Seal for a joint or juncture – Seal between relatively movable parts – Piston ring or piston ring expander or seat therefor
Reexamination Certificate
1999-01-29
2001-08-07
Mah, Chuck Y. (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Piston ring or piston ring expander or seat therefor
C277S443000, C277S444000, C277S447000
Reexamination Certificate
active
06270081
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a combination of piston rings for use in an internal combustion engine, and more particularly, to the combination including at least one compression ring and at least one oil ring.
In accordance with recent requirement in higher engine performance, various machine components of the internal combustion engine are subjected to severe working conditions, and the engine must provide a prolonged durability. Piston rings are operated under higher engine rotation, higher temperature, and higher planner pressure than before, and enhancement of durability is highly required. Further, in accordance with a demand in improvement on engine performance and reduction in engine size, various combination of compression rings and oil rings are provided in an gasoline engine and Diesel engine, such as a combination of three compression rings and two oil rings, a combination of three compression rings and a single oil ring, a combination of a two compression rings and a single oil ring and a combination of a single compression ring and a single oil ring.
In order to improve durability of the piston rings, wear resistant treatment is effected on sliding surfaces of the piston rings such as a high hardness chromium plating and nitriding treatment. However, wear resistance in a conventional piston ring having the chromium plating is still insufficient. On the other hand, the nitriding treatment provides excellent wear resistance, and therefore, the nitriding treatment is becoming popular and is used for a first compression ring or a top ring which suffers from severe working condition since the top ring is positioned closest to a combustion chamber among the piston rings installed on a piston. Still however, the conventional piston ring provided with the nitriding treatment is still insufficient in wear resistance, scuffing resistance, and anti-attacking performance against an opposing component in relative sliding relation to the piston ring.
In order to overcome the above-described problems, laid open Japanese Patent Application Kokai Hei 7-239032 discloses a combination of a plurality of compression rings and at least one oil ring for use in an internal combustion engine. In the combination, an ion plating layer is formed on an outer peripheral sliding surface of a first compression ring and the at least one oil ring. By the formation of the ion plating layer, wear resistance, scuffing resistance, anti-attacking performance against an opposing component and corrosion resistance are improved in comparison with the conventional piston ring combination provided with the nitriding layer. Here, individual development of the surface layer for the compression ring and the oil ring is required in an attempt to further improve wear resistance, scuffing resistance, anti-attacking performance against the opposing component, and corrosion resistance.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a combination of piston rings for use in an internal combustion engine, the combination being capable of further improving wear resistance, and scuffing resistance, and reducing attacking performance against an opposing component as much as possible.
This and other objects of the present invention will be attained by a combination of a piston rings for use in an internal combustion engine, the piston rings including at least one compression ring including a top ring having an outer peripheral surface formed with a first ion plating layer, and at least one oil ring having an outer peripheral surface formed with a second ion plating layer, the combination comprising the improved first ion plating layer and the second ion plating layer. The first ion plating layer is formed of a mixture of Cr—N and has a porous structure with a porosity ranging from 3 to 10%. The second ion plating layer is formed of a mixture of Cr—N and has a dense structure with a porosity ranging from 0 to 3%.
Preferably, the first ion plating layer has a hardness ranging from 1000 to 1500 Hv, and the second ion playing layer has a hardness ranging from 1800 to 2200 Hv.
In another aspect of the invention, there is provided a combination of a piston rings for use in an internal combustion engine, the piston rings including at least one compression ring including a top ring having an outer peripheral surface formed with a first ion plating layer, and at least one oil ring having an outer peripheral surface formed with a second ion plating layer, the combination comprising the improved first and second ion plating layers. The first ion plating layer is formed of a mixture of Cr—N and has a hardness ranging from 1000 to 1500 Hv. The second ion plating layer is formed of a mixture of Cr—N and has a hardness ranging from 1800 to 2200 Hv.
With this arrangement, the outer sliding layer of the top ring, which undergoes the severest working condition among the piston rings, can provide sufficient wear resistance, scuffing resistance, and a moderate attacking nature against opponent member. Further, cracking of the layer or separation of the layer from the base body of the top ring can be prevented because of the sufficient resiliently restoring force of the layer. Further, the outer sliding layer of at least one oil ring can provide sufficient wear resistance and sufficient oil scraping function. Thus, with the combination of the first and second ion plating layers, enhanced engine performance can result.
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Onoda Motonobu
Sakai Takao
Mah Chuck Y.
Nippon Piston Ring Co. Ltd.
Patel Vishal
Sughrue Mion Zinn Macpeak & Seas, PLLC
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