Suspension control system

• US 5,442,554 A
• Filed: 09/03/1992
• Issued: 08/15/1995
• Est. Priority Date: 09/11/1991
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Ohtagaki, Shigeki
• Primary Examiner(s): Chin, Gary
• Application Number:
  US07/940,353
• Time in Patent Office: 1,076 Days
• Field of Search: 364/424.05, 280/707, 280/840
• US Class Current: 701/37
• CPC Class Codes: B60G 17/018 characterised by the use of a specific signal treatment or control method
• CPC Class Codes: B60G 2400/10 Acceleration; Deceleration
• CPC Class Codes: B60G 2400/102 vertical
• CPC Class Codes: B60G 2400/204 Vehicle speed
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2400/33 Throttle position
• CPC Class Codes: B60G 2400/412 of steering wheel or column
• CPC Class Codes: B60G 2500/102 stepwise
• CPC Class Codes: B60G 2600/28 Temporary fluctuations
• CPC Class Codes: B60G 2800/22 Braking, stopping
• CPC Class Codes: F21W 2102/30 Fog lights

Abstract

A suspension control system includes: a vehicle speed sensor for providing a signal representing a vehicle speed, a vehicle body behavior variation detecting device for detecting variations in behavior of a vehicle body, and a vehicle speed deciding device for calculating a vehicle speed from the signal provided by the vehicle speed sensor to compare the vehicle speed with a predetermined vehicle speed. The control system further includes a vehicle body behavior variation counter for counting vehicle body behavior variations for a predetermined period of time according to an output of the vehicle body behavior variation detecting device, a damping force changing device for changing a vehicle body suspension damping force at least in three steps and a damping force determining device for determining a damping force according to the vehicle speed decided by the vehicle speed deciding device and the number of vehicle body behavior variations counted by the vehicle body behavior variation counter, to apply an instruction signal to the damping force changing device, so that, when the vehicle speed decided by the vehicle speed deciding device is equal to or higher than a first predetermined vehicle speed, and when the number of vehicle body behavior variations counted by the vehicle body behavior variation counter is equal to or higher than a first predetermined value, the damping force changing device operates to increase the damping force to an increased value and to maintain the damping force at the increased value.

Claims

1. A suspension control system for use in a vehicle, comprising:

a vehicle speed sensor for sensing a vehicle speed to provide a signal representing said vehicle speed;

vehicle body behavior variation detecting means for detecting variations in a steering angular speed which indicates whether said vehicle is abruptly turned;

vehicle speed determining means for calculating a vehicle speed from said signals provided by said vehicle speed sensor and comparing said calculated vehicle speed with a value representing a predetermined vehicle speed;

vehicle body behavior variation counting means for counting said variations in the steering angular speed for a predetermined period of time according to an output of said vehicle body behavior variation detecting means;

damping force changing means for changing a vehicle body suspension damping force; and

damping force determining means for determining a damping force according to said vehicle speed determined by said vehicle speed determining means and the number of variations in the steering angular speed counted by said vehicle body behavior variation counting means, to apply an instruction signal to said damping force changing means, so that, when said vehicle speed determined by said vehicle speed determining means is equal to or higher than a first predetermined vehicle speed, and when the number of said variations in the steering angular speed counted by said vehicle body behavior variation counting means is equal to or higher than a first predetermined value, said damping force changing means operates to increase said damping force to an increased value and to maintain said damping force at said increased value.

2. A suspension control system as claimed in claim 1, wherein when said vehicle speed is lower than a second predetermined vehicle speed which is lower than said first predetermined vehicle speed, said damping force determining means operates to switch a damping force held at said increased value, which is a relatively high value, back to a value lower than said increased value.

3. A suspension control system as claimed in claim 1, wherein when said damping force is held at said increased value, which is a relatively high value, and none of said variations in the steering angular speed occurs for the predetermined period of time, said damping force determining means operates to switch a current damping force back to a value lower than said increased value.

4. A suspension control system for use in a vehicle, comprising;

a vehicle speed sensor for sensing a vehicle speed to provide a signal representing said vehicle speed;

vehicle body behavior variation detecting means for detecting variations in a braking condition which indicates whether said vehicle is abruptly braked;

vehicle speed determining means for calculating a vehicle speed from said signals provided by said vehicle speed sensor and comparing said calculated vehicle speed with a value representing a predetermined vehicle speed;

vehicle body behavior variation counting means for counting said variations in the braking condition for a predetermined period of time according to an output of said vehicle body behavior variation detecting means;

damping force changing means for changing a vehicle body suspension damping force; and

damping force determining means for determining a damping force according to said vehicle speed determined by said vehicle speed determining means and the number of variations in the braking condition counted by said vehicle body behavior variation counting means, to apply an instruction signal to said damping force changing means so that when said vehicle speed determined by said vehicle speed determining means is equal to or higher than a first predetermined vehicle speed, and when the number of said variations in the braking condition counted by said vehicle body behavior variation counting means is equal to or higher than a first predetermined value, said damping force changing means operates to increase said damping force to an increased value and to maintain said damping force at said increased value.

