# US 11,305,809 B2 · Motor control device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,305,809 B2 - Document ID: US11305809B2 - Status: Granted - Kind: B2 - Application number: 16/559,948 - Filed: 2019-09-04 - Published: 2019-12-26 - Granted: 2022-04-19 - Earliest claimed: 2017-03-06 - Assignees: Denso Corporation - Applicants: Denso Corporation - Inventors: Yuta Murakami; Toru Oiwa; Koji Isogai - Web page: https://patentgrep.com/patent/US11305809B2 ## CPC - B62D 5/0463: {calculating assisting torque from the motor based on driver input} - B62D 5/0481: {monitoring the steering system, e.g. failures} - B62D 6/00: Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits (means for initiating a change in direction B62D1/00; steering valves B62D5/06; combined with means for inclining the vehicle body or wheels on bends B62D9/00) - B62D 6/04: responsive only to forces disturbing the intended course of the vehicle, e.g. forces acting transversely to the direction of vehicle travel - G01L 3/04: wherein the torque-transmitting element comprises a torsionally-flexible shaft - H02P 6/08: Arrangements for controlling the speed or torque of a single motor (H02P6/10, H02P6/28 take precedence) - H02P 27/04: using variable-frequency supply voltage, e.g. inverter or converter supply voltage - H02P 29/032: Preventing damage to the motor, e.g. setting individual current limits for different drive conditions - B60W 30/08: {Active safety systems} predicting or avoiding probable or impending collision {or attempting to minimise its consequences} - B60W 2510/083: Torque - 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) - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS - B60W: CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT ## Abstract A motor control device controls driving of a motor, which outputs torque to a rack shaft as a load by rotation of a shaft fixed to a rotor. The motor control device has a rotation stress check unit for determining a rotation stress indicating a rotation stress, which is applied inversely from the load to a protection target member such as a shaft, bearing and oil seal related to the rotation of the shaft or torque transmission to the load. The rotation stress check unit determines the rotation stress is excessive based on that an absolute value of a rotation evaluation value exceeds a stress threshold value. The stress threshold value is set to be larger than an absolute value of an upper limit value realized in normal drive control. ## Claims ### Claim 1 A motor control device for controlling driving of a motor, which outputs torque to a load by rotation of a shaft fixed to a rotor, the motor control device comprising: a computer configured to determine a rotation stress abnormality indicating that a rotation stress, which is applied inversely from the load to a protection target member related to the rotation of the shaft or torque transmission to the load, is excessive based on that an absolute value of a rotation evaluation value exceeds a stress threshold value set to be larger than an upper limit value realized in normal drive control, the rotation evaluation value being an angular velocity, a rotation angular acceleration or a related value corresponding to the angular velocity or the rotation angular acceleration, wherein: the stress threshold value has at least two level values, which includes a short-term threshold value and one or more threshold value smaller than the short-term threshold value including a normal threshold value; the computer is configured to determine a short-term stress abnormality when the absolute value of the rotation evaluation value exceeds the short-term threshold value once; and the computer is configured to calculate a conversion value based on the absolute value of the rotation evaluation value when the absolute value of the rotation evaluation value exceeds the normal threshold value and determines an integrated stress abnormality when an integrated value of the conversion value exceeds a determination threshold value. ### Claim 2 (depends on 1) The motor control device according to claim 1, wherein: the computer is configured to integrates a reciprocal of a number of allowable repetitions as the conversion value at a time when the absolute value of the rotation evaluation value exceeds the normal threshold value. ### Claim 3 (depends on 1) The motor control device according to claim 1, further comprising: a memory configured to store the absolute value of the rotation evaluation value at a time when the computer determines that the absolute value exceeds the stress threshold value. ### Claim 4 (depends on 3) The motor control device according to claim 3, wherein: the memory is configured to store only a maximum value of the absolute value of the rotation evaluation value exceeding the stress threshold value. ### Claim 5 (depends on 3) The motor control device according to claim 3, wherein: the motor is provided to assist a steering torque in an electric power steering device in a vehicle. ### Claim 6 (depends on 1) The motor control device according to claim 1, wherein: the rotation evaluation value is the rotation angular acceleration. ### Claim 7 A method for controlling driving of a motor, the motor outputting torque to a load by rotation of a shaft fixed to a rotor, the method comprising: determining a rotation stress abnormality indicating that a rotation stress, which is applied inversely from the load to a protection target member related to the rotation of the shaft or torque transmission to the load, is excessive based on that an absolute value of a rotation evaluation value exceeds a stress threshold value set to be larger than an upper limit value realized in normal drive control, the rotation evaluation value being an angular velocity, a rotation angular acceleration or a related value corresponding to the angular velocity or the rotation angular acceleration, wherein the stress threshold value has at least two level values, which includes a short-term threshold value and one or more threshold value smaller than the short-term threshold value including a normal threshold value; determining a short-term stress abnormality when the absolute value of the rotation evaluation value exceeds the short-term threshold value once; and calculating a conversion value based on the absolute value of the rotation evaluation value when the absolute value of the rotation evaluation value exceeds the normal threshold value and determines an integrated stress abnormality when an integrated value of the conversion value exceeds a determination threshold value. ### Claim 8 (depends on 7) The method according to claim 7, further comprising integrating a reciprocal of a number of allowable repetitions as the conversion value at a time when the absolute value of the rotation evaluation value exceeds the normal threshold value. ### Claim 9 (depends on 7) The method according to claim 7, further comprising storing the absolute value of the rotation evaluation value at a time when the absolute value is determined to exceed the stress threshold value. ### Claim 10 (depends on 9) The method according to claim 9, wherein storing only a maximum value of the absolute value of the rotation evaluation value exceeding the stress threshold value. ### Claim 11 (depends on 9) The method according to claim 9, wherein the motor is provided to assist a steering torque in an electric power steering device in a vehicle. ### Claim 12 (depends on 7) The method according to claim 7, wherein the rotation evaluation value is the rotation angular acceleration.