Control system for an active suspension system in a motor vehicle and method for controlling motor vehicle handling around curves

• US 5,481,459 A
• Filed: 10/31/1994
• Issued: 01/02/1996
• Est. Priority Date: 11/05/1993
• Status: Expired due to Fees

• Current Assignee: Fichtel & Sachs AG (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: Fichtel & Sachs AG (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Bungeler, Jorg
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): NGUYEN, TAN QUANG
• Application Number:
  US08/331,894
• Time in Patent Office: 428 Days
• Field of Search: 364/424.05, 364/426.02, 364/426.03, 364/426.04, 364/492, 364/565, 364/570, 364/571.01, 280/772, 280/688, 280/707, 280/714, 280/840, 180/170, 180/197, 180/143, 324/160, 324/161, 324/162
• US Class Current: 701/37
• CPC Class Codes: B60G 17/0162 mainly during a motion involving steering operation, e.g. cornering, overtaking B60G17/0164 takes precedence
• CPC Class Codes: B60G 2202/413 Hydraulic actuator
• CPC Class Codes: B60G 2400/104 lateral or transversal with regard to vehicle
• CPC Class Codes: B60G 2400/204 Vehicle speed
• CPC Class Codes: B60G 2400/25 Stroke; Height; Displacement
• CPC Class Codes: B60G 2400/41 Steering angle
• CPC Class Codes: B60G 2800/24 Steering, cornering
• CPC Class Codes: G01P 1/10 for indicating predetermined speeds
• CPC Class Codes: G01P 15/0891 with indication of predetermined acceleration values G01P15/135 takes precedence

Abstract

An active hydraulic system for a motor vehicle, which active hydraulic system comprises a supply pump, a number of valves to control the actuators, and a measuring device to determine the movement parameters of the vehicle. The components of the active hydraulic system follow a process for the recognition of cornering for a vehicle. To achieve this, the components of the active hydraulic system measure signals and accordingly adjust and alter the ride of the vehicle. The process includes measuring a vehicle acceleration signal a and comparing the vehicle acceleration signal a to an acceleration threshold value a_s. A vehicle velocity signal v is then compared to a lower vehicle velocity threshold value v_u. The process further includes comparing the vehicle velocity signal v to an upper vehicle velocity threshold value v_o. A steering movement which is measured as a value of s_delta, is detected as a steering angle below and above a steering angle threshold value s_delta. When the velocity of the vehicle is between the lower and upper vehicle velocity threshold values v_u and v_o, respectively, the power supply of the actuators is then actuated only if the actual acceleration simultaneously increases above the acceleration threshold value a_s.

Claims

1. A suspension system assembly comprising:

at least one shock absorber, said at least one shock absorber comprising;

a sealed cylinder defining a chamber therein, said cylinder containing a damping fluid;

said cylinder having a first end and a second end;

a piston rod sealingly projecting into said cylinder and being axially displaceable with respect to said cylinder;

said first end of said cylinder being disposed at said piston rod;

a piston being attached to said piston rod, said piston being slidably disposed within said cylinder to sealingly divide said chamber into first and second chambers;

means for permitting flow of damping fluid between said first and second chambers;

said cylinder having an inner wall disposed towards said piston rod and an outer wall disposed radially away from said piston rod;

a central longitudinal axis defined through said sealed cylinder, the central longitudinal axis defining a longitudinal direction of said shock absorber;

means for the recognition of cornering for a vehicle with an active hydraulic system;

said means for the recognition of cornering for a vehicle with an active hydraulic system comprising a supply pump for the hydraulic system, a plurality of actuators, a number of valves for control of the actuators and a measuring device for determination of vehicle movement parameters;

said means for the recognition of cornering for a vehicle with an active hydraulic system further comprising;

means for measuring a vehicle acceleration signal "a";

means for providing an acceleration threshold value "a_s ";

means for comparing said vehicle acceleration signal "a" to said acceleration threshold value "a_s ";

means for measuring a vehicle velocity signal "v";

means for providing a lower vehicle velocity threshold value "v_u ";

means for comparing said vehicle velocity signal "v" to a lower vehicle velocity threshold value "v_u ";

means for providing an upper vehicle velocity threshold value "v_o "

