Apparatus and method for controlling damping force characteristic of vehicular suspension system

• US 5,832,398 A
• Filed: 10/09/1997
• Issued: 11/03/1998
• Est. Priority Date: 10/12/1994
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Unisia Jecs Corporation (Hitachi, Ltd.)
• Inventors: Sasaki, Mitsuo, Iwasaki, Katsuya
• Primary Examiner(s): Chin, Gary
• Application Number:
  US08/947,854
• Time in Patent Office: 390 Days
• Field of Search: 701/37, 701/38, 701/39, 280/707, 280/840
• US Class Current: 701/37
• CPC Class Codes: B60G 17/0152 characterised by the action on a particular type of suspension unit B60G17/01941 takes precedence
• CPC Class Codes: B60G 17/016 characterised by their responsiveness, when the vehicle is travelling, to specific motion, a specific condition, or driver input B60G17/017 takes precedence
• CPC Class Codes: B60G 17/08 Characteristics of fluid dampers adjusting fluid dampers in general F16F9/44 - F16F9/53
• CPC Class Codes: B60G 2206/41 Dampers
• CPC Class Codes: B60G 2400/102 vertical
• CPC Class Codes: B60G 2400/204 Vehicle speed
• CPC Class Codes: B60G 2400/206 Body oscillation speed; Body vibration frequency
• CPC Class Codes: B60G 2500/10 Damping action or damper
• CPC Class Codes: B60G 2500/11 Damping valves
• CPC Class Codes: B60G 2600/184 Semi-Active control means
• CPC Class Codes: B60G 2600/602 high pass
• CPC Class Codes: B60G 2600/604 low pass
• CPC Class Codes: B60G 2800/70 Estimating or calculating vehicle parameters or state variables
• CPC Class Codes: F16F 9/468 controlling at least one bypass to main flow path

Abstract

In apparatus and method for controlling a damping force characteristic of each of front and rear left and right road wheel positioned shock absorbers based on a Sky Hook control theory, rear left and right road wheel position vehicular behaviors are estimated using a predetermined transfer function established between front road wheel position vehicular behaviors and rear road wheel position vehicular behaviors from front left and right road wheel position vehicular behavior related signals with the damping force characteristics of the rear road wheel positioned shock absorbers controlled on the basis of rear road wheel position control signals formed for the rear left and right road wheel positioned shock absorbers on the basis of the estimated rear road wheel position vehicular behaviors.

Claims

1. A method for forming a control signal, said control signal being formed and outputted to damping force characteristic varying means for controlling a damping force characteristic of a shock absorber interposed between an unsprung mass and a sprung mass of a vehicle, said method comprising the steps of:

a) detecting a vertical acceleration acted on the sprung mass and outputting a signal indicative of the vertical acceleration of the sprung mass; and

b) converting the vertical acceleration indicative signal outputted at the step a) into a signal indicative of a vertical velocity of the sprung mass using a phase compensation filter (PCF), said control signal being formed on the basis of the converted sprung mass vertical velocity indicative signal.

2. A method for forming a control signal as claimed in claim 1, wherein said phase compensation filter has the following filter equation:

(0.001S+1)/(10S+1), wherein S denotes a complex variable and S=σ

+jω

, σ

denoting a real number, j denoting an imaginary number unit, and ω

denoting 2 π

f, f denoting a frequency.