Automotive vehicle suspension control system

• US 5,935,181 A
• Filed: 07/01/1996
• Issued: 08/10/1999
• Est. Priority Date: 07/04/1995
• Status: Expired due to Fees

• Current Assignee: Unisia Jecs Corporation (Hitachi, Ltd.)
• Original Assignee: Unisia Jecs Corporation (Hitachi, Ltd.)
• Inventors: Iwasaki, Katsuya
• Primary Examiner(s): LOUIS JACQUES, JACQUES H
• Application Number:
  US08/674,165
• Time in Patent Office: 1,135 Days
• Field of Search: 701/36, 701/37, 701/38, 701/48, 701/70, 280/707, 280/840, 280/703, 280/708, 280/702, 280/5.51, 280/5.515, 280/5.512, 280/5.507, 280/6.159, 180/41, 180/312, 180/902
• US Class Current: 701/37
• CPC Class Codes: B60G 17/0164 mainly during accelerating or braking
• CPC Class Codes: B60G 17/018 characterised by the use of a specific signal treatment or control method
• CPC Class Codes: B60G 17/08 Characteristics of fluid dampers adjusting fluid dampers in general F16F9/44 - F16F9/53
• CPC Class Codes: B60G 2202/24 Fluid damper
• CPC Class Codes: B60G 2400/102 vertical
• CPC Class Codes: B60G 2400/106 longitudinal with regard to vehicle, e.g. braking
• CPC Class Codes: B60G 2400/202 Piston speed; Relative velocity between vehicle body and wheel
• CPC Class Codes: B60G 2400/204 Vehicle speed
• CPC Class Codes: B60G 2400/206 Body oscillation speed; Body vibration frequency
• CPC Class Codes: B60G 2400/91 Frequency
• CPC Class Codes: B60G 2500/11 Damping valves
• CPC Class Codes: B60G 2600/02 Retarders, delaying means, dead zones, threshold values, cut-off frequency, timer interruption
• CPC Class Codes: B60G 2800/014 Pitch; Nose dive
• CPC Class Codes: B60G 2800/18 Starting, accelerating
• CPC Class Codes: B60G 2800/22 Braking, stopping
• CPC Class Codes: B60G 2800/916 Body Vibration Control
• CPC Class Codes: F16F 9/468 controlling at least one bypass to main flow path

Abstract

A suspension control system for use with shock absorbers provided between sprung and unsprung masses of an automotive vehicle at the positions of the respective vehicle road wheels for providing variable damping force characteristics. The suspension control system includes sensors mounted on the vehicle for sensing sprung mass vertical accelerations acting in a predetermined direction with respect to the vehicle at the respective road wheel positions. A component of the vehicle longitudinal acceleration acting in the predetermined direction is calculated as a function of vehicle pitching angle and vehicle longitudinal acceleration. The sensed sprung mass vertical accelerations are corrected in a direction to cancel the calculated vehicle longitudinal acceleration component. The shock absorbers are controlled based on the respective corrected sprung mass vertical accelerations.

Claims

1. A suspension control system for use with an automotive vehicle supported on front-left and -right road wheels at front-left and -right road wheel positions and also on rear-left and -right road wheels at rear-left and -right road wheel positions, comprising:

shock absorbers provided between sprung and unsprung masses of the vehicle at the respective road wheel positions for providing variable damping force characteristics;

sensors mounted on the vehicle for sensing sprung mass vertical accelerations acting in a predetermined direction with respect to the vehicle at the respective road wheel positions; and

a control unit for determining a vehicle longitudinal acceleration, the control unit calculating a vehicle pitching angle based on the determined vehicle longitudinal acceleration, the control unit calculating a component of the vehicle longitudinal acceleration acting in the predetermined direction based on the calculated vehicle pitching angle and the determined vehicle longitudinal acceleration, the control unit correcting the sensed sprung mass vertical accelerations to cancel the calculated vehicle longitudinal acceleration component, and the control unit controlling the shock absorbers based on the respective corrected sprung mass vertical accelerations.

2. The suspension control system as claimed in claim 1, wherein the control unit includes a vehicle longitudinal acceleration sensor for sensing the longitudinal acceleration of the sprung mass.

3. The suspension control system as claimed in claim 1, wherein the control unit includes a vehicle speed sensor for sensing a speed of running of the vehicle, the control unit determining the vehicle longitudinal acceleration based on the sensed vehicle running speed.

4. The suspension control system as claimed in claim 1, wherein the control unit includes a road wheel speed sensor for sensing a speed of rotation of one of the road wheels, the control unit determining the vehicle longitudinal acceleration based on the sensed road wheel speed.

5. A suspension control system for use with an automotive vehicle supported on front-left and -right road wheels at front-left and -right road wheel positions and also on rear-left and -right road wheels at rear-left and -right road wheel positions, comprising:

first and second sensors configured to respectively sense a sprung mass vertical acceleration at front-left and front-right positions of the automotive vehicle, and to respectively output first and second sensed signals as a result;

a first unit configured to receive the first and second sensed signals from the first and second sensors, respectively, to calculate a bounce rate at a center position between the front-left and -right road wheel positions, and to output a first output signal in accordance with the calculated bounce rate;

a second unit configured to receive the first output signal from the first unit, to calculate a filtered bounce rate at the center position based on the first output signal, a first transfer function that is based on a first road surface input from the front-left and -right road wheel positions, a second transfer function that is based on a second road surface input from the rear-left and -right road wheel positions, and a third transfer function that is based on difference between input times of the first and second road surface inputs, and to output a second output signal as a result;

a third unit configured to receive the first and second sensed signals from the first and second sensors, respectively, and to calculate a vehicle roll rate at a front wheel side, and to output a third output signal in accordance with the calculated bounce rate;

a fourth unit configured to receive the third output signal from the third unit and to apply a fourth transfer function to the third output signal so as to calculate and output a fourth output signal;

a fifth unit configured to receive the second output signal and the fourth output signal, and to calculate and output, as a fifth output signal, a sprung mass vertical acceleration at the rear-right road wheel position;

a sixth unit configured to receive the second output signal and the fourth output signal, and to calculate and output, as a sixth output signal, a sprung mass vertical acceleration at the rear-left road wheel position;

a seventh unit configured to receive the first sensed signal and to apply a fifth transfer function to the first sensed signal so as to calculate and output, as a seventh output signal, a high frequency component of the first sense d signal that is transmitted to the rear-left and -right road wheel positions;

an eighth unit configured to receive the second sensed signal and to apply a sixth transfer function to the first sensed signal so as to calculate and output, as an eighth output signal, a high frequency component of the second sensed signal that is transmitted to the rear-left and -right road wheel positions;

a ninth unit configured to receive the fifth output signal and the seventh output signal, and to calculate a rear-right sprung mass vertical acceleration as a result; and

a tenth unit configured to receive the sixth output signal and the eighth output signal, and to calculate a rear-left sprung mass vertical acceleration as a result.