iron, the highly hard metal carbide or metal oxide dispersed in the structure tends to wear out the cast iron, which is the mating material.

Needless to say, when considering a piston ring, it cannot be used if the mating material, the cast iron cylinder, is worn out. In view of this situation, the purpose of the present invention is to
Not only does it have excellent wear resistance, but
It is an object of the present invention to provide an excellent piston ring that does not cause wear on the mating material. That is, the purpose of the present invention is to provide an iron-based alloy with a weight ratio of mainly 10 to 60% and 10 to 50% on the sliding surface of the piston ring. It is characterized by forming a thermal sprayed layer having a structure consisting of three phases of Mo and 5 to 40% self-storing alloy and pores, and has excellent wear resistance, that is, scuff resistance and abrasion resistance. The purpose of the present invention is to provide a piston ring that satisfies the above-mentioned characteristics at the same time.

The present invention will be explained in detail below.

A feature of the present invention is that a self-fluxing alloy is added to improve the sprayed layer. Examples of self-fusing alloys include Ni-B
-Si system, Ni-Cr-B-Si system, CO-Ni-Cr
-MO (or W)-B-Si system, etc. Self-fusing alloys have a high hardness, some reaching 8C60 or higher, and a hardness of 3 degrees Celsius.
At about 50 degrees, there is no decrease in hardness and the wear resistance and corrosion resistance are excellent. Self-fusing alloys are originally used in a state where they have a very dense structure by fusing after thermal spraying.

In this fusing process, the object to be thermally sprayed is heated to a high temperature of around 1050 degrees Celsius to perform diffusion, so the tension in the piston ring decreases, making it completely unthinkable to use it. However, the inventor discovered that when this self-fusing alloy is plasma sprayed,
They focused on the fact that it has a dense structure even without fusing and can be used as is.

In this case, since the present invention performs plasma spraying, the sprayed layer will inevitably have pores. Next, when this self-fluxing alloy with excellent wear resistance is added to MO, M
The porous structure consisting only of O gradually changes to a dense structure. As is well known, this porous material has oil retaining properties and is therefore very important. However, once MO is oxidized at high temperature, it produces MO oxide, which is
Easily vaporizes at high temperatures, causing oxidative wear. For this reason,
In the present invention, the weight ratio of MO is 50% or less. The decreased component can be compensated for and solved by the ζ-th component added.

That is, one feature of the present invention is the use of an iron-based alloy.

When the MO particles are sprayed onto the Fe surface, they become alloyed with the Fe.

Therefore, it has excellent adhesion to iron-based alloys and is sometimes used as a base treatment for thermal spraying. Further, the bonding force between MO particles and Fe particles is superior to that between MO particles and MO particles. Since the present invention focuses on this point, the term "iron-based alloy" referred to herein refers not only to carbon steel, cast iron, stainless steel, etc., but also refers to iron-based alloys, which is a very general general term. In this way, the MO and Fe particles are firmly bonded to each other, thereby preventing abrasion wear due to shedding of sprayed particles.

At this time, if the content of the iron-based alloy is less than 10% or more than 60%, the bonding force is weak and abrasion wear occurs due to dropout of sprayed particles. Therefore, this Fe-based alloy must be set within a range of 10-10% by weight. Furthermore, due to the coexistence of MO and self-fusing alloys with relatively low-hardness iron-based alloys on the sliding surfaces, minute wear differences occur between MO and self-fluxing alloys and iron-based alloys, resulting in wear. The recessed portion formed by the step is constantly filled with lubricating oil, and the lubricating oil is supplied from the recessed portion onto the sliding surface of the iron-based alloy, thereby improving scuff resistance. If the mixing ratio of MO is less than 10% by weight, there will be insufficient recesses due to wear steps, resulting in a decrease in lubricating oil retention ability.Moreover, MO itself has excellent scuff resistance, and if this MO is 10% If it is less than 50%, it will not be possible to obtain the desired scuff resistance, while if it is more than 50%, MO oxide will be produced when oxidized at high temperature as mentioned above, and this MO oxide will easily vaporize at high temperature, causing oxidative wear. Therefore, MO was set at a weight ratio of 10'' to 50%.If the amount of MO is less than 5%, the wear resistance of the self-fluxing alloy decreases.

