JPH0322538Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a piston ring for an internal combustion engine, and more specifically to a piston ring whose sliding surface is subjected to composite plating.

Conventionally, many piston rings have a wear-resistant chrome plating layer formed on their sliding surfaces, but this chrome plating has a limited durability, and long-term operation can cause wear and tear not only on the ring itself but also on the cylinder bore. It is unavoidable that this will occur. FIGS. 1A to 1D show the state of wear in the top ring and in the cylinder bore near the piston top dead center (TDC). In the initial stage, as shown in FIG. 1A, the sliding surface 2 of the piston ring 1
Both cylinder bore 3 and cylinder bore 3 are not worn,
Thereafter, the area near the top dead center of the cylinder bore 3 begins to wear (FIG. 1B), and as this progresses, the amount of wear on the upper edge of the sliding surface 2 also increases (FIG. 1C). When the piston is further operated, the wear of the cylinder bore 3 develops to a point considerably below the top dead center, and near the top dead center, the cross-sectional shape of the cylinder bore 3 becomes a stepped shape that matches the shape of the sliding surface 2 of the piston ring 1. (Figure 1D).

When the amount of wear on the sliding surface 2 and the cylinder bore 3 increases in this way, the sealing performance between them deteriorates, blow-by gas increases, and the amount of engine oil consumed increases.

If we consider the causes of wear on the sliding surface 2 and cylinder bore 3, there is a lack of engine oil near the top dead center of the piston, and boundary lubrication because the direction of motion of the piston ring changes and the speed becomes 0. This is because the lubricating ability is extremely reduced. That is, especially the upper part of the sliding surface 2 of the piston ring 1 suffers from a lack of oil, resulting in significant wear, and at the same time, stepped wear occurs in the cylinder bore 3.

In view of the above points, the present invention was developed with the aim of reducing the wear on the sliding surface of the piston ring and the cylinder bore, and contains a self-lubricating agent or anti-wear agent in the upper part of the sliding surface of the piston ring. The composite plating layer is characterized in that the density of the self-lubricating agent or anti-wear agent in the composite plating layer is relatively high on the sliding surface side.

The present invention will be explained below with reference to illustrated embodiments.

FIG. 2 shows a first embodiment of the present invention, in which the upper edge side of the outer periphery of the ring member 4 is notched over the entire circumference, and a composite plating layer 6 is formed within the notch 5. This composite plating layer 6 has a self-lubricating agent or anti-wear agent embedded therein either directly or in the form of microcapsules wrapped in a polymer film.
After plating, it is polished to form the cross-sectional shape as shown in the figure.

Examples of self-lubricants include solid lubricants such as graphite, molybdenum disulfide, and graphite fluoride; examples of anti-wear agents include oil-based agents such as stearic acid and lauric acid, or sulfides and chlorides. , polar lubricants such as phosphates. Among these self-lubricating agents or anti-wear agents, those that are solid and do not react with the plating metal may be directly embedded in the plating layer 6, but those that are liquid or react with the plating metal may be embedded directly into the plating layer 6. is embedded in the plating layer 6 in the form of microcapsules wrapped in a polymer membrane. As a method for this microencapsulation, for example, an interfacial polymerization method is known, and is described in JP-A-54-69531.

Furthermore, the self-lubricating agent in the composite plating layer 6 formed in the notch 5 of the ring member 4 is applied to the sliding surface 2.
The density is higher towards the sides. In order to vary the density of the self-lubricating agent depending on the location, the time during which the self-lubricating agent, etc. suspended in the plating liquid stays on the surface of the plating liquid can be changed by changing the stirring speed of the plating liquid during plating. . That is, at the beginning of the plating process, the stirring speed is increased to shorten the residence time of the self-lubricating agent, etc. on the liquid surface, and the density of the self-lubricating agent, etc. in the plating layer 6 is reduced.