means for comparing said vehicle velocity signal "v" to said upper vehicle velocity threshold value "v_o ";

means for providing a steering angle threshold value "s_delta ";

means for detecting a steering movement as a steering angle;

said means for detecting a steering movement as a steering angle comprising means for detecting said steering angle below and above said steering angle threshold value "s_delta ";

means for actuating power to the suspension system;

said means for actuating power to the suspension system comprising means for providing a signal to said valves for control of the actuators;

said means for providing a signal to said valves for control of the actuators comprising means for providing a signal to said valves at a vehicle velocity in the vehicle velocity range between the vehicle velocity threshold values "v_u " and "v_o ";

said means for providing a signal to said valves at a vehicle velocity in the vehicle velocity range between the vehicle velocity threshold values "v_u " and "v_o " comprising means for providing a signal to said valves only if the actual measured acceleration "a" increases above the acceleration threshold value "a_s " at the same time as the vehicle velocity is in the vehicle velocity range between the vehicle velocity threshold values "v_u " and "v_o ";

a spring for applying a substantially longitudinally directed force with said shock absorber;

said spring being operatively connected to apply the force to said shock absorber.

2. Apparatus according to claim 1, wherein:

said means for the recognition of cornering comprises;

means for comparing said vehicle velocity signal "v" to said upper vehicle velocity threshold "v_o ";

said means for comparing said vehicle velocity signal "v" to said upper vehicle velocity threshold "v_o " comprises means for determining when said vehicle velocity signal "v" is greater than "v_o ";

means for determining a steering angle of the vehicle,

means for providing a signal for actuating power to the suspension system relating to the vehicle acceleration signal "a" without consideration of the steering angle threshold value "s_delta ".

3. Apparatus according to claim 2 wherein:

means for providing a yet lower vehicle acceleration threshold value "a_h ";

said yet lower vehicle acceleration threshold value a_h being an acceleration less than said vehicle acceleration value "a_s ";

means for deactivating the actuators;

said means for deactivating the actuators comprising;

means for sensing the previous vehicle speed signal "v" being above "v_o " and for sensing the actual value of vehicle acceleration being below the yet lower vehicle acceleration threshold value "a_h "; and

means for deactivating the actuators upon said sensing means sensing the previous vehicle speed signal "v" as being above "v" and the actual value of vehicle acceleration as being below the yet lower vehicle acceleration threshold value "a_h ".

4. Apparatus according to claim 1 including:

means for providing a yet lower vehicle acceleration threshold value "a_h ";

said yet lower vehicle acceleration threshold value "a_h " being smaller than the vehicle acceleration threshold value "a_s ";

means for determining when the acceleration "a" is below the yet lower vehicle acceleration threshold value "a_h " and the steering angle is below the steering angle threshold value "s_delta ";

means for actuating the actuators upon said determining means determining that the acceleration "a" is below the yet lower vehicle acceleration threshold value "a_h " and the steering angle is below the steering angle threshold value "s_delta ";

said means for determining indicating a signal that both the steering angle is below the steering angle threshold value and the vehicle acceleration value is below the yet lower vehicle acceleration threshold value "a_h " upon the instantaneous vehicle velocity signal "v" being below the lower vehicle velocity threshold value "v_u " and the upper vehicle velocity threshold value "v_o ".

5. Apparatus according to claim 1, including;

means for providing a yet lower vehicle velocity threshold value "v_ua ";

said yet lower vehicle velocity threshold value "v_ua " is smaller than the vehicle velocity threshold value "v_u ";

means for actuating the actuators when the value of the vehicle velocity "v_o " has dropped below said yet lower vehicle velocity threshold value "v_v " and the instantaneous vehicle velocity signal "v" is below the lower vehicle velocity threshold value "v_u ".

