Power steering apparatus for a vehicle with yaw control

• US 5,078,226 A
• Filed: 06/14/1990
• Issued: 01/07/1992
• Est. Priority Date: 06/15/1989
• Status: Expired due to Fees

• Current Assignee: Nippon Soken, Inc. (DENSO Corporation)
• Original Assignee: Nippon Soken, Inc. (DENSO Corporation)
• Inventors: Iwanami, Shigeki, Inagaki, Mitsuo, Sasaya, Hideaki
• Primary Examiner(s): Rice, Kenneth R.
• Assistant Examiner(s): DICKSON, PAUL N
• Application Number:
  US07/537,943
• Time in Patent Office: 572 Days
• Field of Search: 180/143, 180/132, 180/79.1, 180/141, 180/142, 364/424.05
• US Class Current: 180/422
• CPC Class Codes: B62D 6/00 Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits means for initiating a change in direction B62D1/00; steering valves B62D5/06; combined with means for inclining the vehicle body or wheels on bends B62D9/00
• CPC Class Codes: B62D 6/04 responsive only to forces disturbing the intended course of the vehicle, e.g. forces acting transversely to the direction of vehicle travel

Abstract

A power steering apparatus for a vehicle having a hydraulic mechanism for generating a force applied to a steering mechanism for reducing a force needed to operate a steering member (wheel). A device is provided for determining a condition wherein a yaw rate generated in the vehicle does not match a steering operation of the steering member. A hydraulic or electric torque motor is operated for generating a counter steering force applied to the steering mechanism, to cancel the yaw rate which does not match the operation of the steering member.

Claims

1. A power steering system for a vehicle having wheels to be steered, comprising:

a steering member;

a steering mechanism for connecting the steering member with said wheels to be steered so that said wheels are steered in accordance with a movement of the steering member;

means for generating an assisting force in the steering mechanism for reducing an effort which is necessary for moving the steering member when carrying out a steering operation;

means for detecting a vehicle speed;

means for detecting a condition of the steering member during an operation thereof;

means for detecting an actual yaw rate of the vehicle;

means for detecting whether said actual yaw rate matches a degree of an operation of the steering member, while taking at least the vehicle speed into consideration; and

means for generating, only when it is determined that the actual yaw rate does not match a degree of operation of the steering member, a counter steering force to be applied to the steering mechanism in a direction corresponding to a situation of the vehicle which has caused the determined difference between degree of operation and actual yaw rate, thereby alerting a driver to drive the vehicle safely in accordance with said situation.

2. A power steering system according to claim 1, wherein it further comprises means for determining if the detected vehicle speed is higher than a predetermined value, and said generating means generates the steering reaction force only if it is determined that the vehicle speed is higher than the predetermined value.

3. A power steering system according to claim 1, wherein said generating means comprise means connected to the steering mechanism for driving the steering mechanism in a desired steering direction, means for calculating a desired degree of the steering reaction force to be generated for cancelling a yaw rate which does not match the steering operation of the steering member, and means for operating the drive means to obtain the calculated steering reaction force.

5. A power system according to claim 3, wherein said drive means comprises an electrical motor connected to the steering mechanism, means for controlling a direction of an electric signal as applied to the electric motor, and means for controlling a degree of strength of the electric signal for obtaining a desired steering reaction force.

4. A power steering system for a vehicle having wheels to be steered, comprising:

a steering member;

a steering mechanism for connecting the steering member with said wheels to be steered so that said wheels are steered in accordance with a movement of the steering member;

means for generating an assisting force in the steering mechanism for reducing an effort which is necessary for moving the steering member when carrying out a steering operation;

means for detecting a vehicle speed;

means for detecting a condition of the steering member during an operation thereof;

means for detecting an actual yaw rate of the vehicle;

means for determining whether said actual yaw rate matches a degree of an operation of the steering member, while taking at least the vehicle speed into consideration;

means for generating a steering reaction force to be applied to the steering member to thereby cancel a yaw rate which does not match a degree of operation of the steering member; and

means for determining if the detected vehicle speed is higher than a predetermined value, and said generating means generates the steering reaction force only when the vehicle speed is higher than the predetermined value;

wherein said drive means comprises a hydraulic motor connected to the steering mechanism, a hydraulic system connected to the hydraulic motor for obtaining a rotational movement of the steering mechanism in a desired steering direction, first valve means for controlling a direction of flow of an operating liquid to the hydraulic motor, and second valve means for controlling an amount of fluid supplied to the hydraulic motor for obtaining a desired steering reaction force.

6. A power steering system for a vehicle having wheels to be steered, comprising:

a steering member;

a steering mechanism for connecting the steering member with said wheels to be steered so that said wheels are steered in accordance with a movement of the steering member;

means for generating an assisting force in the steering mechanism for reducing an effort necessary to move the steering member when carrying out a steering operation;

means for detecting a condition of the steering member when operated;

means for detecting an actual yaw rate of the vehicle;

means responding to a signal detected by the steering condition detecting means for determining if the steering member is operated more than a predetermined steering value;

means responsive to a signal from the yaw rate detecting means for determining if the actual yaw rate is larger than a predetermined yaw value;

means for generating, only upon a determination that a steering operation more than the predetermined steering value is carried out by the steering operation detecting means and that the yaw rate as detected by the yaw rate detecting means is smaller than the predetermined yaw value, a counter steering force to be applied to the steering mechanism in a direction corresponding to a situation of the vehicle which has caused said determination, thereby alerting a driver to drive the vehicle safely in accordance with said situation.

