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US 2017/0282969 A1Published application
Power steering device
AssigneeHitachi Automotive Systems Steering, Ltd.
InventorMitsuo SASAKI
Life of this patent
Estimating the term…
Abstract
A power steering apparatus includes: a steering load average value calculating circuit 39 which calculates a steering torque average value Trav which is the average value of steering torque Tr within a predetermined interval of time; and an abnormality detection circuit 40 which compares steering torque average value Trav with a specified steering torque value Trrf and detects the abnormality of the apparatus when steering torque average value Trav is larger than the specified value.
Claims19
A power steering apparatus comprising:
- a steering mechanism formed of an iron-series metallic material and which steers steerable wheels in accordance with a steering operation of a steering wheel;
- an electrically driven motor which provides a steering force for the steering mechanism;
- a speed reduction mechanism formed of the iron-series metallic material, interposed between the steering mechanism and the electrically driven motor, and which transmits a revolution force of the electrically driven motor to the steering mechanism;
- a torque sensor which detects a steering torque generated in the steering mechanism;
- a control unit which calculates a motor command current drivingly controlling the electrically driven motor on a basis of the steering torque and outputs the motor command current to the electrically driven motor;
- a steering load average value calculating circuit installed in the control unit and which calculates an average value of a steering load corresponding value which corresponds to any one of the steering torque within a predetermined interval of time, the motor command current, and a motor actual current actually flowing through the electrically driven motor;
- and
- an abnormality detection circuit installed in the control unit, which compares the average value of the steering load corresponding value with a specified value stored in the control unit, and detects an abnormality of the apparatus when the average value is larger than the specified value, wherein the steering mechanism includes a rack bar which axially moves due to a revolution of a steering wheel to steer the steerable wheels and the speed reduction mechanism includes a ball-screw mechanism having:
- a rack bar side ball screw groove installed on an outer peripheral side of the rack bar and having a spiral groove shape;
- a nut annularly installed to enclose the rack bar and rotatably installed with respect to the rack bar;
- a nut side ball screw groove installed on an inner peripheral side of the nut, having a spiral groove shape, and constituting a ball circulation groove together with a steering shaft side ball screw;
- a plurality of balls installed within the ball circulation groove;
- and a circulation member installed at an outer side of a radial direction of the nut and connecting one end side of the ball groove and the other side thereof in order for the plurality of balls to enable a circulation from the one end side of the ball circulation groove to the other end side, and a transmission mechanism which transmits the revolution of the electrically driven motor to the nut.
10 more elements
A power steering apparatus comprising:
- a steering mechanism formed of an iron-series metallic material and which steers steerable wheels in accordance with a steering operation of a steering wheel;
- an electrically driven motor which provides a steering force for the steering mechanism;
- a speed reduction mechanism formed of the iron-series metallic material, interposed between the steering mechanism and the electrically driven motor, and which transmits a revolution force of the electrically driven motor to the steering mechanism;
- a torque sensor which detects a steering torque generated in the steering mechanism;
- a control unit which calculates a motor command current drivingly controlling the electrically driven motor on a basis of the steering torque and outputs the motor command current to the electrically driven motor;
- and
- an abnormality detection circuit, installed in the control unit, which compares a steering load corresponding value which corresponds to any one of the steering torque within a predetermined interval of time, the motor command current, and a motor actual current actually flowing through the electrically driven motor with a specified value stored in the control unit, and which detects an abnormality of the apparatus when a frequency that the steering load corresponding value exceeds the specified value is larger than a predetermined value, wherein the steering mechanism includes a rack bar which axially moves due to a revolution of a steering wheel to steer the steerable wheels and the speed reduction mechanism includes a ball-screw mechanism having:
- a rack bar side ball screw groove installed on an outer peripheral side of the rack bar and having a spiral groove shape;
- a nut annularly installed to enclose the rack bar and rotatably installed with respect to the rack bar;
- a nut side ball screw groove installed on an inner peripheral side of the nut, having a spiral groove shape, and constituting a ball circulation groove together with a steering shaft side ball screw;
- a plurality of balls installed within the ball circulation groove;
- and a circulation member installed at an outer side of a radial direction of the nut and connecting one end side of the ball groove and the other side thereof in order for the plurality of balls to enable a circulation from the one end side of the ball circulation groove to the other end side, and a transmission mechanism which transmits the revolution of the electrically driven motor to the nut.
9 more elements
A power steering apparatus comprising:
- a steering mechanism formed of an iron-series metallic material and which steers steerable wheels in accordance with a steering operation of a steering wheel;
- an electrically driven motor which provides a steering force for the steering mechanism;
- a speed reduction mechanism interposed between the steering mechanism and the electrically driven motor and which transmits a revolution force of the electrically driven motor to the steering mechanism;
- a torque sensor which detects a steering torque generated in the steering mechanism;
- a control unit which calculates a motor command current drivingly controlling the electrically driven motor on a basis of the steering torque and outputs the motor command current to the electrically driven motor;
- a steering load average value calculating circuit installed in the control unit and which calculates an average value of a steering load corresponding value which is any one of the steering torque within a predetermined interval of time, the motor command current, and a motor actual current actually flowing through the electrically driven motor;
- and
- an abnormality detection circuit installed in the control unit, which compares the average value of the steering load corresponding value with a specified value stored in the control unit, and which detects an abnormality of the apparatus when the average value is larger than the specified value, wherein the steering mechanism includes a rack bar which axially moves due to a revolution of a steering wheel to steer the steerable wheels and the speed reduction mechanism includes a ball-screw mechanism having:
- a rack bar side ball screw groove installed on an outer peripheral side of the rack bar and having a spiral groove shape;
- a nut annularly installed to enclose the rack bar and rotatably installed with respect to the rack bar;
- a nut side ball screw groove installed on an inner peripheral side of the nut, having a spiral groove shape, and constituting a ball circulation groove together with a steering shaft side ball screw;
- a plurality of balls installed within the ball circulation groove;
- and a circulation member installed at an outer side of a radial direction of the nut and connecting one end side of the ball groove and the other side thereof in order for the plurality of balls to enable a circulation from the one end side of the ball circulation groove to the other end side, and a transmission mechanism which transmits the revolution of the electrically driven motor to the nut.
10 more elements
Dependencies are inferred from the claim text.