Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Ptfe
Reexamination Certificate
1999-09-28
2001-12-11
McAvoy, Ellen M. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Ptfe
C508S582000, C384S462000, C384S463000
Reexamination Certificate
active
06329326
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rolling bearing for use in automobile fuel jet controller, particularly apparatus for controlling the speed or idle rotation, exhaust gas recycling apparatus, electronic throttle controller, etc. More particularly, the present invention relates to a rolling bearing for fuel jet controller having improved low temperature torque properties and high temperature durability.
2. Description of the Related Art
Rolling bearings for use in automobile fuel jet controller such as apparatus for controlling the speed of idle rotation, exhaust gas recycling apparatus and electronic throttle controller are often required to exhibit a good durability at high temperatures and good torque properties at low temperatures. To this end, high temperature durability or low temperature torque properties have been heretofore attained by filling a lithium soap-ester oil-based grease or urea-synthetic hydrocarbon oil-based grease in the rolling bearing as a lubricant which uses a synthetic oil as a base oil. Low temperature torque properties, if particularly demanded, have been attained by the use of a lubricant such as ester oil and fluorine-based oil.
In recent years, however, the requirements for the performance of rolling bearings for use in these fuel jet controllers have been severer. For example, an exhaust gas recycling apparatus is intended to recycle exhaust gas which has been just emitted to further reduce the amount of NOx in the engine exhaust gas. Thus, the rolling bearing used in the exhaust gas recycling apparatus is exposed to temperatures as high as close to 200° C. Accordingly, lubricants which have heretofore been filled in these apparatus such as lithium soap-ester oil-based grease, urea-synthetic hydrocarbon-based grease, ester oil and fluorine-based oil cannot maintain high temperature durability.
As mentioned above, the grease or lubricant filled in the conventional rolling bearings for use in automobile fuel jet controller, particularly apparatus for controlling the speed or idle rotation, exhaust gas recycling apparatus, electronic throttle controller, etc. exhibits a limited high temperature durability while satisfying its desired low temperature torque properties. Thus, the conventional grease or lubricant cannot exhibit further improvement in high temperature durability. Further improvement has been desired in low temperature torque properties.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a rolling bearing having better low temperature torque properties and high temperature durability than ever particularly suitable for automobile fuel jet controller.
The present invention has been worked out as a result of extensive studies of solution to the foregoing problems. In order to satisfy the requirements for torque properties and durability between low temperature (about −40° C.) and high temperature (about 200° C.), the present invention provides a rolling bearing comprising a grease filled therein, said grease comprising a perfluoropolyether oil having a straight-chain structure having a dynamic viscosity of from 40 to 160 mm
2
/s at 40° C. as a base oil and a particulate fluororesin as a thickening agent.
In the foregoing description, the perfluoropolyether oil having a straight-chain structure which acts as a base oil exhibits a better heat resistance than that having a branched structure and thus exhibits a sufficient heat resistance at temperatures as high as higher than 200° C. The perfluoropolyether oil exhibits a high viscosity index and thus is little subject to thermal change in viscosity. Further, since the perfluoropolyether oil exhibits a dynamic viscosity of from 40 to 160 mm
2
/s at 40° C., it can contribute to improvement in torque properties at low temperatures. The particulate fluororesin which acts as a thickening agent, too, exhibits a good heat resistance.
Accordingly, the filling of the foregoing specific grease makes it possible for rolling bearing to maintain good bearing properties between low temperature and high temperature over an extended period of time.
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Hirayama Yasuhiro
Iso Kenichi
Koizumi Hideki
Okuma Kenji
Yokouchi Atsushi
McAvoy Ellen M.
NSK Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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