# US 8,783,118 B2 · Control unit for electric power steering device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,783,118 B2 - Document ID: US8783118B2 - Status: Granted - Kind: B2 - Application number: 13/073,556 - Filed: 2011-03-28 - Published: 2011-10-06 - Granted: 2014-07-22 - Earliest claimed: 2010-03-31 - Assignees: Honda Motor Co., Ltd. - Applicants: Shinichiro Kato; Takeshi Wakabayashi; Katsumi Sahoda; Tsuyoshi Tsuda; Hiroyuki Kaneta - Inventors: Shinichiro Kato; Takeshi Wakabayashi; Katsumi Sahoda; Tsuyoshi Tsuda; Hiroyuki Kaneta - Web page: https://patentgrep.com/patent/US8783118B2 ## CPC - B62D 6/10: characterised by means for sensing {or determining} torque - B62D 5/0409: {Electric motor acting on the steering column} - B62K 5/01: Motorcycles with four or more wheels (specially adapted for disabled riders B62K5/003) - B62K 5/027: Motorcycles with three wheels (specially adapted for disabled riders B62K5/023) - B62K 5/08: with steering devices acting on two or more wheels - B62K 21/00: Steering devices - 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) - B62K: CYCLES; CYCLE FRAMES; CYCLE STEERING DEVICES; RIDER-OPERATED TERMINAL CONTROLS SPECIALLY ADAPTED FOR CYCLES; CYCLE AXLE SUSPENSIONS; CYCLE SIDECARS, FORECARS, OR THE LIKE ## Abstract A bending load acting on a steering shaft only with a magnetostrictive torque sensor, without separately providing a sensor for detecting the bending moment. A storage unit stores, as an initial characteristic curve formed from initial detection values, a characteristic curve formed from detection values of each of a first detection coil and a second detection coil when only twisting torque is applied to a steering shaft. A bending load detector provided in an ECU detects a bending load amount acting on the steering shaft based on a difference between each detection value of the first and second detection coils and the initial detection value on the initial characteristic curve corresponding to the detection value. ## Claims ### Claim 1 A control unit for an electric power steering device provided with a first magnetostrictive film and a second magnetostrictive film with magnetic anisotropic properties opposite in direction to each other, each formed circumferentially on a surface of a steering shaft, and a first detection coil and a second detection coil provided around the first magnetostrictive film and the second magnetostrictive film, respectively, for detecting a twisting torque applied to the steering shaft based on an actual detection value of each of the first detection coil and the second detection coil to adjust an assist amount for the steering shaft, the control unit further comprising: a storage unit for storing an initial characteristic curve C1 formed from an initial detection value Z1 of the first detection coil when only the twisting torque T1 is applied to the steering shaft, and an initial characteristic curve C2 formed from an initial detection value Z2 of the second detection coil when only the twisting torque T1 is applied to the steering shaft; and a characteristic curve C3 being formed from the actual detection value P1 of first detection coil, and a characteristic curve C4 being formed from the actual detection value P2 of the second detection coil; and a bending load detector for detecting the bending load amount acting on the steering shaft based on a difference ΔS between the actual detection value P1 on the characteristic curve C3 and the initial detection value Z1 on the initial characteristic curve C1, and on a difference ΔS between the actual detection value P2 on the characteristic curve C3 and the initial detection value Z2 on the initial characteristic curve C2. ### Claim 2 (depends on 1) The control unit for the electric power steering device according to claim 1, wherein, when the twisting torque T1 is applied in one direction from a neutral position of the steering shaft, each of the initial characteristic curves C1, C2 has an upwardly convex curve shape that reaches a peak at a predetermined torque T1, on the other hand, when the twisting torque T1 is applied in an opposite direction from the neutral position of the steering shaft, each of the initial characteristic curves C1, C2 has a gradually decaying curve shape, wherein the initial characteristic curves C1, C2 of the first detection coil and the second detection coil have opposite characteristics with the initial detection values Z1, Z2 being symmetric with respect to the neutral position of the steering shaft, and wherein the bending load detector detects the twisting torque T1 corresponding to each of the actual detection values P1, P2 detected by the first detection coil and the second detection coil from a range having the gradually decaying curve shape on one of the initial characteristic curve C1 of the first detection coil and the initial characteristic curve C2 of the second detection coil, and obtains each of the initial detection values Z1, Z2 corresponding to the detected twisting torque T1 from a range having the upwardly convex curve shape on the other initial characteristic curve to detect the bending load amount based on the difference ΔS between the initial detection values Z1, Z2 and the actual detection values P1, P2 detected by the first detection coil or the second detection coil. ### Claim 3 (depends on 1) The control unit for the electric power steering device according to claim 1, and further including an assist characteristic deciding portion that determines a vehicle operating condition based on the bending load amount detected by the bending load detector, and adjusts the assist amount for the steering shaft according to the operating condition as determined. ### Claim 4 (depends on 2) The control unit for the electric power steering device