# US 8,784,253 B2 · Transmission ratio variable device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,784,253 B2 - Document ID: US8784253B2 - Status: Granted - Kind: B2 - Application number: 13/955,602 - Filed: 2013-07-31 - Published: 2014-02-13 - Granted: 2014-07-22 - Earliest claimed: 2012-08-08 - Assignees: Jtekt Corporation - Applicants: JTEKT Corporation - Inventors: Hitoshi Sasaki; Satoshi Motoyama; Tomonari Yamakawa; Masanori Natsume - Web page: https://patentgrep.com/patent/US8784253B2 ## CPC - F16H 3/70: in which the central axis of the gearing lies inside the periphery of an orbital gear - B62D 5/008: {Changing the transfer ratio between the steering wheel and the steering gear by variable supply of energy, e.g. by using a superposition gear} - F16H 1/321: {the orbital gear being nutating} - F16H: GEARING - B62D: MOTOR VEHICLES; TRAILERS (steering, or guiding on a desired track, of agricultural machines or implements A01B69/00; wheels, castors, axles, increasing wheel adhesion B60B; vehicle tyres, tyre inflation or tyre changing B60C; connections between vehicles of a train or the like B60D; vehicles for use on rail and road, amphibious or convertible vehicles B60F; suspension arrangements B60G; heating, cooling, ventilating or other air treating devices B60H; windows, windscreens, non-fixed roofs, doors or similar devices, protective coverings for vehicles not in use B60J; propulsion plant arrangements, auxiliary drives, transmissions, controls, instrumentation or dashboards B60K; electric equipment or propulsion of electrically-propelled vehicles B60L; power supply for electrically-propelled vehicles B60M; passenger accommodation not otherwise provided for B60N; adaptations for load transportation or to carry special loads or objects B60P; arrangement of signalling or lighting devices, the mounting or supporting thereof or circuits therefor, for vehicles in general B60Q; vehicles, vehicle fittings or vehicle parts not otherwise provided for B60R; servicing, cleaning, repairing, supporting, lifting, or manoeuvring, not otherwise provided for, B60S; brake arrangements, brake control systems or parts thereof B60T; air-cushion vehicles B60V; motor-cycles, accessories therefor B62J, B62K; testing of vehicles G01M) ## Abstract A second shaft is configured by a shaft portion extending outside a housing in which a nutation gear mechanism is housed, a housing portion, and a cylindrical portion. A communicating hole, through which an outside and an inside of the housing portion communicate with each other, is formed in the shaft portion. A preload applying mechanism includes a preload adjusting plug that is screwed to the housing portion and is able to be operated from outside through the communicating hole, a wave washer compressed in accordance with a position of the preload adjusting plug, and a lock nut that is screwed to the housing portion of the second shaft so as to press the preload adjusting plug toward the nutation gear mechanism. ## Claims ### Claim 1 A transmission ratio variable device that adds motor-driven rotation to rotation of an input shaft by using a differential mechanism, and transmits resultant rotation to an output shaft, characterized in that: a nutation gear mechanism is employed as the differential mechanism, and the nutation gear mechanism includes a first gear that rotates together with the input shaft, a fourth gear that rotates together with the output shaft, and a nutation gear that includes a second gear that meshes with the first gear and a third gear that meshes with the fourth gear, the nutation gear rotating about an axis that is inclined to an axis of the first and fourth gears; one of the input shaft and the output shaft has a shaft portion projecting outside a housing that houses the nutation gear mechanism, and a communicating hole, through which an outside and an inside of the housing communicate with each other, is formed in the shaft portion; and the transmission ratio variable device includes preload applying means including a preload adjusting plug that is screwed to one of the input shaft and the output shaft and is able to be operated from outside through the communicating hole, the preload applying means applying an axial preload to the nutation gear mechanism in accordance with a position of the preload adjusting plug. ### Claim 2 (depends on 1) The transmission ratio variable device according to claim 1, wherein the preload applying means includes an elastic member that is arranged between the preload adjusting plug and the nutation gear mechanism and applies the axial preload to the nutation gear mechanism by being elastically deformed. ### Claim 3 (depends on 1) The transmission ratio variable device according to claim 1, comprising locking means that is able to restrict loosening of the preload adjusting plug. ### Claim 4 (depends on 3) The transmission ratio variable device according to claim 3, wherein a projecting portion, which is inserted in the communicating hole, is formed in the preload adjusting plug, and the locking means includes a swaged portion formed by swaging the shaft portion so that a diameter of the shaft portion is reduced. ### Claim 5 (depends on 3) The transmission ratio variable device according to claim 3, wherein the locking means includes a lock nut that is screwed to one of the input shaft and the output shaft so as to press the preload adjusting plug toward the nutation gear mechanism. ### Claim 6 (depends on 3) The transmission ratio variable device according to claim 3, wherein a press-fitting hole is formed in the preload adjusting plug, and the locking means includes a press-fitting member that is press-fitted into the press-fitting hole so as to deform the preload adjusting plug so that a diameter of the preload adjusting plug is increased. ### Claim 7 (depends on 6) The transmission ratio variable device according to claim 6, wherein the preload adjusting plug is provided with a low-strength portion in which mechanical strength is reduced. ### Claim 8 (depends on 6) The transmission ratio variable device according to claim 6, wherein the locking means includes a soft member that is provided in a screwed portion between one of the input shaft and the output shaft, and the preload adjusting plug, and the soft member has lower mechanical strength than mechanical strength of the preload adjusting plug. ### Claim 9 (depends on 3) The transmission ratio variable device according to claim 3, wherein the locking means includes a friction plate that is restricted from rotating relative to one of the input shaft and the output shaft by engagement between a projection and a recess, the friction plate contacting the preload adjusting plug. ### Claim 10 (depends on 9) The transmission ratio variable device according to claim 9, wherein at least one of contact surfaces between the preload adjusting plug and the friction plate has been subjected to a high μ process for increasing a friction coefficient of the at least one contact surface.