Steering system of vehicle

Patent metadata

Field	Value
Publication number	US-11479294-B2
Application number	US-201916448400-A
Country	US
Kind code	B2
Filing date	Jun 21, 2019
Priority date	Dec 7, 2018
Publication date	Oct 25, 2022
Grant date	Oct 25, 2022

Abstract

A steering system of a vehicle is provided. The steering system adjusts the torsional rigidity of a torsion bar without limitation as to the configuration thereof and performs active control responding to the vehicle state by adjusting steering characteristics by controlling the torsional rigidity of the torsion bar based on the traveling condition, load state or driving mode of the vehicle. The steering system includes an MR assist device, which is coupled to an end portion of the torsion bar and adjusts the rotation and torsional rigidity of the torsion bar using an MR fluid as a working fluid.

First claim

What is claimed is:

1. A steering system of a vehicle, comprising:
a steering gear box configured to multiply steering force applied by a driver and to output the multiplied steering force by generating steering assist force using oil pressure,
wherein the steering gear box comprises:
an input shaft inserted into and coupled to a housing, the input shaft being configured to receive the steering force applied by the driver;
a worm shaft installed in the housing, the worm shaft being rotatably supported by the housing;
a cylinder into which the worm shaft is inserted and to which the worm shaft is screw-coupled, the cylinder moving forwards and backwards in an axial direction within the housing when the worm shaft rotates;
a torsion bar interposed between the input shaft and the worm shaft to transmit rotational force of the input shaft to the worm shaft;
a valve assembly configured to selectively apply or remove oil pressure to or from the housing to generate steering assist force;
a sector shaft coupled to the cylinder, the sector shaft being configured to output steering force, to which the steering assist force is added, by being rotated by forward and backward movement of the cylinder; and
a magneto-rheological (MR) assist device coupled to an end portion of the torsion bar, the MR assist device being configured to adjust rotation and torsional rigidity of the torsion bar using an MR fluid as a working fluid.

2. The steering system of claim 1 , wherein the MR assist device includes:
an MR fluid chamber installed to an end portion of the housing, wherein the end portion of the torsion bar is inserted into the MR fluid chamber and wherein the MR fluid chamber is filled with the MR fluid and sealed;
a blade coupled to the end portion of the torsion bar, the blade being rotatable together with the torsion bar and including a plurality of wings;
at least one electromagnet assembly mounted to at least one of the wings, the electromagnet assembly including an orifice to allow the MR fluid to pass therethrough; and
a controller configured to adjust current to be applied to the electromagnet assembly.

3. The steering system of claim 2 , wherein the at least one electromagnet assembly includes a plurality of electromagnet assemblies, each of the electromagnet assemblies being mounted to a respective one of the wings of the blade and including the orifice, and wherein installation positions of the electromagnet assemblies in the wings are same.

4. The steering system of claim 2 , wherein the electromagnet assembly includes:
an outer shell inserted into an installation aperture formed in a corresponding one of the wings, the outer shell having a ring shape;
a coil unit inserted into the outer shell, the coil unit having a ring shape; and
an orifice tube fixed to an inner surface of the coil unit,
wherein an internal space in the orifice tube is formed as an orifice through which the MR fluid passes.

5. The steering system of claim 2 , wherein a cable for applying current to the electromagnet assembly passes through a lower-surface aperture formed in the MR fluid chamber and is connected to the electromagnet assembly via the blade within the MR fluid chamber, and wherein an MR fluid seal is interposed between the cable and the lower-surface aperture formed in the MR fluid chamber.

6. The steering system of claim 2 , wherein the controller is configured to determine a traveling condition of a vehicle from current vehicle state information collected from the vehicle and apply a current value that corresponds to the determined traveling condition of the vehicle to the electromagnet assembly.

7. The steering system of claim 6 , wherein the vehicle state information includes a current vehicle speed detected by a vehicle speed sensor, and wherein the controller is configured to determine that the traveling condition of the vehicle is one of high-speed travel, in which the current vehicle speed is equal to or greater than a predetermined speed, and low-speed travel, in which the current vehicle speed is less than the predetermined speed, and is configured to apply a current value that corresponds to the determined traveling condition of the vehicle to the electromagnet assembly.

8. The steering system of claim 6 , wherein the vehicle state information includes a steering angle detected by a steering angle sensor, and wherein the controller is configured to determine that the traveling condition of the vehicle is one of turning travel, in which the steering angle is equal to or greater than a predetermined angle, and straight travel, in which the steering angle is less than the predetermined angle, and is configured to adjust a current value that corresponds to the determined traveling condition of the vehicle to the electromagnet assembly.

9. The steering system of claim 6 , wherein the vehicle state information includes a current vehicle speed detected by a vehicle speed sensor and a steering angle detected by a steering angle sensor.

10. The steering system of claim 9 , wherein the vehicle state information further includes an air pressure of tires detected by a tire pressure sensor.

11. The steering system of claim 9 , wherein the controller is configured to determine that the traveling condition of the vehicle is one of low-speed turning travel, in which the current vehicle speed is less than a predetermined speed and the steering angle is equal to or greater than a predetermined angle, low-speed straight travel, in which the current vehicle speed is less than the predetermined speed and the steering angle is less than the predetermined angle, high-speed turning travel, in which the current vehicle speed is equal to or greater than the predetermined speed and the steering angle is equal to or greater than the predetermined angle, and high-speed straight travel, in which the current vehicle speed is equal to or greater than the predetermined speed and the steering angle is less than the predetermined angle, and configured to adjust a current value that corresponds to the determined traveling condition of the vehicle to the electromagnet assembly.

12. The steering system of claim 11 , wherein the controller is configured to determine a current value that corresponds to the determined traveling condition of the vehicle by multiplying a predetermined normal current by a correction coefficient corresponding to a determined one of the low-speed turning travel, the low-speed straight travel, the high-speed turning travel and the high-speed straight travel.

13. The steering system of claim 12 , wherein the correction coefficient is set to be a larger value in the low-speed straight travel than in the low-speed turning travel and is set to be a larger value in the high-speed straight travel than in the high-speed turning travel.

14. The steering system of claim 12 , wherein the correction coefficient is set to be a larger value in the low-speed straight travel than in the high-speed turning travel, is set to be a larger value in the high-speed straight travel than in the low-speed straight travel, and is set to be a larger value in the high-speed straight travel than in the low-speed turning travel.

15. The steering system of claim 11 , wherein the vehicle state information further includes an air pressure of tires detected by a tire pressure sensor, and wherein the controller is configured to adjust a current value, calculated by multiplying the current value corresponding to the determined one of the low-speed turning travel, the low-speed straight travel, the high-speed turning travel and the high-speed straight travel by a cor

Assignees

• Hyundai Motor Co Ltd
• Kia Motors Corp

Inventors

• Lee Ji Hoon
• Suh Jin Gyo
• Cho Sung Han
• Lee Seo An

Classifications

• B62D5/18 Primary

  characterised by power transmitting means · CPC title

• B62D6/007

  adjustable by the driver, e.g. sport mode · CPC title

• F16F2224/045

  magnetorheological · CPC title

• B62D5/08

  characterised by type of {steering} valve used (valves in general F16K) · CPC title

• F16F9/537

  specially adapted valves therefor · CPC title