Automotive active suspension system for regulating vehicular height level during anti-rolling control

• US 5,396,423 A
• Filed: 01/21/1992
• Issued: 03/07/1995
• Est. Priority Date: 01/22/1991
• Status: Expired due to Fees

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Fukuyama, Kensuke, Akatsu, Yohsuke, Fujimura, Itaru, Fukushima, Naoto, Sato, Masaharu
• Primary Examiner(s): DEWITT, LAVONDA R
• Assistant Examiner(s): Park, Collin W.
• Application Number:
  US07/882,274
• Time in Patent Office: 1,141 Days
• Field of Search: 364/424.05, 280/840, 280/6.1, 280/6.12, 280/707, 280/DIG. 1
• 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 2400/104 lateral or transversal with regard to vehicle
• CPC Class Codes: B60G 2400/1042 using at least two sensors
• CPC Class Codes: B60G 2400/51 in suspension unit
• CPC Class Codes: B60G 2400/61 Load distribution
• CPC Class Codes: B60G 2400/63 Location of the center of gravity
• CPC Class Codes: B60G 2500/20 Spring action or springs
• CPC Class Codes: B60G 2800/24 Steering, cornering

Abstract

An active suspension system is provided which includes hydraulic cylinders for suppressing rolling motion of a vehicle body. The system is responsive to lateral acceleration acting on the vehicle body to provide a control signal for supplying hydraulic pressure to the cylinders for anti-rolling control. The control signal includes first and second pressure control signals. The first pressure control signal commands supply of hydraulic pressure for providing an anti-rolling moment, while the second pressure control signal commands supply of hydraulic pressure for supporting a portion of the static load of the vehicle body to maintain the vehicle body at a target height level. The system is further responsive to increase in lateral acceleration to modify the second pressure control signal to reduce the hydraulic pressure for supporting the portion of static load, thereby compensating for forces acting to raise the vehicle body caused by the anti-rolling control for establishing a constant vehicular height level irrespective of variation in the lateral acceleration acting on the vehicle body.

Claims

1. A method for actively controlling vehicular active suspension units, said active suspension units being disposed between a vehicle body and respective front left, front right, rear left, and rear right tire wheels, comprising steps of:

a) monitoring a magnitude and direction of a lateral acceleration acted upon a vehicle body;

b) providing neutral pressure command values VN_F and VN_R having voltages varied according to the monitored magnitude and direction of the lateral acceleration, said neutral pressure command values being decreased as the magnitude of the lateral acceleration is increased;

c) providing gain adjusted values VL_F and VL_R of anti-rolling command values according to the magnitude and direction of the lateral acceleration, said gains K_F and a rear tire wheel side anti-roll control gain K_R and said anti-rolling command values being multiplication of both the corresponding anti-roll gain and magnitude and direction of the lateral acceleration;

d) adding the neutral pressure command values VN_F and VN_R to anti-rolling command values VL_F and VL_R to provide the added values to driving circuits for front left and rear left suspension units, respectively, and adding the neutral pressure command values VN_F and VN_R to inverted values of anti-rolling command values VL_F and VL_R to provide the added values to driving circuits for front right and rear right suspension units, respectively; and

e) converting the added values into respective energizing currents i_FL, i_FR, i_RL, and i_RR, respectively, to be input to respective pressure control valves of the front left, front right, rear left and rear right suspension units so that the anti-roll and jacking up suppression controls are carried out for the respective suspension units.

2. A method for actively controlling vehicular suspension units as set forth in claim 1, wherein a total gain of both anti-roll gains (K=K_F +K_R) is set such that a rolling motion generated when the lateral acceleration acted upon the vehicle body gives approximately zero.

3. A method for actively controlling vehicular suspension units as set forth in claim 2, wherein K_F >

K_R.

4. A method for actively controlling vehicular suspension units as set forth in claim 3, wherein each of the neutral command values VN_F and VN_R are such that a positive predetermined value VN₀ to receive a burden of a part of a static weight of the vehicle body is given thereto when the monitored lateral acceleration indicates approximately zero and a gradually decreased value VN_F or VN_R is given when the monitored lateral acceleration G is increased in the direction of either plus or minus.

5. A method for actively controlling vehicular suspension units as set forth in claim 4, wherein a rate of decrease in the one neutral command value VN_F is smaller than that in the other neutral command value VN_R.

6. A method for actively controlling vehicular suspension units as set forth in claim 5, wherein each of said pressure control valves comprises a proportional solenoid valve.

7. A method for actively controlling vehicular suspension units as set forth in claim 1, wherein said step a) monitors the lateral accelerations acted upon vehicular front and rear axles of the vehicle body.

8. A method for actively controlling vehicular suspension units as set forth in claim 7, wherein said step a) further comprises a step f) calculating one lateral acceleration G_F acted upon the vehicular front axle and g) calculating another lateral acceleration G_R acted upon the vehicular rear axle, the magnitude and direction of the one lateral acceleration G_F being provided for the neutral command values VN_F for the front suspension units and those of the other lateral acceleration G_R being provided for the neutral command values VN_R.