according to claim 2, and further including an assist characteristic deciding portion that determines a vehicle operating condition based on the bending load amount detected by the bending load detector, and adjusts the assist amount for the steering shaft according to the operating condition as determined. ### Claim 5 (depends on 3) The control unit for the electric power steering device according to claim 3, wherein the assist characteristic deciding portion determines the vehicle operating condition based on the bending load amount detected by the bending load detector and a vehicle speed value detected by a vehicle speed sensor for detecting vehicle speed, and adjusts the assist amount for the steering shaft according to the operating condition as determined. ### Claim 6 (depends on 4) The control unit for the electric power steering device according to claim 4, wherein the assist characteristic deciding portion determines the vehicle operating condition based on the bending load amount detected by the bending load detector, a vehicle speed value of the vehicle speed sensor when the bending load amount is detected, and the values of the twisting torque T1 from the first detection coil and the second detection coil when the bending load amount is detected, and adjusts the assist amount for the steering shaft according to the operating condition as determined. ### Claim 7 (depends on 6) The control unit for the electric power steering device according to claim 6, wherein the assist characteristic deciding portion decides the assist amount for the steering shaft based on the vehicle speed value of the vehicle speed sensor and the values of the twisting torque T1 from the first detection coil and the second detection coil, and wherein, when the bending load amount is detected by the bending load detector, the assist characteristic deciding portion determines the vehicle operating condition based on the bending load amount detected by the bending load detector, and the vehicle speed value of the vehicle speed sensor when the bending load amount is detected, and adjusts the decided assist amount for the steering shaft according to the operating condition as determined. ### Claim 8 (depends on 5) The control unit for the electric power steering device according to claim 5, wherein the assist characteristic deciding portion performs a damper feel control for the steering shaft based on the bending load amount detected by the bending load detector, the vehicle speed value of the vehicle speed sensor when the bending load amount is detected, and the values of the twisting torque T1 from the first detection coil and the second detection coil when the bending load amount is detected. ### Claim 9 (depends on 6) The control unit for the electric power steering device according to claim 6, wherein the assist characteristic deciding portion performs a damper feel control for the steering shaft based on the bending load amount detected by the bending load detector, the vehicle speed value of the vehicle speed sensor when the bending load amount is detected, and the values of the twisting torque T1 from the first detection coil and the second detection coil when the bending load amount is detected. ### Claim 10 (depends on 3) The control unit for the electric power steering device according to claim 3, wherein the assist characteristic deciding portion determines the vehicle operating condition based on the bending load amount detected by the bending load detector, a vehicle speed value detected by a vehicle speed sensor for detecting vehicle speed, the values of the twisting torque T1 from the first detection coil and the second detection coil, and a tilt angle value from a tilt angle sensor for detecting a vehicle tilt angle to adjust the assist amount for the steering shaft according to the operating condition as determined and to perform a damper feel control. ### Claim 11 A control unit for an electric power steering device comprising: a steering shaft; a first magnetostrictive film and a second magnetostrictive film with magnetic anisotropic properties opposite in direction to each other, each formed circumferentially on a surface of the steering shaft; a first detection coil and a second detection coil provided around the first magnetostrictive film and the second magnetostrictive film, respectively, for detecting a twisting torque T1 applied to the steering shaft based on actual detection values of the first detection coil and the second detection coil to adjust an assist amount for the steering shaft; a storage unit for storing: an initial characteristic curve C1 formed from an initial detection value Z1 of the first detection coil when only the twisting torque T1 is applied to the steering shaft, and an initial characteristic curve C2 formed from an initial detection value Z2 of the second detection coil when only the twisting torque T1 is applied to the steering shaft; and a characteristic curve C3 being formed from the actual detection value P1 of first detection coil, and a characteristic curve C4 being formed from the actual detection value P2 of the second detection coil; and a bending load detector for detecting the bending load amount acting on the steering shaft based on a difference ΔS between the actual detection value P1 on the characteristic curve C3 and the initial detection value Z1 on the initial characteristic curve C1, and on a difference ΔS between the actual detection value P2 on the characteristic curve C3 and the initial detection value Z2 on the initial characteristic curve C2. ### Claim 12 (depends on 11) The control unit for the electric power steering device according to claim 11, wherein, when the twisting torque T1 is applied in one direction from a neutral position of the steering shaft, each