# US 10,246,127 B2 · Rotational angle detecting device and electric power steering device using the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,246,127 B2 - Document ID: US10246127B2 - Status: Granted - Kind: B2 - Application number: 14/631,260 - Filed: 2015-02-25 - Published: 2015-08-27 - Granted: 2019-04-02 - Earliest claimed: 2014-02-27 - Assignees: Denso Corporation - Applicants: Denso Corporation - Inventors: Takaharu Kozawa; Toshihiro Fujita - Web page: https://patentgrep.com/patent/US10246127B2 ## CPC - B62D 5/0484: {for reaction to failures, e.g. limp home} - B62D 5/046: {Controlling the motor} - B62D 5/0463: {calculating assisting torque from the motor based on driver input} - B62D 5/0481: {monitoring the steering system, e.g. failures} - B62D 15/021: {Determination of steering angle} - B62D 15/0235: {by measuring or deriving directly at the electric power steering motor} - G01B 7/30: for measuring angles or tapers; for testing the alignment of axes - 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) - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS ## Abstract A rotational angle detecting device has a detecting element that detects a rotating magnetic field of a magnet that is variable according to a rotation of a motor. A rotational angle calculator calculates a rotational angle and a rotation number. A power supply failure determining circuit has a volatile memory that stores power supply failure information indicating that power supply failure occurs in which electric power is not supplied to the rotational angle detecting device from a battery. A communication portion outputs the rotational information and output information corresponding to the power supply failure information to the controller. The communication portion receives a notifying signal after the controller receives the output information indicating that the power supply failure occurs. The volatile memory stores the power supply failure information indicating that the power supply failure occurs after the power supply failure occurs until the communication portion receives the notifying signal. ## Claims ### Claim 1 A rotational angle detecting device that is directly supplied with electric power from a battery and outputs rotational information of a detection object to a controller, the controller being provided separately from the rotation angle detecting device and being connected to the battery through an ignition switch that switches power supply to the controller from the battery, the rotational angle detecting device comprising: a sensor that detects a detection value that is variable according to a rotation of the detection object; a calculator that calculates the rotational information based on the detection value detected by the sensor; a memory that stores power supply failure information indicating whether power supply failure occurs in which electric power is not supplied to the rotational angle detecting device from the battery; and a communication portion that outputs the rotational information and output information corresponding to the power supply failure information stored in the memory to the controller, the communication portion receiving a notifying signal from the controller that outputs the notifying signal after the controller receives the output information indicating that the power supply failure occurs, wherein the memory stores the power supply failure information indicating that the power supply failure occurs, during a period after the power supply failure occurs until the communication portion receives the notifying signal from the controller, and the controller is only powered from the battery through the ignition switch. ### Claim 2 (depends on 1) The rotational angle detecting device according to claim 1, wherein the memory is a volatile memory that returns the power supply failure information to an initial value indicating that the power supply failure occurs, when the power supply failure occurs. ### Claim 3 (depends on 1) The rotational angle detecting device according to claim 1, wherein the detection object is a motor, the rotational information includes a rotational angle and a number of rotations of the motor, and the calculator continues calculating at least the number of rotations while the ignition switch is turned off. ### Claim 4 (depends on 3) The rotational angle detecting device according to claim 3, wherein the calculator calculates the number of rotations of the motor at least one time at the rotational angle of less than 180°. ### Claim 5 (depends on 1) The rotational angle detecting device according to claim 1, wherein the power supply failure information is represented using multiple bits. ### Claim 6 (depends on 1) The rotational angle detecting device according to claim 1, wherein the communication portion includes a serial interface. ### Claim 7 (depends on 6) The rotational angle detecting device according to claim 6, wherein the communication portion outputs the output information represented using multiple bits having a bit number twice or more times of a bit number of the power supply failure information. ### Claim 8 (depends on 1) An electric power steering device comprising: a motor that outputs an assistance torque to assist steering of a steering member by a driver; the rotational angle detecting device according to claim 1, the detection object for the rotational angle detecting device being the motor; and an electric control unit that includes the controller controlling the motor. ### Claim 9 (depends on 8) The electric power steering device according to claim 8, wherein the controller calculates a rotational angle of a steering shaft connected to the steering member based on the rotational information. ### Claim 10 (depends on 9) The electric power