6. A suspension system comprising means for the recognition of cornering for a vehicle with an active hydraulic system;

said means for the recognition of cornering for a vehicle with an active hydraulic system comprising a supply pump for the hydraulic system, a plurality of actuators, a number of valves for control of the actuators and a measuring device for determination of vehicle movement parameters,

said means for the recognition of cornering for a vehicle with an active hydraulic system further comprising;

means for measuring a vehicle acceleration signal "a";

means for providing an acceleration threshold value "a_s ";

means for comparing said vehicle acceleration signal "a" to said acceleration threshold value "a_s ";

means for measuring a vehicle velocity signal "v";

means for providing a lower vehicle velocity threshold value "v_u ";

means for comparing said vehicle velocity signal "v" to a lower vehicle velocity threshold value "v_u ";

means for providing an upper vehicle velocity threshold value "v_o "

means for comparing said vehicle velocity signal "v" to said upper vehicle velocity threshold value "v_o ";

means for providing a steering angle threshold value "s_delta ";

means for detecting a steering movement as a steering angle;

said means for detecting a steering movement as a steering angle comprising means for detecting said steering angle below and above said steering angle threshold value "s_delta ";

means for actuating power to the suspension system;

said means for detecting a steering movement as a steering angle comprising means for detecting said steering angle below and above said steering angle threshold value "s_delta ";

means for actuating power to the suspension system;

said means for actuating power to the suspension system comprising means for providing a signal to said valves for control of the actuators;

said means for providing a signal to said valves for control of the actuators comprising means for providing a signal to said valves at a vehicle velocity in the vehicle velocity range between the vehicle velocity threshold values "v_u " and "v_o ";

said means for providing a signal to said valves at a vehicle velocity in the vehicle velocity range between the vehicle velocity threshold values "v_u " and "v_o " comprising means for providing a signal to said valves only if the actual measured acceleration "a" increases above the acceleration threshold value "a_s " at the same time as the vehicle velocity is in the vehicle velocity range between the vehicle velocity threshold values "v_u " and "v_o ";

a spring for applying a substantially longitudinally directed force with said shock absorber;

said spring being operatively connected to apply the force to said shock absorber.

7. The suspension system according to claim 6, wherein:

said means for the recognition of cornering comprises;

means for comparing said vehicle velocity signal "v" to said upper vehicle velocity threshold "v_o ";

said means for comparing said vehicle velocity signal "v" to said upper vehicle velocity threshold "v_o " comprises means for determining when said vehicle velocity signal "v" is greater than "v_o ";

means for determining a steering angle of the vehicle;

means for providing a signal for actuating power to the suspension system relating to the vehicle acceleration signal "a" without consideration of the steering angle threshold value "s_delta ".

8. The suspension system according to claim 7 wherein:

means for providing a yet lower vehicle acceleration threshold value "a_h ";

said yet lower vehicle acceleration threshold value a_h being an acceleration less than said vehicle acceleration value "a_s ";

means for deactivating the actuators;

said means for deactivating the actuators comprising;

means for sensing the previous vehicle speed signal "v" being above "v_o " and for sensing the actual value of vehicle acceleration being below the yet lower vehicle acceleration threshold value "a_h "; and

means for deactivating the actuators upon said sensing means sensing the previous vehicle speed signal "v" as being above "v_o " and the actual value of vehicle acceleration as being below the yet lower vehicle acceleration threshold value "a_h ".

9. The suspension system according to claim 6 including:

means for providing a yet lower vehicle acceleration threshold value "a_h ";

said yet lower vehicle acceleration threshold value "a_h " being smaller than the vehicle acceleration threshold value "a_s ";

means for determining when the acceleration "a⃡

is below the yet lower vehicle acceleration threshold value "a_h " and the steering angle is below the steering angle threshold value "s_delta ";

means for actuating the actuators upon said determining means determining that the acceleration "a" is below the yet lower vehicle acceleration threshold value "a_h " and the steering angle is below the steering angle threshold value "s_delta ";

said means for determining indicating a signal that both the steering angle is below the steering angle threshold value and the vehicle acceleration value is below the yet lower vehicle acceleration threshold value "a_h " upon the instantaneous vehicle velocity signal "v" being below the lower vehicle velocity threshold value "v_u " and the upper vehicle velocity threshold value "v_o ".

10. The suspension system according to claim 6, including:

means for providing a yet lower vehicle velocity threshold value "v_ua ";

said yet lower vehicle velocity threshold value "v_ua " is smaller than the vehicle velocity threshold value "v_u ";

means for actuating the actuators when the value of the vehicle velocity "v_o " has dropped below said yet lower vehicle velocity threshold value "v_u " and the instantaneous vehicle velocity signal "v" is below the lower vehicle velocity threshold value "v_u ".

