# US 2014/0190761 A1 · Steering system in a vehicle comprising an electric servomotor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0190761 A1 - Document ID: US20140190761A1 - Status: Published application - Kind: A1 - Application number: 14/049,481 - Filed: 2013-10-09 - Published: 2014-07-10 - Earliest claimed: 2013-01-10 - Assignees: ZF Lenksysteme GmbH - Applicants: Zf Lenksysteme GmbH - Inventors: Gerd REIMANN - Web page: https://patentgrep.com/patent/US20140190761A1 ## CPC - B62D 5/0409: {Electric motor acting on the steering column} - B62D 1/166: {Means changing the transfer ratio between steering wheel and steering 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} - B62D 5/0484: {for reaction to failures, e.g. limp home} - 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 steering system in a vehicle comprising an electric servomotor which includes a switching gearbox that is integrated into the steering shaft and has a switching actuator wherein a less direct gear ratio is presented when the switching actuator is de-energized than when it is energized. ## Claims ### Claim 1 A steering system in a vehicle comprising an electric servomotor for generating a servo torque supporting the steering motion, a switching gearbox comprising a switching actuator integrated in a steering shaft, wherein the gear ratio in the transmission path can be variably adjusted by way of the switching gearbox and has a less direct gear ratio when the switching actuator is de-energized than when it is energized. ### Claim 2 (depends on 1) The steering system according to claim 1, wherein the switching gearbox has a gear ratio of 1:1 in the energized state. ### Claim 3 (depends on 1) The steering system according to claim 1, wherein the switching gearbox has a gear ratio of at least 1:2, and preferably greater than or equal to 1:4, when de-energized. ### Claim 4 (depends on 1) A steering system according to claim 1, wherein a superimposing gearbox by way of which a superimposed steering angle (δM) can be superimposed on the steering angle (δL) specified by the driver is integrated into a steering shaft of the steering system. ### Claim 5 (depends on 4) The steering system according to claim 4, wherein the switching gearbox is disposed between the superimposing gearbox in the steering shaft and the steering gearbox. ### Claim 6 (depends on 4) The steering system according to claim 4, wherein the switching gearbox is integrated into the superimposing gearbox in the steering shaft. ### Claim 7 (depends on 4) A steering system according to claim 4, wherein the changed gear ratio of the de-energized switching gearbox can be compensated for by way of the superimposing gearbox, ### Claim 8 (depends on 1) A steering system according to claim 1, wherein the switching gearbox can be switched between exactly two gear ratios which are associated with the energized state and the de-energized state of the switching actuator. ### Claim 9 (depends on 1) A steering system according to claim 1, wherein the switching gearbox is designed as a planetary gear system. ### Claim 10 (depends on 1) A steering system according to claim 1, wherein the switching actuator comprises at least one electromagnetic actuator which fixes a gearbox component so as to be stationary in the housing or releases the same. ### Claim 11 (depends on 1) A steering system according to claim 1, wherein two switching actuators are provided, which fix the different gearbox components so as to be stationary in the housing, or release the same, and which are reciprocally open or closed when de-energized. ### Claim 12 (depends on 1) A method for operating a steering system according to claim 1, wherein the gear ratio is changed by de-energizing the switching gearbox in the event of a failure of the electric servomotor. ### Claim 13 (depends on 12) The method according to claim 12, wherein the changed gear ratio is compensated for by the superimposing gearbox.