steering device according to claim 9, wherein the controller executes a fail-safe process when the controller receives the output information indicating that the power supply failure occurs. ### Claim 11 (depends on 10) The electric power steering device according to claim 10, wherein the controller outputs the notifying signal upon executing the fail-safe process. ### Claim 12 (depends on 10) The electric power steering device according to claim 10, wherein the controller learns and stores a neutral position of the steering member, and the controller calculates the rotational angle of the steering shaft using the neutral position of the steering member and the rotational information when the ignition switch is turned on and the controller receives the output information indicating that the power supply failure does not occur. ### Claim 13 (depends on 12) The electric power steering device according to claim 12, wherein the controller relearns the neutral position of the steering member as the fail-safe process to calculate the rotational angle of the steering shaft when the ignition switch is turned on and the controller receives the output information indicating that the power supply failure occurs. ### Claim 14 (depends on 1) The rotational angle detecting device of claim 1, wherein the notifying signal received by the communication portion from the controller indicates that the controller has completed detecting a neutral position of the detection object. ### Claim 15 A rotational angle detecting system, comprising: a rotational angle detecting device that is directly supplied with electric power from a battery; and a controller provided separately from the rotation angle detecting device and being connected to the battery through an ignition switch that switches power supply to the controller from the battery, wherein the rotational angle detecting device includes a sensor that detects a detection value that is variable according to a rotation of a detection object; a calculator that calculates a rotational information of the detection object based on the detection value detected by the sensor; a memory that stores power supply failure information indicating an occurrence of a power supply failure in which electric power is not supplied to the rotational angle detecting device from the battery; and a communication portion that outputs the rotational information to the controller, the memory is a volatile memory that, when the power supply failure occurs, sets the power supply failure information to an initial value indicating the occurrence of the power supply failure, the rotational angle detecting device is programmed to: determine whether the power supply failure information stored in the memory indicates the occurrence of a power supply failure, after determining that the power supply failure information stored in the memory indicates the occurrence of a power supply failure, output the power supply failure information to the controller and receive a notifying signal from the controller, and after receiving the notifying signal from the controller, set the supply failure information to a normal value indicating no occurrence of the power supply failure, and the controller is programmed to: receive the power supply failure information indicating the occurrence of a power supply failure from the rotational angle detecting device, after receiving the power supply failure information, detect a neutral position of the detection object, and after detecting the neutral position of the detecting object, output the notifying signal to the rotational angle detecting device. ### Claim 16 A rotational angle detecting system, comprising: a rotational angle detecting device that is directly supplied with electric power from a battery; and a controller provided separately from the rotation angle detecting device and being connected to the battery through an ignition switch that switches power supply to the controller from the battery, wherein the rotational angle detecting device includes a sensor that detects a detection value that is variable according to a rotation of a detection object; a calculator that calculates a rotational information of the detection object based on the detection value detected by the sensor; a memory that stores power supply failure information indicating an occurrence of a power supply failure in which electric power is not supplied to the rotational angle detecting device from the battery; and a communication portion that outputs the rotational information to the controller, the memory is a volatile memory that, when the power supply failure occurs, sets the power supply failure information to an initial value indicating the occurrence of the power supply failure, the rotational angle detecting device is programmed to: upon the occurrence of a power supply failure, set the power supply failure information in the memory to the initial value indicating the occurrence of a power supply failure, after setting the power supply failure information in the memory indicating the occurrence of a power supply failure, output the power supply failure information to the controller and receive a notifying signal from the controller, and after receiving the notifying signal from the controller, set the supply failure information to a normal value indicating no occurrence of the power supply failure, and the controller is programmed to: receive the power supply failure information indicating the occurrence of a power supply failure from the rotational angle detecting device, after receiving the power supply failure information, detect a neutral position of the detection object, and after detecting the neutral position of the detecting object, output the notifying signal to the rotational angle detecting device.