By including the above-mentioned self-lubricating agent in the plating layer 6, as the plating layer 6 wears out, the self-lubricating agent is exposed to the sliding surface and performs a lubricating action, and the sliding surface and Suppresses cylinder bore wear. In addition, in the state shown in Fig. 1D, the sliding surface 2
In the prior art, when this state was reached, wear increased rapidly, but according to this embodiment, wear is significantly reduced due to the action of the self-lubricating agent.

Now, if a self-lubricating agent or the like is contained in the plating layer 6, it is the same as mixing foreign matter in the plating layer, and the plating strength usually decreases, but in this embodiment, the lower edge of the outer periphery of the ring member 4 Since the portion 7 supports the plating layer 6 from below, there is no such problem. That is, when the piston ring is lowered, the gas pressure acting on the upper surface of the plating layer 6 is received by the outer peripheral lower edge 7, and when the piston ring is rising, the gas pressure acting on the upper surface of the plating layer 6 is received by the downward pressure acting on the plating layer 6 through the cylinder bore. The sliding resistance is also supported by the lower outer peripheral edge 7.

Furthermore, since the composite plating layer formed in the notch 5 has a relatively large amount of self-lubricating agent concentrated on the sliding surface 2, wear of the sliding surface 2 and the cylinder bore can be suppressed at an early stage. I can do it. Furthermore, since almost no self-lubricating agent or the like exists at the boundary between the plating layer 6 and the ring member 4, the plating layer 6
The adhesion strength to the ring member 4 becomes stronger.

FIG. 3 shows a second embodiment of the present invention, and shows the first embodiment of the invention.
Ring member 4 with plating layer 6 than that of the example
In order to strengthen the adhesion strength to the ring member 4,
The upper wall portion 8 of the cutout portion 5 is slightly inclined downward. According to this second embodiment, the plating layer 6
can be supported from above, resulting in superior strength.

FIG. 4 shows a third embodiment of the present invention, in which a composite plating layer 6 is formed on the entire outer periphery of the ring member 4, and the sliding surface 2 is formed into a round shape so that there are no corners. . The sliding surface 2 is formed into a round shape by polishing.

Note that the present invention may be applied to any piston ring, and is not limited to a top ring.

As described above, according to the present invention, during use, as the plating layer formed on the outer periphery of the piston ring, that is, the upper part of the sliding surface, wears out, the self-lubricating agent or anti-wear agent is exposed on the sliding surface. It has a lubricating effect, and can significantly reduce wear on the upper part of the piston ring sliding surface, where wear is particularly severe.
Accordingly, the wear of the cylinder bore can also be reduced, which in turn can reduce blow-by gas and reduce the amount of engine oil consumed.

Further, according to the present invention, since a relatively large amount of self-lubricating agent or anti-wear agent is concentrated on the ring sliding surface, wear of the sliding surface and cylinder bore can be suppressed at an early stage. Since almost no lubricant or the like exists at the boundary between the plating layer and the ring member, the adhesion strength of the plating layer to the ring member becomes stronger.

[Brief explanation of drawings]

Figures 1A to D are explanatory diagrams showing the progress of wear on the sliding surface and cylinder bore of a conventional piston ring, Figure 2 is a cross-sectional view of the main part showing the first embodiment of the present invention, and Figure 3 is A sectional view of main parts showing a second embodiment,
FIG. 4 is a sectional view of main parts showing the third embodiment. DESCRIPTION OF SYMBOLS 1...Piston ring, 2...Sliding surface, 4...Ring member, 6...Composite plating layer.

Claims (1)

[Claims for Utility Model Registration] 1. A composite plating layer containing a self-lubricating agent or anti-wear agent is formed on at least the upper part of the outer periphery of the ring member, and the self-lubricating agent or anti-wear agent in the composite plating layer is A piston ring characterized by a relatively high density on the sliding surface side. 2. The piston ring according to claim 1, wherein the self-lubricating agent or anti-wear agent is contained in the composite plating layer in the form of microcapsules wrapped in a polymer film.