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US 2018/0022379 A1Published application
Power steering device and control device therefor
AssigneeHitachi Automotive Systems, Ltd.
InventorsMitsuo SASAKI, Makoto GOTO
Life of this patent
Estimating the term…
Abstract
Disclosed is a power steering device 1 having a control unit 33 equipped with an abnormality detection circuit 50. The abnormality detection circuit 50 is configured to judge the occurrence of an abnormality in the power steering device when a peak level Trp of a frequency component of a steering torque Tr etc. that periodically changes in a frequency range of 20 to 25 Hz becomes higher than a predetermined value.
Claims18
A power steering device, comprising:
- a steering unit having:
- a steering shaft rotatable with rotation of a steering wheel of a vehicle;
- and a rack bar made of an iron-based metal material and axially movable in response to rotation of the steering shaft;
- an electric motor arranged to apply a steering force to the steering unit;
- a ball-screw mechanism arranged as a reduction unit between the steering unit and the electric motor so as to transmit a toque of the electric motor to the steering unit, the ball-screw mechanism including:
- a steerable wheel-side ball screw groove helically recessed in an outer circumferential surface of the rack bar;
- a nut made of an iron-based metal material in an annular shape and arranged to surround the rack bar and be rotatable relative to the rack bar;
- a nut-side ball screw groove helically recessed in an inner circumferential surface of the nut to define a ball circulation channel with the steerable wheel-side ball screw groove;
- a plurality of balls made of an iron-based metal material and arranged in the ball circulation channel;
- and a circulation member connecting one end to the other end of the ball circulation channel so as to allow circulation of the plurality of balls from the one end to the other end of the ball circulation channel;
- and
- a control unit arranged to drive and control the electric motor,
- the control unit including:
- a steering torque signal receiving section that receives a signal indicative of a steering torque generated in the steering unit;
- a command signal calculating section that calculates an electric motor command signal for drive control of the electric motor based on the steering torque signal;
- and
- an abnormality detection circuit configured to use the steering torque, the electric motor command signal or a motor current flowing in the electric motor as steering force information and judge the occurrence of an abnormality in the power steering device when a value of the steering force information periodically changes in a predetermined frequency range, which is higher than or equal to a first frequency and lower than or equal to a second frequency, and the value of the steering force information in the predetermined frequency range becomes higher than a predetermined value.
14 more elements
A control device for a power steering device,
- the power steering device comprising:
- a steering unit having:
- a steering shaft rotatable with rotation of a steering wheel of a vehicle;
- and a rack bar made of an iron-based metal material and axially movable in response to rotation of the steering shaft;
- an electric motor arranged to apply a steering force to the steering unit;
- and
- a ball-screw mechanism arranged as a reduction unit between the steering unit and the electric motor so as to transmit a toque of the electric motor to the steering unit, the ball-screw mechanism including:
- a steerable wheel-side ball screw groove helically recessed in an outer circumferential surface of the rack bar;
- a nut made of an iron-based metal material in an annular shape and arranged to surround the rack bar and be rotatable relative to the rack bar;
- a nut-side ball screw groove helically recessed in an inner circumferential surface of the nut to define a ball circulation channel with the steerable wheel-side ball screw groove;
- a plurality of balls made of an iron-based metal material and arranged in the ball circulation channel;
- and a circulation member connecting one end to the other end of the ball circulation channel so as to allow circulation of the plurality of balls from the one end to the other end of the ball circulation channel,
- the control device comprising:
- a steering torque signal receiving section that receives a signal indicative of a steering torque generated in the steering unit;
- a command signal calculating section that calculates an electric motor command signal for drive control of the electric motor based on the steering torque signal;
- and
- an abnormality detection circuit configured to use the steering torque, the electric motor command signal or a motor current flowing in the electric motor as steering force information and judge the occurrence of an abnormality in the power steering device when a value of the steering force information periodically changes in a predetermined frequency range, which is higher than or equal to a first frequency and lower than or equal to a second frequency, and the value of the steering force information in the predetermined frequency range becomes higher than a predetermined value.
14 more elements
Dependencies are inferred from the claim text.