7. A steering system according to claim 6, further comprising means for allowing an intermittent transmission of the counter steering force to the steering mechanism upon the determination of the steering operation and when the yaw rate is not detected.

8. A power system for a vehicle having wheels to be steered, comprising:

a steering member;

a steering mechanism for connecting the steering member with said wheels to be steered so that said wheels are steered in accordance with a movement of the steering member;

means for generating an assisting force in the steering mechanism for reducing an effort necessary to move the steering member when carrying out a steering operation;

means for detecting a condition of the steering member when operated;

means for detecting an actual yaw rate of the vehicle;

means responding to a signal detected by the steering detecting means for determining if the steering member is operated more than a predetermined steering value;

means responsive to a signal from the yaw rate detecting means for determining if the yaw rate as detected is larger than a predetermined value;

means for generating, only upon a determination that a steering operation more than the predetermined steering value is not carried out by the steering operation detecting means and that the actual yaw rate as detected by the yaw rate detecting means is larger than the predetermined value, a counter steering force to be applied to the steering mechanism in such a manner that the turning movement otherwise generated in the vehicle by the yaw rate is cancelled.

9. A power steering system according to claim 8, further comprising means for allowing a continuous transmission of the generated counter steering force upon a determination that the steering operation is not carried out and determination of a yaw rate.

10. A power steering system for a vehicle having wheels to be steered, comprising:

a steering member;

a steering mechanism for connecting the steering member with said wheels to be steered so that said wheels are steered in accordance with a movement of the steering member;

means for generating an assisting force in the steering mechanism for reducing an effort necessary moving the steering member when carrying out a steering operation;

means for detecting a condition of the steering member when operated;

means for detecting a yaw rate of the vehicle;

means, responding to a signal detected by the steering condition detection means and yaw rate detection means, for calculating a rate of change of the value of the yaw rate to the change in the angle of the steering member when operated;

means, upon a determination of a decrease in said rate of change of value of the yaw rate calculated by said calculating means, for generating a counter steering force to be applied to the steering mechanism in a direction opposite to the direction of the operation of the steering by the assisting force generation means; and

means for allowing a continuous transmission of the counter steering force to the steering mechanism upon the determination of decrease in the yaw rate while the degree of the steering operation is increased.

11. A power system for a vehicle having wheels to be steered, comprising:

a steering member;

a steering mechanism for connecting the steering member with said wheels to be steered so that said wheels are steered in accordance with a movement of the steering member;

means for generating an assisting force in the steering mechanism for reducing an effort necessary to move the steering member when carrying out the steering operation;

means for detecting a condition of the steering member when operated;

means for detecting a yaw rate of the vehicle;

means, responding to a signal detected by the steering condition detection means and yaw rate detection means, for calculating a rate of change of the value of the yaw rate to the change in the angle of the steering member when operated;

means for calculating a ratio of the yaw rate to the steering angle;

means for determining, from the ratio of the yaw rate to the steering angle, a condition wherein an increase of the rate of the change in the yaw rate is decreased with respect to the increase in the degree of the operation of the steering member for generating a counter steering force to be applied to the steering mechanism in as direction opposite to the direction of the operation of the steering by the assisting force generation means; and

means for allowing an intermittent transmission of the counter steering force to the steering mechanism upon a determination of a condition where the increase of the rate of the change in the yaw rate is decreased with respect to the increase in the degree of the operation of the steering member.

12. A power system for a vehicle having wheels to be steered, comprising:

a steering member;

a steering mechanism for connecting the steering member with said wheels to be steered so that said wheels are steered in accordance with a movement of the steering member;

means for generating an assisting force in the steering mechanism for reducing an effort necessary to move the steering member when carrying out steering operation;

means for detecting a condition of the steering member when operated;

means for detecting a yaw rate of the vehicle;

means, responding to a signal detected by the steering condition detection means and yaw rate detection means, for calculating a rate of change of the value of the yaw rate to the change in the angle of the steering member when operated;

means, upon determination of a decrease in said rate of change value of the yaw rate calculated by said calculating means, for generating a counter steering force to be applied to the steering mechanism in a direction opposite to the direction of the operation of the steering by the assisting force generation means.

13. A power system for a vehicle having wheels to be steered, comprising:

a steering member;

a steering mechanism for connecting the steering member with said wheels to be steered so that said wheels are steered in accordance with a movement of the steering member;

means for generating an assisting force in the steering mechanism for reducing an effort necessary to move the steering member when carrying out the steering operation;

means for detecting a condition of the steering member when operated;

means for detecting a yaw rate of the vehicle;

means, responding to a signal detected by the steering condition detection means and yaw rate detection means, for calculating a rate of change of the value of the yaw rate to the change in the angle of the steering member when operated;

means for calculating a ratio of the yaw rate to the steering angle;

means for determining, from the ratio of the degree of change of the yaw rate to the change in the angle of the steering member and a ratio of the yaw rate to the steering angle, a condition wherein an increase of the rate of the change in the yaw rate is decreased with respect to the increase in the degree of the operation of the steering member for generating a counter steering force to be applied to the steering mechanism in a direction opposite to the direction of the operation of the steering by the assisting force generation means.