Electric power steering device

Patent metadata

Field	Value
Publication number	US-11370477-B2
Application number	US-201916701592-A
Country	US
Kind code	B2
Filing date	Dec 3, 2019
Priority date	Dec 5, 2018
Publication date	Jun 28, 2022
Grant date	Jun 28, 2022

Abstract

A calculator or an electronic control unit (ECU) calculates an instruction value of a column assist torque and a rack assist torque output from a column actuator, or a column motor, and a rack actuator, or a rack motor, based at least on a torsion torque. The calculator includes a base assist controller, a stabilization controller, and an adder. The base assist controller individually or commonly calculates a base assist torque based on the torsion torque. The stabilization controller individually or commonly calculates a stabilization torque for stabilizing a steering system. The adder performs addition of the base assist torque and the stabilization torque.

First claim

What is claimed is:

1. An electric power steering device for generating a steering assist torque by using a plurality of actuators in a steering system of a vehicle, in which a steering torque input to a steering wheel is transmitted to a tire via a steering shaft in a column, an intermediate shaft and a rack, the electric power steering device comprising:
a column actuator disposed on a column side of the intermediate shaft and configured to output a column assist torque;
a rack actuator disposed on a rack side of the intermediate shaft and configured to output a rack assist torque;
one or more torque sensors respectively configured to detect a torsion torque applied to the steering shaft or to the intermediate shaft; and
one or more calculators respectively configured to calculate an instruction value of the column assist torque or the rack assist torque based on the torsion torque detected by the one or more torque sensors, wherein
the one or more calculators include:
a base assist controller configured to calculate a base assist torque as a main component of the column assist torque and a main component of the rack assist torque, based on the torsion torque;
a stabilization controller configured to calculate a stabilization torque for stabilizing a steering system as a sub-component of the column assist torque and a sub-component of the rack assist torque; and
an adder configured to add the base assist torque and the stabilization torque,

wherein the base assist controller separately calculates individual base assist torques for each of the column actuator and the rack actuator, or the base assist controller calculates a common base assist torque for both of the column actuator and the rack actuator, and
wherein the stabilization controller separately calculates individual stabilization torques for each of the column actuator and the rack actuator, or the stabilization controller calculates a common stabilization torque for both of the column actuator and the rack actuator.

2. The electric power steering device of claim 1 , further comprising:
a response compensator, provided in theone or more calculators, configured to compensate a difference of a gain or a phase of rack response characteristics with respect to column response characteristics in a preset frequency range, the column response characteristics including response characteristics of the torsion torque in response to a change of the column assist torque and the rack response characteristics including response characteristics of the torsion torque in response to a change of the rack assist torque, wherein
a post-process value of a component of the column assist torque, which is obtained by processing of the response compensator, is output as a value of a component of the rack assist torque, regarding at least one of the base assist torque and the stabilization torque.

3. The electric power steering device of claim 2 , further comprising:
a rack assist compensation controller, in at least one calculator, configured to calculate a rack assist compensation torque regarding the rack assist torque for an improvement of at least one of (a) a steering feel, (b) a vehicle behavior convergence or a steering wheel behavior convergence, (c) a steering wheel neutrality recovery character at a hands-off time, or (d) a vehicle motion, wherein
the rack assist compensation torque is added, without undergoing processing of the response compensator, to a post-process value of the component of the column assist torque which is derived from processing by the response compensator.

4. The electric power steering device of claim 1 , wherein
the one or more calculators adjust the output of the stabilization controller according to an assist gain value of the base assist controller.

5. The electric power steering device of claim 1 , wherein
a plurality of the calculators are provided.

6. The electric power steering device of claim 5 , wherein
the plurality of the calculators are coupled by a communication line with each other for communication of information.

Assignees

• Denso Corp
• Nagoya Inst Tech

Inventors

• Kuramitsu Shuji
• Otake Hiroyasu
• Kano Ryo
• Morita Yoshifumi
• Watanabe Hironao
• Kato Takayuki

Classifications

• B62D5/04 Primary

  electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear · CPC title

• B62D5/0463

  calculating assisting torque from the motor based on driver input · CPC title

• B62D5/063

  Pump driven by vehicle engine (B62D5/065 takes precedence) · CPC title

• B62D6/008

  Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications · CPC title

• B62D5/0472 Primary

  for damping vibrations · CPC title