In addition, self-fusing alloys have high hardness and poor toughness, and the piston rings are deformed within the cylinder, but this repeated deformation tends to cause cracks in the sprayed layer and make it easy to fall off. Therefore, the content of self-fusing alloy must be 40% or less. As mentioned above, in the piston ring of the present invention, a specific amount of iron-based alloy, MO, and self-fluxing alloy is thermally sprayed on the sliding surface, but since a small amount of alloy layer is formed during thermal spraying, the above components are mainly used, that is, substantially These elements act synergistically to simultaneously satisfy wear resistance, that is, scuff resistance and abrasion resistance. As mentioned above, since a small amount of alloy layer is formed during thermal spraying, the term "mainly" is used in the claims. Next, the present invention will be described in more detail with reference to Examples.

Example 1 A concave groove was formed on the sliding surface of a piston ring having dimensions in the order of outer diameter 83mm x width 2Tn x thickness 3.8, the piston ring was degreased, then heated to 160°C, and plasma sprayed. After that, the sliding surface was smoothed to obtain a piston ring of the present invention.

The sprayed layer at this time was 35% metal molybdenum powder (3μ).
and self-fusing alloy powder (Cl.O%, Sl4.O%, Crl
7. O%, B3.5%, Fe4. O%, balance Ni) 35
% and SK 澹 powder (iron-based alloy powder) (Cl.O%, Sl
O. 2%, MrlO. This is a thermally sprayed layer with a structure of 30% (2% Fe, balance Fe). (Thermal spraying conditions) Plasma device: Metco AM Current, voltage: 80 QA, 35 V Spraying distance: 100 m At this time, the porosity of the sprayed layer was 4.0%, and the hardness was 30-N62.2.

Example 2 Plasma spraying was applied to the sliding surface of a piston ring having the same dimensions as in Example 1 under the same conditions, and then the sliding surface was smoothed to obtain a piston ring of the present invention.

At this time, the sprayed layer consisted of 40% metal molybdenum powder (3 μ) and self-fluxing alloy powder (CO.l 5%, Si 2.5%, Crl).
O. O%, B2.5%, Fe2.5%, balance Ni) 10
% and iron-based alloy powder (C3.5%, MnO.35%, balance Fe) 50% structure, with porosity &
0%, hardness super physical 30-N6O. It was 8. In order to confirm the effects of the present invention, the following tests were conducted. Under the same conditions as described in the example section above, a ductile material was used and a mixed thermal sprayed layer with a porosity of 4.0% and a hardness of 30-N62.2 was applied to the sliding surface.
．． Sample 1 (15-x2 "x7 ugly") with 5 layers formed, porosity 8.0%, hardness super fibrous 30-N62
．． Sample 2 (15
A total of 20m x 7 pieces was created.

Also, for performance comparison, MO3O was added to the sliding surface of the ductile material.
Sample 3 (15 wR x 20
MO43 on the sliding surface of the ductile material
．． 5%, Cr35.9%, Fe2.2%, C3. O%
, porosity 5.5%, hardness super fibrous 30-N6
Sample 4 (15 m
×2h×7]Fl2ll) was created.

Samples 1, 2, 3, and 4 prepared in this way are used as fixed pieces (equivalent to piston rings) using a rotary wear tester, and these fixed pieces are made of cast iron (
C3.2%, Si2. O%, MnO. 8%) (hardness HRB98) (equivalent to cylinder liner) (outer diameter 136 mm, inner diameter 105 T!A, thickness 7 m) is pressed against the upper surface of each ring, and the pressed surfaces are constantly lubricated. The ring-shaped sample was rotated while supplying oil, and the amount of wear after operation was measured.

Test conditions Lubricating oil amount: 0.2 f/Min Lubricating oil: Daphne oil #65 + white kerosene (1:1) Load: 20 kg/Cll Friction speed: 10 rn/Sec Travel distance: 300 - The above test results are shown in Figure 1. As shown.

As is clear from the test results, the wear resistance of Samples 1 and 2 according to the present invention is superior to Samples 3 and 4 for performance comparison, and in particular, the wear resistance of the cylinder liner, which is the mating material of the piston ring, is It can be seen that the product of the present invention is significantly superior to the conventional product. Therefore, based on the above test, it was found that the piston ring of the present invention is also excellent in wear resistance, that is, abrasion resistance and scuffing resistance.

[Brief explanation of the drawing]

Figure 1 shows a graph of the test results.

Claims (1)

[Claims] 1 The sliding surface of the piston ring mainly has a weight ratio of 10 to
60% iron-based alloy and 10-50% Mo and 5-40%
1. A piston ring comprising a thermally sprayed layer having a structure consisting of three phases of a self-fusing alloy and pores.