Bearings – Rotary bearing – Fluid bearing
Reexamination Certificate
1999-06-24
2001-01-23
Luong, Vinh T. (Department: 3682)
Bearings
Rotary bearing
Fluid bearing
C384S292000, C384S912000
Reexamination Certificate
active
06176619
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Art
The present invention relates to a water lubricated bearing or water lubricated seal which has high wear resistance and a low coefficient of friction, and more particularly to a water lubricated bearing or water lubricated seal which is suitable for use in fluid machinery, e.g., pumps, turbines, compressors, etc.
2. Prior Art
Many conventional water lubricated bearings or water lubricated seals which have heretofore been used for fluid machinery, e.g., pumps, turbines, compressors, etc., have an arrangement comprising a combination of a movable member which employs a ceramic material such as SiC as a substrate, and a stationary member which employs a hard metal such as tungsten carbide (WC) as a substrate.
With the need for fluid machinery to be reduced in size, operate at higher speed and increase in capacity, service conditions under which seals and bearings are used have become increasingly adverse in recent years. That is, seals and bearings are now used under high-speed and heavy-load conditions. Accordingly, it has been pointed out that a material such as a hard metal which has heretofore been used for seals and bearings gives rise to problems such as fracturing under thermal shock and thermal fatigue cracking, caused by repeated application of friction heat generated by sliding contact between solids.
On the other hand, ceramic materials, e.g., SiC, are superior to hard metals in resistance to thermal stress caused by sliding. However, when used as a material for a high-speed rotating member, a ceramic material is inferior in mechanical strength and lacks resistance to shock. Further, when a metallic material is used as a sliding member, the surface of the metallic material may be subjected to carburizing, nitrating or other similar hardening treatment. With these surface treatments, however, a satisfactory sliding surface cannot be obtained in terms of the hardness of the modified layer itself and the deformation of the substrate after the treatment.
In addition, in a conventional water lubricated bearing or water lubricated seal adopting a titanium nitride film coated on a substrate of a metallic material, since an appropriate material for mating with the titanium nitride film has not been provided, sufficient sliding characteristics in water could not been obtained.
SUMMARY OF THE INVENTION
In view of the above-described circumstances, an object of the present invention is to provide a water lubricated bearing or water lubricated seal which has a reduced coefficient of friction, and which provides improved wear resistance.
Another object of the present invention is to provide a water lubricated bearing or water lubricated seal which has excellent anti-heat shock and anti-mechanical shock properties.
To solve the above-described problems, according to a first aspect of the present invention, a water lubricated bearing or water lubricated seal using water as a lubricant comprises: a rotary member secured directly or indirectly to a rotary side, and a stationary member secured directly or indirectly to a stationary side and facing the rotary member for making sliding contact therewith; wherein a substrate of either one of the rotary member and the stationary member is a metallic material and a thin titanium nitride film is formed on sliding surface thereof, and wherein the other member is made of a non-brittle material or a film of hard material is formed on the sliding surface thereof.
The non-brittle material may be a metallic material, and the film of hard material may be a ceramic film.
The ceramic film may be a nitride ceramic film such as a chromium nitride film, a boron nitride film, a titanium nitride film, or a film made of a material consisting essentially of an iron nitride, an oxide ceramic film such as a film made of a material consisting essentially of a chromium oxide, an aluminium oxide, a titanium oxide, a zirconium oxide, or a composite oxide of an aluminium oxide and a chromium oxide, or a carbide ceramic film such as a diamond-like carbon film, or a film made of a material consisting essentially of a tungsten carbide or a chromium carbide.
In a water lubricated bearing or water lubricated seal described above, the ceramic film may be formed by chemical vapor deposition, physical vapor deposition, spraying, wet plating or hot dipping.
The physical vapor deposition may be effected by a film forming method using an ion beam such as sputtering, ion plating, ion implantation, a joint method of ion implantation and vacuum evaporation, or the like.
According to a second aspect of the present invention, in a water lubricated bearing or water lubricated seal according to the first aspect, the non-brittle material is a metallic material, and the film of hard material is a hard chromium plating formed on the sliding surface of the other member.
According to a third aspect of the present invention, in a water lubricated bearing or water lubricated seal according to the first aspect: at least the sliding surface of the other member is made of a martensitic stainless steel.
According to a fourth aspect of the present invention, in a water lubricated bearing or water lubricated seal according to the first aspect: at least the sliding surface of the other member is made of a polyether ether ketone including a carbon fiber or a polytetrafluoroethylen resin including a carbon fiber.
According to a fifth aspect of the present invention, a water lubricated bearing or water lubricated seal using water as a lubricant comprises: a rotary member secured directly or indirectly to a rotary side, and a stationary member secured directly or indirectly to a stationary side and facing the rotary member for making sliding contact therewith; wherein a substrate of either one of the rotary member and the stationary member is a metallic material and a thin titanium nitride film is formed on the sliding surface thereof, wherein at least the sliding surface of the other member is made of a hard carbon.
According to the arrangement of the present invention described above, since the substrate of the rotary member and the stationary member or the rotary member and the stationary member themselves are made of a non-brittle material, they can provide excellent anti-heat shock and anti-mechanical shock properties. In addition, since the sliding surface of the rotary member and or the stationary member is formed with a film of hard material, it can provide a low coefficient of friction and improved wear resistance.
The above and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which preferred embodiments of the present invention are shown by way of illustrative examples.
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Kakutani Momoko
Kimura Yoshikazu
Nagasaka Hiroshi
Sugiyama Kenichi
Armstrong, Westerman Hattori, McLeland & Naughton
Ebara Corporation
Kaness Matthew A.
Luong Vinh T.
LandOfFree
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