# US 8,771,086 B2 · Fixed-type constant velocity universal joint > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,771,086 B2 - Document ID: US8771086B2 - Status: Granted - Kind: B2 - Application number: 13/808,731 - Filed: 2011-07-19 - Published: 2013-05-02 - Granted: 2014-07-08 - Earliest claimed: 2010-08-05 - Assignees: Ntn Corporation - Applicants: Kazuhiko Yoshida; Keisuke Sone; Mika Kohara - Inventors: Kazuhiko Yoshida; Keisuke Sone; Mika Kohara - Web page: https://patentgrep.com/patent/US8771086B2 ## CPC - F16C 1/04: Articulated shafts - C10M 141/10: at least one of them being an organic phosphorus-containing compound - C10M 169/06: Mixtures of thickeners and additives - F16D 3/223: the rolling members being guided in grooves in both coupling parts - F16D 3/2237: where the grooves are composed of radii and adjoining straight lines, i.e. undercut free [UF] type joints - F16D 3/2245: where the groove centres are offset from the joint centre - C10M 2201/066: Molybdenum sulfide - C10M 2203/1006: used as base material - C10M 2207/401: used as base material - C10M 2215/1026: used as thickening material - C10M 2215/221: Six-membered rings containing nitrogen and carbon only - C10M 2219/044: Sulfonic acids, Derivatives thereof, e.g. neutral salts - C10M 2219/046: Overbased sulfonic acid salts - C10M 2219/068: Thiocarbamate metal salts - C10M 2223/045: Metal containing thio derivatives - C10N 2030/06: Oiliness; Film-strength; Anti-wear; Resistance to extreme pressure - C10N 2040/046: {for traction drives} - C10N 2050/10: semi-solid; greasy - F16D 2003/22309: {Details of grooves} - F16D 2003/22316: {Means for fastening or attaching the bellows or gaiters} - F16D 2300/06: Lubrication details not provided for in group F16D13/74 - F16D 2300/10: Surface characteristics; Details related to material surfaces - F16D 2300/12: Mounting or assembling - F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS - C10M: LUBRICATING COMPOSITIONS (well drilling compositions C09K8/02); USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION (mould release, i.e. separating, agents for metals B22C3/00, for plastics or substances in a plastic state, in general B29C33/56, for glass C03B40/02; textile lubricating compositions D06M11/00, D06M13/00, D06M15/00; immersion oils for microscopy G02B21/33) - F16D: COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES - C10N: INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS ## Abstract A fixed type constant velocity universal joint comprises a ball and a lubricating grease sealed therein. A surface roughness of the ball is set to Ra 0.15 μm or less and a surface roughness of a counterpart surface on which the ball rolls is set to be higher than the surface roughness of the ball. An additive composition of the lubricating grease comprises a base oil, a diurea compound, molybdenum dithiocarbamate, zinc dialkyldithiophosphate, melamine cyanurate, molybdenum disulfide, and calcium salt of alkylaromatic sulfonic acid. ## Claims ### Claim 1 A fixed constant velocity universal joint, comprising: an outer joint member having an inner surface provided with track grooves; an inner joint member having an outer surface provided with track grooves paired with the track grooves of the outer joint member; a plurality of balls for transmitting torque, the plurality of balls being interposed between the track grooves of the outer joint member and the track grooves of the inner joint member; and a cage for holding the plurality of balls, the cage being interposed between the inner surface of the outer joint member and the outer surface of the inner joint member, the fixed constant velocity universal joint comprising a lubricating grease sealed therein, wherein the plurality of balls comprises eight balls, wherein a spherical angle of the outer joint member is within a range from 17° to 18.5°, wherein the outer joint member comprises a spherical inlet provided with cut out portions for incorporation of the cage, wherein a surface roughness of each of the plurality of balls is Ra 0.15 μm or less, wherein a surface roughness of a counterpart surface on which a corresponding one of the plurality of balls rolls is within a range from Ra 0.4 μm to Ra 1.8 μm so as to be higher than the surface roughness of each of the plurality of balls, and wherein an additive composition of the lubricating grease comprises a base oil, a diurea compound, molybdenum dithiocarbamate, zinc dialkyldithiophosphate, melamine cyanurate, molybdenum disulfide, and calcium salt of alkylaromatic sulfonic acid. ### Claim 2 (depends on 1) A fixed constant velocity universal joint according to claim 1, wherein the additive composition of the lubricating grease comprises the melamine cyanurate at 2 to 4% by weight, the molybdenum disulfide at 0.2 to 2.5% by weight, the molybdenum dithiocarbamate at 1 to 3% by weight, the zinc dialkyldithiophosphate at 0.2 to 1.5% by weight, and