Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic nitrogen compound
Patent
1997-02-20
1998-03-17
Willis, Jr., Prince
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic nitrogen compound
508581, C10M11508
Patent
active
057286590
DESCRIPTION:
BRIEF SUMMARY
FIELD OF ART
The present invention relates to a grease composition for rolling bearings. More particularly, it relates to a grease composition employed for rolling bearings in electrical components and accessory devices for automotive vehicles, such as alternators, electromagnetic clutches for car air conditioners, idle pulleys, electric fan motors, or the like.
BACKGROUND OF THE INVENTION
In automotive vehicles, for keeping up with the propagation FF (front engine-front wheel driven) cars aiming at reducing size and weight of the vehicles, and with the demand for an increased cabin space within the cars, the engine room space has necessarily been reduced, so that the size and weight of the electrical components and accessories such as alternators, electromagnetic clutches for car air conditioners, idle pulleys, or electric fan motors have further been reduced. On the other hand, higher performance and higher output power are demanded of the electrical components and accessories. Therefore, for example, reduction in output power caused by size reduction of an alternator is compensated by increasing the designed speed. Further, to keep up with the demand for quiet operation, the degree of hermetic sealing of the engine room is advanced and hence the engine room tends to be heated, so that components capable of withstanding higher temperatures are required. In these electrical components and accessories, rolling bearings are used, and lubrication of the rolling bearings is achieved mainly by using a grease. Currently, the greases for use in sealed bearings employed in electrical components and accessories for automotive vehicles are required to achieve longer flaking life and bearing lubricating life, less grease leakage, superior low-temperature properties, superior rust-preventive properties, and superior noiseless operation of the bearings.
Japanese Laid-open Patent Application Nos. 5-98280, 5-194979, and 5-263091 disclose greases containing as a thickener a diurea compound having aromatics containing-hydrocarbon groups at most of its terminals. These greases have prolonged flaking life on the bearings, but have inferior fluidity, so that they cause burning of the bearings under high temperature and high speed operative conditions, leaving problems in bearing lubrication life.
Japanese Laid-open Patent Application Nos. 3-79698, 5-140576, and 6-17079 disclose greases containing as a thickener a diurea compound having cyclohexyl groups at most of its terminals. These greases have prolonged bearing lubrication life under high temperature and high speed operative conditions, but do not have sufficient flaking life.
Japanese Laid-open Patent Application No. 4-253796 discloses a grease containing as a thickener a diurea compound having both a cyclohexyl group and an alkyl group at its terminals. Japanese Laid-open Patent Application No. 6-88085 discloses a grease containing as a thickener a diurea compound having an aromatics-containing hydrocarbon group, a cyclohexyl group, and an alkyl group at its terminals. These greases have inferior flaking life and shear stability, and cause high degree of grease leakage.
Japanese Laid-open Patent Application No. 61-155496 discloses a grease containing as a thickener a diurea compound having a long chained alkylphenyl group and a cyclohexyl group at its terminals. This grease exhibits enough durability under a certain degree of high temperature and high speed operative conditions, but does not exhibit enough durability under severe conditions such as dmn value of not less than 600,000 and the temperature of not lower than 150.degree. C.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a grease composition for a rolling bearing having a greatly prolonged bearing lubricating life and flaking life particularly under high temperature and high speed operative conditions of the bearings.
According to the present invention, there is provided a grease composition for a rolling bearing comprising 10 to 60 parts by weight of a mixture of diure
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Iso Kenichi
Itano Fumihiro
Kinoshita Hirotugu
Koizumi Hideki
Naka Michiharu
Nippon Oil Co. Ltd.
NSK Ltd.
Toomer Cephia D.
Willis Jr. Prince
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