of the initial characteristic curves C1, C2 has an upwardly convex curve shape that reaches a peak at a predetermined torque T1, on the other hand, when the twisting torque T1 is applied in an opposite direction from the neutral position of the steering shaft, each of the initial characteristic curves C1, C2 has a gradually decaying curve shape, wherein the initial characteristic curves C1, C2 of the first detection coil and the second detection coil have opposite characteristics with the initial detection values Z1, Z2 being symmetric with respect to the neutral position of the steering shaft, and wherein the bending load detector detects the twisting torque T1 corresponding to each of the actual detection values P1, P2 detected by the first detection coil and the second detection coil from a range having the gradually decaying curve shape on one of the initial characteristic curve C1 of the first detection coil and the initial characteristic curve C2 of the second detection coil, and obtains each of the actual detection values P1, P2 corresponding to the detected twisting torque T1 from a range having the upwardly convex curve shape on the other initial characteristic curve to detect the bending load amount based on the difference ΔS between the initial detection values Z1, Z2 and the actual detection values P1, P2 detected by the first detection coil or the second detection coil. ### Claim 13 (depends on 11) The control unit for the electric power steering device according to claim 11, and further including the assist characteristic deciding portion that determines a vehicle operating condition based on the bending load amount detected by the bending load detector, and adjusts an assist amount for the steering shaft according to the operating condition as determined. ### Claim 14 (depends on 12) The control unit for the electric power steering device according to claim 12, and further including the assist characteristic deciding portion that determines a vehicle operating condition based on the bending load amount detected by the bending load detector, and adjusts an assist amount for the steering shaft according to the operating condition as determined. ### Claim 15 (depends on 13) The control unit for the electric power steering device according to claim 13, wherein the assist characteristic deciding portion determines the vehicle operating condition based on the bending load amount detected by the bending load detector and a vehicle speed value detected by a vehicle speed sensor for detecting vehicle speed, and adjusts the assist amount for the steering shaft according to the operating condition as determined. ### Claim 16 (depends on 14) The control unit for the electric power steering device according to claim 14, wherein the assist characteristic deciding portion determines the vehicle operating condition based on the bending load amount detected by the bending load detector, a vehicle speed value of the vehicle speed sensor when the bending load amount is detected, and the values of the twisting torque T1 from the first detection coil and the second detection coil when the bending load amount is detected, and adjusts the assist amount for the steering shaft according to the operating condition as determined. ### Claim 17 (depends on 16) The control unit for the electric power steering device according to claim 16, wherein the assist characteristic deciding portion decides the assist amount for the steering shaft based on the vehicle speed value of the vehicle speed sensor and the values of the twisting torque T1 from the first detection coil and the second detection coil, and wherein, when the bending load amount is detected by the bending load detector, the assist characteristic deciding portion determines the vehicle operating condition based on the bending load amount detected by the bending load detector, and the vehicle speed value of the vehicle speed sensor when the bending load amount is detected, and adjusts the decided assist amount for the steering shaft according to the operating condition as determined. ### Claim 18 (depends on 15) The control unit for the electric power steering device according to claim 15, wherein the assist characteristic deciding portion performs a damper feel control for the steering shaft based on the bending load amount detected by the bending load detector, the vehicle speed value of the vehicle speed sensor when the bending load amount is detected, and the values of the twisting torque T1 from the first detection coil and the second detection coil when the bending load amount is detected. ### Claim 19 (depends on 16) The control unit for the electric power steering device according to claim 16, wherein the assist characteristic deciding portion performs a damper feel control for the steering shaft based on the bending load amount detected by the bending load detector, the vehicle speed value of the vehicle speed sensor when the bending load amount is detected, and the values of the twisting torque T1 from the first detection coil and the second detection coil when the bending load amount is detected. ### Claim 20 (depends on 13) The control unit for the electric power steering device according to claim 13, wherein the assist characteristic deciding portion determines the vehicle operating condition based on the bending load amount detected by the bending load detector, a vehicle speed value detected by a vehicle speed sensor for detecting vehicle speed, the values of the twisting torque T1 from the first detection coil and the second detection coil, and a tilt angle value from a tilt angle sensor for detecting a vehicle tilt angle to adjust the assist amount for the steering shaft according to the operating condition as determined and to perform a damper feel control.