the calcium salt of the alkylaromatic sulfonic acid at 0.5 to 3.5% by weight. ### Claim 3 (depends on 2) A fixed constant velocity universal joint according to claim 2, wherein the additive composition of the lubricating grease further comprises a vegetable oil. ### Claim 4 (depends on 3) A fixed constant velocity universal joint according to claim 3, wherein the fixed constant velocity universal joint comprises an undercut free fixed constant velocity universal joint in which a bottom surface of each of the track grooves of the outer joint member and a bottom surface of each of the track grooves of the inner joint member each comprise a curved portion and a straight portion. ### Claim 5 (depends on 2) A fixed constant velocity universal joint according to claim 2, wherein the base oil of the additive composition comprises a mineral oil. ### Claim 6 (depends on 5) A fixed constant velocity universal joint according to claim 5, wherein the fixed constant velocity universal joint comprises an undercut free fixed constant velocity universal joint in which a bottom surface of each of the track grooves of the outer joint member and a bottom surface of each of the track grooves of the inner joint member each comprise a curved portion and a straight portion. ### Claim 7 (depends on 2) A fixed constant velocity universal joint according to claim 2, wherein the fixed constant velocity universal joint comprises an undercut free fixed constant velocity universal joint in which a bottom surface of each of the track grooves of the outer joint member and a bottom surface of each of the track grooves of the inner joint member each comprise a curved portion and a straight portion. ### Claim 8 (depends on 1) A fixed constant velocity universal joint according to claim 1, wherein the additive composition of the lubricating grease further comprises a vegetable oil. ### Claim 9 (depends on 8) A fixed constant velocity universal joint according to claim 8, wherein the base oil of the additive composition comprises a mineral oil. ### Claim 10 (depends on 9) A fixed constant velocity universal joint according to claim 9, wherein a center of curvature of each of the track grooves of the outer joint member and a center of curvature of a corresponding one of the track grooves of the inner joint member are offset to each other with respect to a joint axial center line to the opposite sides in a radial direction by equal distances with respect respectively to a corresponding one of the track grooves of the outer joint member and a corresponding one of the track grooves of the inner joint member. ### Claim 11 (depends on 8) A fixed constant velocity universal joint according to claim 8, wherein the fixed constant velocity universal joint comprises an undercut free fixed constant velocity universal joint in which a bottom surface of each of the track grooves of the outer joint member and a bottom surface of each of the track grooves of the inner joint member each comprise a curved portion and a straight portion. ### Claim 12 (depends on 1) A fixed constant velocity universal joint according to claim 1, wherein the base oil of the additive composition comprises a mineral oil. ### Claim 13 (depends on 12) A fixed constant velocity universal joint according to claim 12, wherein the fixed constant velocity universal joint comprises an undercut free fixed constant velocity universal joint in which a bottom surface of each of the track grooves of the outer joint member and a bottom surface of each of the track grooves of the inner joint member each comprise a curved portion and a straight portion. ### Claim 14 (depends on 1) A fixed constant velocity universal joint according to claim 1, wherein the fixed constant velocity universal joint comprises an undercut free fixed constant velocity universal joint in which a bottom surface of each of the track grooves of the outer joint member and a bottom surface of each of the track grooves of the inner joint member each comprise a curved portion and a straight portion. ### Claim 15 (depends on 14) A fixed constant velocity universal joint according to claim 14, wherein a center of curvature of each of the track grooves of the outer joint member and a center of curvature of a corresponding one of the track grooves of the inner joint member are offset to each other with respect to a joint axial center line to opposite sides in a radial direction by equal distances with respect a corresponding one of the track grooves of the outer joint member and a corresponding one of the track grooves of the inner joint member. ### Claim 16 (depends on 15) A fixed constant velocity universal joint according to claim 15, wherein a raw material for the cage comprises carbon steel having a carbon content of 0.46% by weight or more and 0.50% by weight or less, the raw material having a core portion which has a hardness in a range from HRC 56 to HRC 60 after quenching.