Suspension control apparatus for a vehicle

• US 4,887,840 A
• Filed: 11/07/1988
• Issued: 12/19/1989
• Est. Priority Date: 11/05/1987
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Kenki Kabushiki Kaisha
• Inventors: Tanaka, Tadao, Ohtagaki, Shigeki, Wada, Shunichi, Harara, Mitsuhiko, Takizawa, Shozo
• Primary Examiner(s): Bertsch, Richard A.
• Application Number:
  US07/267,951
• Time in Patent Office: 407 Days
• Field of Search: 180/41, 280/707, 280/640, 280/6.1, 280/6.11, 280/703, 280/709, 280/DIG. 1
• US Class Current: 280/5.503
• 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 2202/15 Fluid spring
• CPC Class Codes: B60G 2204/11 Mounting of sensors thereon
• CPC Class Codes: B60G 2204/422 Links for mounting suspension elements
• CPC Class Codes: B60G 2204/81 front and rear unit
• 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 2400/252 vertical
• CPC Class Codes: B60G 2400/34 Accelerator pedal position
• CPC Class Codes: B60G 2400/44 Steering speed
• CPC Class Codes: B60G 2400/821 Uneven, rough road sensing affecting vehicle body vibration
• CPC Class Codes: B60G 2401/00 Indexing codes relating to the type of sensors based on the principle of their operation
• CPC Class Codes: B60G 2401/14 Photo or light sensitive means, e.g. Infrared
• CPC Class Codes: B60G 2401/17 Magnetic/Electromagnetic
• CPC Class Codes: B60G 2500/10 Damping action or damper
• 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 2600/12 Sampling or average detecting; Addition or substraction
• CPC Class Codes: B60G 2600/14 Differentiating means, i.e. differential control
• CPC Class Codes: B60G 2600/26 Electromagnets; Solenoids
• CPC Class Codes: B60G 2600/66 : Humidifying or drying means
• CPC Class Codes: B60G 2600/68 : Filtering means, e.g. fluid filters
• CPC Class Codes: B60G 2600/70 : Computer memory; Data storage, e.g. maps for adaptive control
• CPC Class Codes: B60G 2800/012 : Rolling condition
• CPC Class Codes: B60G 2800/014 : Pitch; Nose dive
• CPC Class Codes: B60G 2800/019 : Inclination due to load distribution or road gradient
• CPC Class Codes: B60G 2800/162 : Reducing road induced vibrations
• CPC Class Codes: B60G 2800/20 : Stationary vehicle
• CPC Class Codes: B60G 2800/24 : Steering, cornering

Abstract

Disclosed is a suspension control apparatus for a vehicle having a plurality of suspension units each disposed between a road wheel and the body of a vehicle for effectively and quickly correcting any deviation of the vehicle height from a normal height level immediately upon finishing of active suspension control operations. Priority is determined for vehicle-height control and various active suspension control operations such as roll control, nose-dive and squat control, and pitching and bouncing control so that normal vehicle-height control is stopped or inhibited during active suspension control operations are being carried out, thereby preventing the traveling attitude of the vehicle from being made unstable. Also, a vehicle-height control determining time interval from the instant when active suspension control operations has been finished until the time when vehicle-height control is restarted is substantially reduced as compared with that required in the case when the vehicle is traveling in a normal attitude without any active suspension control operation, whereby any deviation of the vehicle height from a target height level can be quickly removed to make the actual vehicle height match with a target height level in a very short time immediately after the finishing of the active suspension control operations.

Claims

1. A suspension control apparatus for a vehicle comprising:

a plurality of suspension units each disposed between a road wheel and the body of a vehicle for suspending the corresponding road wheel from the vehicle body;

a vehicle-height sensing means sensing a vertical distance between an axle of each of said road wheels and a specific portion of the vehicle body;

roll sensing means sensing a rolling state of the vehicle body;

nose-dive and squat sensing means sensing a nose-dive state and a squat state of the vehicle;

pitching and bouncing sensing means sensing vertical movements of the vehicle body including pitching and bouncing thereof; and

a control unit electrically connected to receive outputs of said vehicle-height sensing means, said roll sensing means, said nose-dive and squat sensing means, and said pitching and bouncing sensing means for controlling said suspension units in such a manner that if there is a difference between the vertical distance sensed by said vehicle-height sensing means and the target vehicle height, the difference is reduced to zero, and that forces acting between the road wheels and the vehicle body are adjusted to suppress the nose diving, squatting, pitching and bouncing of the vehicle body, said control unit being further operable to determine the order of priority for the vehicle-height and roll control, the nose-dive and squat control, and the pitching and bouncing control so that the vehicle-height control is stopped during the time when a control having higher priority than the vehicle-height control is being carried out.

2. A suspension control apparatus for a vehicle as claimed in claim 1, wherein said control unit is further operable to reduce a height-control determining time interval between the finishing of the height-control stopping operation and the starting of the vehicle-height controlling operation in comparison with that required during a normal operating state of the vehicle in which no active suspension control is performed.

3. A suspension control apparatus for a vehicle as claimed in claim 1, wherein said control unit comprises:

vehicle-height controlling means for comparing the vertical distance sensed by said vehicle-height sensing means with a target vehicle height and for controlling the operations of said suspension units in such a manner that if there is a difference between the vertical distance sensed by said vehicle-height sensing means and the target vehicle height, said suspension units are operated to reduce the difference to zero;

first memory means for storing a roll controlling quantity corresponding to the rolling state of the vehicle body sensed by said roll sensing means;

roll controlling means for controlling the operations of said suspension units in accordance with the roll controlling quantity stored in said first memory means so as to suppress the rolling of the vehicle body;

second memory means storing a nose-dive controlling quantity and a squat controlling quantity corresponding to the nose-dive state and the squat state, respectively, of the vehicle body sensed by said nose-dive and squat sensing means;

nose-dive and squat controlling means for controlling the operations of said suspension units in accordance with the nose-dive and squat controlling quantities stored in said second memory means so as to suppress the nose diving and squatting of the vehicle body;

third memory means storing a pitching controlling quantity and a bouncing controlling quantity corresponding to the pitching and the bouncing of the vehicle body sensed by said pitching and bouncing sensing means;

pitching and bouncing controlling means for controlling the operations of said suspension units in accordance with the pitching and bouncing controlling quantities stored in said third memory means so as to suppress the pitching and bouncing of the vehicle body;

priority determining means for determining the order of priority for the vehicle-height and roll control, the nose-dive and squat control, and the pitching and bouncing control; and

height-control stopping means for stopping vehicle-height control during the time when a control having higher priority than the vehicle-height control as determined by said priority determining means is being carried out.

4. A suspension control apparatus for a vehicle as claimed in claimed in claim 3, wherein said control unit further comprises time-saving means for reducing a height-control determining time interval between the finishing of the height-control stopping operation of said height-control stopping means and the starting of the vehicle-height controlling operation in comparison with that required during a normal operating state of the vehicle in which no active suspension control is performed.