Steering system for vehicle

Patent metadata

Field	Value
Publication number	US-2024253697-A1
Application number	US-202218564342-A
Country	US
Kind code	A1
Filing date	Jul 19, 2022
Priority date	Jul 20, 2021
Publication date	Aug 1, 2024
Grant date	—

Abstract

Provided is a steering system for a vehicle that can accurately determine a degradation level of a steering actuator according to a traveling state of the vehicle. The steering system for the vehicle includes; a steering mechanism configured to steer wheels; a steering actuator configured to apply a driving force to the steering mechanism; and a controller configured to control the steering actuator. The steering mechanism includes a rack shaft that is movable in a vehicle width direction from a prescribed reference position. The controller is configured to calculate an evaluation value according to a use state of the steering actuator and to determine a degradation level of the steering actuator by comparing the evaluation value with at least one threshold that is set based on a moving amount of the rack shaft from the reference position and a vehicle speed.

First claim

What is claimed is:

1 . A steering system for a vehicle, comprising:
a steering mechanism configured to steer wheels; a steering actuator configured to apply a driving force to the steering mechanism; and a controller configured to control the steering actuator, wherein the steering mechanism includes a rack shaft that is movable in a vehicle width direction from a prescribed reference position, and the controller is configured to calculate an evaluation value according to a use state of the steering actuator and to determine a degradation level of the steering actuator by comparing the evaluation value with at least one threshold that is set based on a moving amount of the rack shaft from the reference position and a vehicle speed.

2 . The steering system for the vehicle according to claim 1 , wherein the at least one threshold comprises a plurality of thresholds, and
the controller is configured to determine the degradation level of the steering actuator by comparing the evaluation value with the plurality of thresholds.

3 . The steering system for the vehicle according to claim 1 , wherein the controller is configured to regularly determine the degradation level of the steering actuator and to output a signal indicating that the degradation level of the steering actuator is equal to or higher than a prescribed level only if determination that the degradation level of the steering actuator is equal to or higher than the prescribed level is made in succession for a prescribed period or more or for a prescribed number of times or more.

4 . The steering system for the vehicle according to claim 1 , wherein the controller is configured to determine the degradation level of the steering actuator higher in a case where the evaluation value is higher than the threshold than in a case where the evaluation value is equal to or lower than the threshold, and
in a case where the vehicle speed is lower than a prescribed reference speed, the threshold is set to become higher as the moving amount of the rack shaft from the reference position increases.

5 . The steering system for the vehicle according to claim 4 , wherein in a case where the vehicle speed is equal to or higher than the reference speed, the threshold is set to a constant value regardless of the moving amount of the rack shaft from the reference position.

6 . The steering system for the vehicle according to claim 1 , wherein in a case where a moving speed of the rack shaft is equal to or more than a prescribed determination suspension speed, the controller suspends a determination of the degradation level of the steering actuator.

7 . The steering system for the vehicle according to claim 1 , wherein the controller is configured to determine the degradation level of the steering actuator higher in a case where the evaluation value is higher than the threshold than in a case where the evaluation value is equal to or lower than the threshold, and
the evaluation value is set to become higher as a value of an electric current that flows according to drive of the steering actuator increases.

8 . The steering system for the vehicle according to claim 1 , further comprising a temperature sensor configured to detect a temperature of the steering actuator or the controller,
wherein the controller is configured to determine the degradation level of the steering actuator higher in a case where the evaluation value is higher than the threshold than in a case where the evaluation value is equal to or lower than the threshold, and in a case where the temperature detected by the temperature sensor is higher than a prescribed reference temperature, the evaluation value is set to become higher as the temperature detected by the temperature sensor becomes higher.

9 . The steering system for the vehicle according to claim 1 , further comprising a battery configured to supply electric power to the steering actuator,
wherein the controller is configured to determine the degradation level of the steering actuator higher in a case where the evaluation value is higher than the threshold than in a case where the evaluation value is equal to or lower than the threshold, and in a case where a voltage of the battery is lower than a prescribed reference voltage, the evaluation value is set to become higher as the voltage of the battery becomes lower.

10 . The steering system for the vehicle according to claim 1 , wherein the evaluation value is determined using a torque utilization value, and
the torque utilization value is calculated based on outputted torque of the steering actuator.

11 . The steering system for the vehicle according to claim 1 , further comprising a steering member configured to receive a steering operation,
wherein the steering mechanism is mechanically separated from the steering member.

Assignees

• Honda Motor Co Ltd
• Thyssenkrupp Presta Ag

Inventors

• Ojima Yosuke
• Hanji Munetsugu
• Yamaguchi Takaya
• MIKLOS Aranyi
• Imre Szepessy
• MATE Kocsor
• MARIA Beko
• Andras Toth
• BENCE Bodnar
• JENO Gyokeres

Classifications

• B62D5/0481 Primary

  monitoring the steering system, e.g. failures · CPC title