5. A suspension control system as claimed in claim 4, wherein when said vehicle speed is lower than a second predetermined vehicle speed which is lower than said first predetermined vehicle speed, said damping force determining means operates to switch a damping force held at said increased value, which is a relatively high value, back to a value lower than said increased value.

6. A suspension control system as claimed in claim 4, wherein when said damping force is held at said increased value, which is a relatively high value, and none of said variations in the braking condition occurs for the predetermined period of time, and damping force determining means operates to switch a current damping force back to a value lower than said increased value.

7. A suspension control system for use in a vehicle, comprising:

a vehicle speed sensor for sensing a vehicle speed to provide a signal representing said vehicle speed;

vehicle body behavior variation detecting means for detecting variations in behavior of a vehicle body;

vehicle speed determining means for calculating a vehicle speed from said signal provided by said vehicle speed sensor and comparing said calculated vehicle speed with a value representing a predetermined vehicle speed;

vehicle body behavior variation counting means for counting said vehicle body behavior variations for a predetermined period of time according to an output of said vehicle body behavior variation detecting means;

damping force changing means for changing a vehicle body suspension damping force; and

damping force determining means for determining a damping force according to said vehicle speed determined by said vehicle speed determining means and the number of vehicle body behavior variations counted by said vehicle body behavior variation counting means, to control said damping force changing means in the following manner;

when the vehicle speed determined by said vehicle speed determining means is lower than a first predetermined vehicle speed, and said damping force is set to a low value, said damping force changing means operates to maintain said damping force at said low value regardless of whether any said vehicle body behavior variation has occurred during the predetermined period of time;

when said vehicle speed determined by said vehicle speed determining means is equal to or higher than said first predetermined vehicle speed, said damping force is set to a low value, and the number of said vehicle body behavior variations counted by said vehicle body behavior variation counting means during the predetermined period of time is equal to or higher than a first predetermined value, said damping force changing means operates to increase said damping force to an increased value and to maintain said damping force at said increased value;

when said damping force is set to a high value, and said vehicle speed detected by said vehicle speed determining means is lower than a second predetermined vehicle speed, said damping force changing means operates to return said damping force to said low value; and

when said damping force is set to a high value, and said vehicle speed detected by said vehicle speed determining means is equal to or higher than said second predetermined vehicle speed, said damping force changing means operates to maintain said damping force at said high value if said damping force has not been at said high value for a determined period of time.

8. A suspension control system as claimed in claim 7, wherein said damping force determining means further controls said damping force changing means so that when said damping force is set to a high value, and said vehicle speed detected by said vehicle speed determining means is equal to or higher than said second predetermined vehicle speed, said damping force changing means operates to maintain said damping force at said high value if said damping force has been at said high value for said determined period of time and the number of said vehicle body behavior variations counted by said vehicle body behavior variation counting means is equal to or higher than a second predetermined value.

9. A suspension control system as claimed in claim 7, wherein said damping force determining means further controls said damping force changing means so that when said damping force is set to a high value, and said vehicle speed detected by said vehicle speed determining means is equal to or higher than said second predetermined vehicle speed, said damping force changing means operates to return said damping force to said low value if said damping force has been at said high value for said determined period of time and the number of said vehicle body behavior variations counted by said vehicle body behavior variation counting means is less than a second predetermined value.

10. A suspension control system as claimed in claim 7, wherein said damping force determining means further controls said damping force changing means so that when said vehicle speed detected by said vehicle speed determining means is equal to or higher than said first predetermined vehicle speed, said damping force is set to said low value, and the number of said vehicle body behavior variations counted by said vehicle body behavior variation counting means is lower than said first predetermined value, said damping force changing means operates to keep said damping force at said low value.

11. A suspension control system as claimed in claim 8, wherein said damping force determining means further controls said damping force changing means so that:

when said damping force is set to a high value, and said vehicle speed detected by said vehicle speed determining means is equal to or higher than said second predetermined vehicle speed, said damping force changing means operates to return said damping force to said low value if said damping force has been at said high value for said determined period of time and the number of said vehicle body behavior variations counted by said vehicle body behavior variation counting means is less than said second predetermined value; and

when said vehicle speed detected by said vehicle speed determining means is equal to or higher than said first predetermined vehicle speed, said damping force is set to said low value, and the number of said vehicle body behavior variations counted by said vehicle body behavior variation counting means is lower than said first predetermined value, said damping force changing means operates to keep said damping force at said low value.

12. A suspension control system as claimed in claim 7, wherein the behavior of said vehicle body detected by said vehicle body behavior variation detecting means is a steering angular speed which indicates whether said vehicle is abruptly turned.

13. A suspension control system as claimed in claim 11, wherein the behavior of said vehicle body detected by said vehicle body behavior variation detecting means is a steering angular speed which indicates whether said vehicle is abruptly turned.

14. A suspension control system as claimed in claim 7, wherein the behavior of said vehicle body detected by said vehicle body behavior variation detecting means is a braking condition which indicates whether said vehicle is abruptly braked.

15. A suspension control system as claimed in claim 11, wherein the behavior of said vehicle body detected by said vehicle body behavior variation detecting means is a braking condition which indicates whether said vehicle is abruptly braked.