Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Inorganic compound
Reexamination Certificate
2000-06-29
2001-11-20
McAvoy, Ellen M. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Inorganic compound
C508S364000, C508S365000, C508S433000, C508S438000, C508S551000, C508S552000
Reexamination Certificate
active
06319880
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a grease composition for constant velocity joints of motorcars, in particular, a sliding type constant velocity joints. More specifically, the present invention pertains to a grease composition for constant velocity joints, which can efficiently lubricate the portions of a constant velocity joint which are easily worn out and are liable to generate abnormal vibrations or the like; can effectively reduce the wear; can suppress any vibration; and can improve the useful life of the joint.
Recently, FF cars have rapidly increased, from the viewpoint of, for instance, reduction of the weight and the insurance of the accommodation space of a car, functional 4WD cars have likewise increased and accordingly, there have widely been used constant velocity joints (CVJ) suitable for these applications. An embodiment of a double offset joint (DOJ) is shown in
FIG. 1
, which is used as a sliding type joint among these CVJ's. In this DOJ, when the joint transmits a running torque, while it has a working angle, the joint undergoes complicated rolling and sliding motions at the fitting position of track grooves
3
of an outside wheel
1
, track grooves
4
of an inside wheel
2
and balls
5
, and the frictional resistance in the sliding portions of the joint generates a force in the axial direction. This force is referred to as “an induced thrust force”. This DOJ is provided with track grooves
3
on the internal face of the outside wheel
1
at intervals of 60 degrees and therefore, the induced thrust force is generated 6 times per revolution.
If the cycle of such induced thrust forces is in agreement with the natural frequencies of, for instance, an engine, a car body and/or a suspension, a resonance of the car body is induced and this gives a disagreeable impression to the passengers of the car. Therefore, it is desirable to reduce the foregoing induced thrust force to a level as low as possible. In a packaged motorcar, inconvenience such as beating and stuffy sounds are generated during the high speed travelling of the motorcar due to the resonance. In addition, the lubricating conditions for the DOJs have increasingly become severer as the weight of the car has been reduced and the generating power of the engine has been increased, and correspondingly, the joint should be improved in the durability.
The conventional lithium-containing extreme-pressure grease, which comprises a sulfur-phosphorus-containing extreme-pressure additive, and a lithium-containing extreme-pressure grease composition, which comprises molybdenum disulfide, suffer from a problem concerning the vibration resistance. Moreover, these conventional extreme-pressure greases are greatly worn out under high contact pressure conditions and accordingly, they are also insufficient in the durability. Moreover, Japanese Un-Examined Patent Publication No. Sho 62-207397 discloses an extreme-pressure grease composition, which comprises, as an essential component, a sulfur-phosphorus-containing extreme-pressure additive comprising a combination of a molybdenum sulfurized dialkyl dithiocarbamate and at least one member selected from the group consisting of sulfurized fats and oils, sulfurized olefins, tricresyl phosphate, trialkyl phosphates and zinc dialkyl dithiophosphates. However, the extreme-pressure grease composition disclosed in this patent is still insufficient in the durability.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a grease composition for constant velocity joints, which is highly effective for reducing any induced thrust force and excellent in the durability.
It is another object of the present invention to provide a grease composition for constant velocity joints, which can efficiently lubricate such a constant velocity joint when it is applied to sites thereof to be lubricated, can efficiently inhibit any wear of the joint and is excellent in heat resistance and durability.
The inventors of this invention have conducted various intensive studies to achieve the foregoing objects, have found that the drawbacks associated with the conventional grease compositions for constant velocity joints can effectively be eliminated by the use of a specific combination of compounds and thus have completed the present invention.
More specifically, the foregoing object of the present invention can be accomplished by providing a grease composition for constant velocity joints, which comprises the following components:
(a) a base oil;
(b) a diurea type thickening agent;
(c) a molybdenum sulfurized dialkyl dithiocarbamate;
(d) molybdenum disulfide;
(e) at least one sulfur-phosphorus-containing extreme-pressure agent selected from the group consisting of zinc dithiophosphate compounds and thiophosphates; and
(f) a fatty acid amide.
The constant velocity joints, to which the grease composition according to the present invention is applied, are particularly preferably sliding type constant velocity joints.
REFERENCES:
patent: 3095375 (1963-06-01), Pitman
patent: 3223624 (1965-12-01), Morway et al.
patent: 3730895 (1973-05-01), Kjonaas
patent: 3840463 (1974-10-01), Froeschmann et al.
patent: 4062785 (1977-12-01), Nibert
patent: 4536308 (1985-08-01), Pehler et al.
patent: 4743389 (1988-05-01), Braid et al.
patent: 4759859 (1988-07-01), Waynick
patent: 4787992 (1988-11-01), Waynick
patent: 4830767 (1989-05-01), Waynick
patent: 4840740 (1989-06-01), Sato et al.
patent: 4902435 (1990-02-01), Waynick
patent: 5126062 (1992-06-01), Barnes
patent: 5160645 (1992-11-01), Okaniwa et al.
patent: 5207936 (1993-05-01), Anzai et al.
patent: 5589444 (1996-12-01), Hatakeyama
patent: 5607906 (1997-03-01), Okaniwa et al.
patent: 5952273 (1999-09-01), Suzuki et al.
patent: 6037314 (2000-03-01), Kondo et al.
patent: 0 508 115 (1992-10-01), None
patent: 0 558 099 (1993-09-01), None
patent: 0 811 675 (1997-12-01), None
patent: 2 761 372 (1998-10-01), None
patent: 62-207397 (1987-09-01), None
patent: 4-41714 (1992-07-01), None
patent: WO 94/11470 (1994-05-01), None
patent: WO 96/02615 (1996-02-01), None
Hasegawa Yukio
Imai Junichi
Okaniwa Takashi
Takabe Shinichi
Kyodo Yushi Co. Ltd.
McAvoy Ellen M.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
LandOfFree
Grease composition for constant velocity joint does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Grease composition for constant velocity joint, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Grease composition for constant velocity joint will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2596369