11. Method of operating an active suspension system in a vehicle with an active hydraulic system comprising a supply pump for the hydraulic system, a plurality of actuators, a number of valves for control of the actuators and a measuring device for determination of vehicle movement parameters, said method comprising:

providing an acceleration threshold value "a_s ";

providing a lower vehicle velocity threshold value "v_u ";

providing an upper vehicle velocity threshold value "v_o ";

providing a steering angle threshold value "s_delta ";

measuring a vehicle acceleration signal "a";

comparing said vehicle acceleration signal "a" to said acceleration threshold value "a_s ";

measuring a vehicle velocity signal "v";

comparing said vehicle velocity signal "v" to a lower vehicle velocity threshold value "v_u ";

comparing said vehicle velocity signal "v" to said upper vehicle velocity threshold value "v_o ";

detecting a steering movement as a steering angle below and above said steering angle threshold value "s_delta ";

actuating power to the suspension system, by a signal to said valves for control of the actuators, at a vehicle velocity in the vehicle velocity range between the vehicle velocity threshold values "v_u " and "v_o ", and actuating the actuators only if actual measured acceleration "a" simultaneously increases above the acceleration threshold value "a_s ".

12. Method according to claim 11, including:

recognizing cornering by said means for the recognition of cornering comprising;

comparing, by means for comparing, said vehicle velocity signal "v" to said upper vehicle velocity threshold "v_o ";

said means for comparing said vehicle velocity signal "v" to said upper vehicle velocity threshold "v_o " comprises means for determining when said vehicle velocity signal "v" is greater than "v_o ";

determining, by means for determining, a steering angle of the vehicle;

providing a signal, by means for providing a signal, for actuating power to the suspension system relating to the vehicle acceleration signal "a" without consideration of the steering angle threshold value "s_delta ".

13. Method according to claim 12 wherein:

providing, by means for providing, a yet lower vehicle acceleration threshold value "a_h ";

said yet lower vehicle acceleration threshold value a_h being an acceleration less than said vehicle acceleration value "a_s ";

deactivating the actuators, by means for deactivating the actuators;

said deactivating the actuators comprising;

sensing, by means for sensing, the previous vehicle speed signal "v" being above "v_o " and sensing, by means for sensing, the actual value of vehicle acceleration being below the yet lower vehicle acceleration threshold value "a_h "; and

deactivating the actuators, by means for deactivating the actuators, upon said sensing means sensing the previous vehicle speed signal "v" as being above "v_o " and the actual value of vehicle acceleration as being below the yet lower vehicle acceleration threshold value "a_h ".

14. Method according to claim 11 including:

providing, by means for providing, a yet lower vehicle acceleration threshold value "a_h ";

said yet lower vehicle acceleration threshold value "a_h " being smaller than the vehicle acceleration threshold value "a_s ;

determining, by means for determining, when the acceleration "a" is below the yet lower vehicle acceleration threshold value "a_h " and the steering angle is below the steering angle threshold value "s_delta ";

actuating the actuators, by means for actuating the actuators upon said determining means determining that the acceleration "a" is below the yet lower vehicle acceleration threshold value "a_h " and the steering angle is below the steering angle threshold value "s_delta ";

indicating a signal, by said means for determining, that both the steering angle is below the steering angle threshold value and the vehicle acceleration value is below the yet lower vehicle acceleration threshold value "a_h " upon the instantaneous vehicle velocity signal "v" being below the lower vehicle velocity threshold value "v_u " and the upper vehicle velocity threshold value "v_o ".

15. Method according to claim 11, including:

providing, by means for providing a yet lower vehicle velocity threshold value "v_ua ";

said yet lower vehicle velocity threshold value "v_ua " is smaller than the vehicle velocity threshold value "v_u ";

actuating the actuators, by means for actuating the actuators, when the value of the vehicle velocity "v_o " has dropped below said yet lower vehicle velocity threshold value "v_u " and the instantaneous vehicle velocity signal "v" is below the lower vehicle velocity threshold value "v_u ".