Vehicle suspension apparatus

• US 4,856,813 A
• Filed: 10/11/1988
• Issued: 08/15/1989
• Est. Priority Date: 10/15/1987
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation), Mitsubishi Jidosha Kogyo Kabushiki Kaisha
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation), Mitsubishi Jidosha Kogyo Kabushiki Kaisha
• Inventors: Tanaka, Tadao, Terada, Tetsuya, Ohtagaki, Shigeki, Wada, Shunichi, Harara, Mitsuhiko, Taniguchi, Yasutaka, Tatemoto, Minoru, Takizawa, Shozo, Mitsuhata, Kouji
• Primary Examiner(s): Rice, Kenneth R.
• Application Number:
  US07/255,778
• Time in Patent Office: 308 Days
• Field of Search: 280/703, 280/707, 280/840, 280/6.12, 280/DIG. 1
• US Class Current: 280/5.513
• CPC Class Codes: B60G 17/0164 mainly during accelerating or braking
• 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 2400/204 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 2400/50 Pressure
• CPC Class Codes: B60G 2600/02 Retarders, delaying means, dead zones, threshold values, cut-off frequency, timer interruption
• CPC Class Codes: B60G 2600/26 Electromagnets; Solenoids
• CPC Class Codes: B60G 2600/66 Humidifying or drying means
• 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 2800/24 Steering, cornering

Abstract

If a deceleration exeeds first set value G1 within set time T1 after the brake is depressed, a set amount of fluid is supplied to the fluid spring chamber of each front-wheel suspension unit. If a deceleration exceeds the second set value G2 when set time T1 or more has elapsed upon this operation, a set amount of fluid is exhausted from the fluid spring chamber of each rearwheel suspension unit. With this operation, since braking action for gradually increasing a deceleration is controlled by two stages, uncomfortableness which passangers feel in anti-nose-dive control can be greatly reduced. In addition, control is not performed only by depressing the brake pedal if an acutal deceleration is smaller than first set value G1. Even when a deceleration exceeds first set value G1 upon depression of the brake pedal, if the time when the deceleration exceeds first set value G1 exceeds set time T1, it is determined that a gradual braking operation is performed, so that only control for increasing a damping force is performed.

Claims

1. A vehicle suspension apparatus, comprising:

front and rear suspensions, each having a fluid spring chamber, for supporting front and rear wheels;

fluid supply means for supplying a fluid to said fluid spring chambers through front- and rear-wheel supply valves;

fluid exhaust means for exhausting the fluid from said fluid spring chambers through front- and rear-wheel exhaust valves;

brake operation detecting means for detecting an operation state of brake operating means;

deceleration detecting means for detecting a deceleration of a vehicle;

fluid spring chamber control means for outputting a first control signal for opening said front-wheel supply valves for a set control time when said brake operation detecting means and said deceleration detecting means detects that said brake operating means is operated and a deceleration exceeds a first set value within a first set time from a timing at which said brake operating means is started,

outputting a second control signal for opening said rear-wheel exhaust valves for a set control time when said brake operation detecting means and said deceleration detecting means then detect that while said brake operating means is operated, the deceleration of said vehicle exceeds a second set value which is larger than the first set value, and

outputting a third control signal to said front wheel exhaust valves and rear-wheel supply valves so as to return a fluid amount in each of said fluid spring chambers to a value prior to a control operation when said brake operation detecting means detect after the above operation that the brake operating means is set in an inoperative state, or when the deceleration detecting means detect after the above operation that the deceleration of said vehicle becomes smaller than a third set value which is not more than the first set value.

2. An apparatus according to claim 1, further comprising:

a damping force variable type shock absorber arranged in each of said front and rear suspensions;

target damping force setting means for setting a target damping force in accordance with a control target obtained by said deceleration detecting means; and

shock absorber control means for changing the damping force of said shock absorber in accordance with the target damping force set by said target damping force setting means.

3. An apparatus according to claim 2, wherein said shock absorber control means increases the damping force of said shock absorber when said fluid spring chamber control means outputs the first or second control signal, and changes the damping force to a state prior to the control operation when said fluid spring chamber control means outputs the third control signal.

4. An apparatus according to claim 1, wherein said vehicle velocity detecting means comprises a vehicle velocity sensor and calculates the deceleration of said vehicle on the basis of a vehicle velocity detected by said vehicle velocity sensor.

5. An apparatus according to claim 1, wherein said deceleration detecting means detects the deceleration of said vehicle by using a sensor for detecting a decelerated state of said vehicle.