DE3506746A1 - PISTON RING - Google Patents

Description

Piston ring

description

The invention relates to a piston ring for an internal combustion engine, in particular to a piston ring for the use in an internal combustion engine that works with heavily leaded or highly corrosive fuel Is exposed to influences.

In view of the problem of environmental pollution, the use of unleaded fuel is currently being used promoted and promoted, nonetheless, however

internal combustion engines still operated everywhere, which with 15

heavily leaded fuel work. To in such an internal combustion engine working with heavily leaded fuel To prevent excessive wear of the piston rings, the outer peripheral surface of the piston rings provided with a thick chrome plating, which is strongly corrosive, e.g. attack by HCl, able to withstand.

So far, however, no satisfactory benefit has been achieved with regard to productivity and costs.

In this context, piston rings have also been developed whose sliding surfaces are hardened by nitriding are. Under unfavorable operating conditions of the internal combustion engine, however, a piston ring can develop excessive wear and tear, especially rough wear, occur. Applicants' US Pat. No. 4,407,515 describes a combined oil ring, the expansion area and supporting webs of which have been subjected to a soft nitriding treatment.

Furthermore, US patent application 571 630 of An-35 describes

detectorin a piston ring with a ring body made of cast iron or steel, which over its entire surface with a soft nitrided layer and on its outer

The circumferential surface is provided with a sprayed or sprayed layer.

An object of the invention is to provide a piston ring in which the above deficiencies are more known Piston rings are eliminated.

According to the invention, a piston ring has an annular body made of steel or cast iron. On the entire surface of the A nitrided layer is formed in the ring body. The nitrided layer is composed of a diffusion layer and an overlying composite layer. At least the composite layer is removed from the outer circumferential surface of the ring body. On the exposed A plated or sprayed-on layer is applied to the diffusion layer or surface of the ring body.

The invention also provides a method for producing a piston ring of the type mentioned, in which the entire surface of an annular body made of steel or cast iron is provided with a nitrided layer, which is composed of a diffusion layer and a composite layer. Then on the outer peripheral surface of the ring body removed at least the composite layer, whereupon the exposed surface of the Annular body or the diffusion layer is provided with a plated or sprayed-on layer.

In the following, exemplary embodiments of the invention are explained with reference to the drawing. Show it:

Fig. 1 is a sectional view of a piston ring in one embodiment of the invention and

Fig. 2 is a sectional view of a piston ring in another embodiment of the invention.

A piston ring shown in a first embodiment of the ^{charge in FIG. 1} has an annular body 20 made of cast iron or steel, shown in section, which is provided with a nitrided layer 2 on its entire surface. The nitrided layer 2 is composed of a diffusion layer 22 and a composite layer 21 above it. On the outer circumferential surface 11 of the ring body 20, the composite layer 21 is removed by grinding or the like in order to expose the diffusion layer 22, since between the composite layer and a layer plated or sprayed onto this would not be able to achieve a sufficiently strong cohesive connection. A plated or sprayed-on layer 3 is then produced on the diffusion layer 22 exposed in this way.

In the case of the second embodiment shown in a sectional view in FIG. 2, there is on the outer circumferential surface 11 of the ring body 20, the entire nitrided layer 2 including the diffusion and the composite layer removed, and a plated or sprayed layer 3 is on the exposed outer peripheral surface of the ring body 20 trained.

The plated layer may be made from such as chromium or from a dispersion of discrete particles in one with the material of the cylinder or the cylinder liner compatible plating matrix be formed while the sprayed layer can be formed from an iron material or molybdenum.

As described above, in one embodiment of the invention, after removing a composite layer on the outer peripheral surface of a piston ring a plated or sprayed layer on a diffusion layer formed, whereby one caused by the friction between the composite layer and a cylinder wall excessive wear and tear, especially rough wear, is prevented.

BAD ORIO ^ JAL

In another embodiment, not only the composite layer, but also removed the diffusion layer on the outer peripheral surface of the piston ring, whereupon a plated or sprayed-on layer is formed on the thereby exposed base metal of the piston ring body will. This considerably improves the wear resistance of the sliding surface of the piston ring compared to a piston ring having a thin hard layer formed on a diffusion layer on the cylinder wall slides.

In both embodiments, the nitrided layers present on the side surfaces of the piston ring prevent excessive wear from repeated impacts on the walls of the piston groove. It also increased the wear resistance of the sliding surface is achieved through the combination of a nitrided layer with a Plating or sprayed-on layer brought about a synergetic effect.

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Claims (9)

Patent claims: ^, Piston ring, characterized in that an annular body (20) formed from steel or cast iron over its entire surfaces with a nitrided one Layer (2) is provided, which consists of a diffusion layer and a composite layer (22 or 21) composed that on the outer peripheral surface (11) of the ring body at least the composite layer is removed and that on the outer peripheral surface of the ring body a plated or sprayed-on layer (3) is formed. 2. Piston ring according to claim 1, characterized in that on the outer peripheral surface (11) of the ring body (20) only the diffusion layer (22) is present and that the plated or sprayed-on layer (3) is formed on the diffusion layer. 3. Piston ring according to claim 1, characterized in that g e k e η η, that the plated or sprayed-on layer (3) directly on the outer peripheral surface (11) of the ring body (20) is formed. 4. Piston ring according to claim 1, characterized in that g e k e η η, that the plated layer (3) is formed from chromium. 5. Piston ring according to claim 1, characterized in that the plated layer (3) consists of a Dispersion of discrete particles is formed in a plating matrix. 6. Piston ring according to claim 1, characterized in that g e k e η η, that the sprayed-on layer (3) is formed from an iron material. 7. Piston ring according to claim 1, characterized in that the sprayed-on layer (3) consists of Molybdenum is formed. 8. A method for producing a piston ring, characterized in that on the entire surfaces a ring body made of steel or cast iron a riveted layer is formed, which consists of a Diffusionschxcht and an overlying composite layer composed that on the outer peripheral surface of the ring body at least the composite layer of the nitrided layer is removed and that on the exposed outer peripheral surface of the ring body a plated or sprayed layer is formed. 9. The method according to claim 8, characterized in that both the composite and the 1 diffusion layer of the nitrided layer on the outer circumferential surface of the ring body can be removed.