Electric power steering device and control device of electric power steering device
AssigneeHitachi Automotive Systems Steering, Ltd.
InventorsYasuhito NAKAKUKI, Kazuya YAMANO
Life of this patent
Estimating the term…
Abstract
In order to suppress an electric power steering device from generating a contact noise due to operation of a mechanical stopper and a rack stopper, there is provided a control unit in which a command signal I0 applied to an electric motor used for assisting the steering power is calculated taking into consideration both a rack stopper side damping correction represented by a rack side damping correction signal Dr calculated in a rack side damping correction amount calculation part 21 and a mechanical stopper side damping correction represented by a mechanical side damping correction signal Dm calculated in a mechanical side damping correction amount calculation part 23.
Claims20
An electric power steering device comprising:
- a steering mechanism including a first shaft connected to a steering wheel, a second shaft connected to the first shaft through a torsion bar and a rack bar connected to the second shaft through a rack-and-pinion mechanism;
- a mechanical stopper including first and second stopper parts respectively provided by the first and second shafts, the first and second stopper parts being brought into contact to each other to suppress a further relative rotation between the first and second shafts when the first and second shafts make a given amount of relative rotation therebetween while twisting the torsion bar;
- an electric motor that provides the steering mechanism with a steering power for assisting a steering operation applied to the steering wheel;
- and
- a control unit for controlling the electric motor, the control unit including:
- a steering torque signal receiving part into which a steering torque signal produced in the steering mechanism is received;
- a steering angle signal receiving part into which a steering angle signal representing a steered angle of a steered road wheel is received;
- a torsion bar twist amount signal receiving part into which a torsion bar twist amount signal, which represents a twisted amount of the torsion bar, is received;
- a basic assist command signal calculation part by which a basic assist command signal for the electric motor is calculated based on the steering torque signal;
- a first damping signal calculation part that calculates a first damping signal when the steering angle signal represents that the steered angle is equal to or greater than a first given angle and the steering wheel is being turned further in the same direction, the first damping signal representing a damping force against a steering force produced by the electric motor when the steering wheel is turned further in the same direction;
- a second damping signal calculation part that calculates a second damping signal when the torsion bar twist amount signal represents that the torsion bar twist amount is equal to or greater than a second given angle and the steering wheel is being turned further in the same direction, the second damping signal representing a damping force against a steering force produced by the electric motor when the steering wheel is turned further in the same direction;
- a damping correction amount calculation part that calculates a damping correction amount, which is a correction amount of the basic assist command signal effected by the first and second damping signals, based on either one of the steering angle signal, a first control amount calculated based on the steering angle signal, the torsion bar twist amount signal and a second control amount calculated based on the torsion bar twist amount signal;
- and
- a motor command signal output part that outputs to the electric motor a command signal based on the basic assist command signal and the damping correction amount.
A control device for controlling an electric power steering device, the electric power steering device including a steering mechanism that includes a first shaft connected to a steering wheel, a second shaft connected to the first shaft through a torsion bar and a rack bar connected to the second shaft through a rack-and-pinion mechanism, a mechanical stopper that includes first and second stopper parts respectively provided by the first and second shafts wherein the first and second stopper parts are brought into contact to each other to suppress a relative rotation between the first and second shafts when the first and second shafts make a given relative rotation therebetween while twisting the torsion bar, and an electric motor that provides the steering mechanism with a steering power for assisting a steering operation applied to the steering wheel,
- said control device comprising:
- a steering torque signal receiving part into which a steering torque signal produced in the steering mechanism is received;
- a steering angle signal receiving part into which a steering angle signal representing a steered angle of a steered road wheel is received;
- a torsion bar twist amount signal receiving part into which a torsion bar twist amount signal, which represents a twisted amount of the torsion bar, is received;
- a basic assist command signal calculation part by which a basic assist command signal for the electric motor is calculated based on the steering torque signal;
- a first damping signal calculation part that calculates a first damping signal when the steering angle signal represents that the steered angle is equal to or greater than a first given angle and the steering wheel is being turned further in the same direction, the first damping signal representing a damping force against a steering force produced by the electric motor when the steering wheel is turned further in the same direction;
- a second damping signal calculation part that calculates a second damping signal when the torsion bar twist amount signal represents that the torsion bar twist amount is equal to or greater than a second given angle and the steering wheel is being turned further in the same direction, the second damping signal representing a damping force against a steering force produced by the electric motor when the steering wheel is turned further in the same direction;
- a damping correction amount calculation part that calculates a damping correction amount, which is a correction amount of the basic assist command signal effected by the first and second damping signals, based on either one of the steering angle signal, a first control amount calculated based on the steering angle signal, the torsion bar twist amount signal and a second control amount calculated based on the torsion bar twist amount signal;
- and
- a motor command signal output part that outputs to the electric motor a command signal based on the basic assist command signal and the damping correction amount.
Dependencies are inferred from the claim text.