POWER STEERING DEVICE

• US 20110209939A1
• Filed: 12/26/2008
• Published: 09/01/2011
• Est. Priority Date: 12/26/2008
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Ono, Kimiaki, Kushiro, Ikuo
• Granted Patent: US 9,090,280 B2
• Time in Patent Office: Days
• US Class Current: 180/447
• CPC Class Codes: B62D 5/008 Changing the transfer ratio between the steering wheel and the steering gear by variable supply of energy, e.g. by using a superposition gear
• CPC Class Codes: B62D 6/008 Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications

Abstract

A power steering device is mounted on a vehicle and includes a variable transmission ratio mechanism, a torque applying unit, and an applied friction torque changing unit. The torque applying unit sets an applied friction torque applied to the steering wheel and performs a control of applying the applied friction torque to the steering wheel. The applied friction torque changing unit changes the applied friction torque based on the transmission ratio of the variable transmission ratio mechanism.

Claims

1. A power steering device mounted on a vehicle, comprising:

a variable transmission ratio mechanism which changes a transmission ratio between a steering angle and a steered angle;

a friction torque setting unit which sets a friction torque applied to a steering wheel based on information indicating a situation of the vehicle;

a target steering angle setting unit which sets a target steering angle based on the friction torque;

a torque applying unit which sets an applied friction torque based on a deviation between the target steering angle and the steering angle, and which performs a control of applying the applied friction torque to the steering wheel; and

an applied friction torque changing unit which changes the applied friction torque based on the transmission ratio.

2. The power steering device according to claim 1, wherein the applied friction torque changing unit changes a rise-up characteristic of the applied friction torque based on the transmission ratio.

3. The power steering device according to claim 2, wherein the applied friction torque changing unit slows down a rise-up of the applied friction torque when a rotation of a steering shaft accelerates.

4. The power steering device according to claim 1, wherein the applied friction torque changing unit changes a maximum value of the applied friction torque based on the transmission ratio.