Method of controlling active suspensions for an automotive vehicle

• US 5,029,328 A
• Filed: 10/24/1989
• Issued: 07/02/1991
• Est. Priority Date: 10/31/1988
• Status: Expired due to Term

• Current Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Original Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Inventors: Hiwatashi, Yutaka, Mine, Atsushi, Kamimura, Katsuyoshi
• Primary Examiner(s): Chin, Gary
• Application Number:
  US07/425,961
• Time in Patent Office: 616 Days
• Field of Search: 364/424.05, 280/707, 280/840
• US Class Current: 701/38
• 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 2202/15 Fluid spring
• CPC Class Codes: B60G 2204/80 Interactive suspensions; arrangement affecting more than one suspension unit
• CPC Class Codes: B60G 2400/10 Acceleration; Deceleration
• CPC Class Codes: B60G 2400/102 vertical
• CPC Class Codes: B60G 2400/104 lateral or transversal with regard to vehicle
• CPC Class Codes: B60G 2400/106 longitudinal with regard to vehicle, e.g. braking
• CPC Class Codes: B60G 2400/206 Body oscillation speed; Body vibration frequency
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2400/60 Load
• CPC Class Codes: B60G 2400/63 Location of the center of gravity
• CPC Class Codes: B60G 2400/91 Frequency
• CPC Class Codes: B60G 2500/10 Damping action or damper
• CPC Class Codes: B60G 2500/20 Spring action or springs
• CPC Class Codes: B60G 2500/30 Height or ground clearance
• CPC Class Codes: B60G 2600/02 Retarders, delaying means, dead zones, threshold values, cut-off frequency, timer interruption
• CPC Class Codes: B60G 2600/14 Differentiating means, i.e. differential control
• CPC Class Codes: B60G 2600/20 Manual control or setting means
• CPC Class Codes: B60G 2600/604 low pass
• CPC Class Codes: B60G 2800/012 Rolling condition
• CPC Class Codes: B60G 2800/014 : Pitch; Nose dive
• CPC Class Codes: B60G 2800/24 : Steering, cornering

Abstract

To carry out a method of controlling a plurality of active suspensions for an automotive vehicle, a normal/reverse rolling selection switch and a plurality of correction logics are provided in a control system including a longitudinal acceleration sensor and a lateral acceleration sensor. The correction logics correct a quantity of rolling moment, a variation of suspension reactive force, a control quantity of fluid and variation of a reference vehicle height. A signal from the lateral acceleration sensor and a signal from the normal/reverse rolling selection switch are inputted into a reference vehicle height correcting circuit to control a reference vehicle height corresponding to each active suspension.

Claims

1. A method of controlling a plurality of active suspensions for an automotive vehicle, each of said active suspensions having respective valves to feed fluid in the active suspension and discharge said fluid from the active suspension, wherein said method comprises the steps of;

detecting a lateral acceleration,

indicating a desired rolling angle and a rolling direction in dependency on a selection of a normal/reverse rolling selection switch,

calculating a rolling moment in response to said lateral acceleration and said desired rolling angle,

computing a lateral displacement quantity for each wheel in response to said rolling moment,

deriving a variation of a lateral force for each wheel in response to the lateral acceleration,

estimating a vertical variation of a vertical reactive force for each wheel in consideration of deformation of the active suspension in response to the lateral displacement quantity, the lateral force, type of the active suspension links and the desired rolling angle,

deciding a first control quantity corresponding to the amount of fluid to feed in or discharge from the active suspension in response to the estimated vertical variation of the vertical reactive force, and

operating a control valve for each said active suspension in response to the first control quantity so as to maintain an optimum rolling angle.

2. The method as claimed in claim 1 further comprising the steps of;

detecting a vertical relative displacement,

generating a reference vehicle height in response to a signal of a vehicle height adjusting switch,

calculating a difference between the vertical relative displacement and the reference vehicle height,

computing an actual rolling angle in response to the lateral acceleration,

deriving a desired vertical relative displacement corresponding to the actual rolling angle,

correcting the difference from the desired vertical relative displacement, and

estimating a second control quantity to reduce the corrected difference equal to zero so as to operate the control valve in response to the first and second control quantities.